Basic Engine and Compressor Analysis

8/9/2019 Basic Engine and Compressor Analysis

1/133

1

2003 DYNALCO CONTROLSGMRC 2003 GAS MACHINERY CONFERENCE

BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 1

Basic Reciprocating Engine &Compressor AnalysisTechniques

Azonix-DynalcoKathy Boutin, B.Sc.Ben Boutin, P.Eng.

2003 DYNALCO CONT ROLSGMRC 2003 GAS MACHINERY CONFERENCE

SHORT COURSE: BASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 2

Focus of this course

In this course, we illustrate engine andcompressor behavior using data taken fromrunning machinery

The data were recorded by analysts runningtheir own predictive maintenance programs

We show faults that are seen in recipequipment and present techniques to detect

them


2/133

2



Short Course Outline

Analysis Programs Characterizing engines and compressors

Data types Testpoint Locations

Sequence of events 2-stroke engines 4-stroke engines Compressors

Analyzing engine faults Analyzing compressor faults Analyzing auxiliary equipment faults



Analysis Programs

Objectives

Types of analysis Analysis process


3/133

3



Analysis ProgramsObjectives of analysis programs

Eliminate expensive, unnecessary maintenance Decrease maintenance costs Increase machine availability Decrease down time Improve performance Reduce emissions

You cant improve what you dont measure



Analysis Programs

Types of machinery analysis

Maintenance Analysis Identifies incipient failure so that you can turn unscheduledmaintenance into scheduled maintenance

Helps avoid in-service failures Goal is to reduce maintenance cost

Performance Analysis Characterizes the engine/compressor operating potential Efficiency

Fuel consumption Horsepower Throughput


4/133


5/133

5



Characterizing Engines and CompressorsSpecial data types

Process data Tell about the process Examples: suction temperature and pressure

Phase-marked data Data is referenced to the flywheel Example: pressure versus time data

Non-phased data Sampling is a function of time only Example: acceleration data from aturbocharger bearing



Characterizing Engines and Compressors

Measuring flywheel position

Once-per-degree Shaft encoder 360 pulses perrevolution

Better accuracy Once-per-turn

Magnetic, active oroptical pickups are

common 1 pulse per revolution Usually permanentlymounted


6/133

6



Characterizing Engines and CompressorsExample of phase-marked pressure (PT)

500

600

700

800

900

1000

1100

1200

1300

1400

1500

1600

1700

0 45 90 135 180 225 270 315 360

C402 - C cylinder 2 09/09/1998 12:02:53 PM HE Period 5, CE Period 5

P r e s s u r e ( p s i g )

Crank Angle (deg)

Head andcrank endpressuretraces on acompressorcylinder




Free-running, non-phased data

Data is recorded independent of crankshaft position Returns

Overall vibration level Spectrum showing frequency components

Common applications: Structural vibration Supports, foundations Turbochargers Oil and water pumps Pressure pulsation


7/133

7



Characterizing Engines and CompressorsExample of free-running, non-phased, spectrum data

Spectrum fromengine framenear anchorbolts. Mils peak-peak, oil pumpend, horizontaldirection.

Engine speed323 RPM

Testpoint : OPEH VIBNo. Of Lines : 400No. Of Averages : 5Calc Overall : N/ATrap Overall : 1.325

Peak At Frequency1.020 at 322.50.507 at 1305.00.122 at 652.50.110 at 487.50.098 at 1627.50.079 at 2932.50.073 at 1357.50.061 at 1140.00.061 at 1020.00.061 at 975.0

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

0 500 1000 1500 2000 2500 3000

UNIT #4-E Testpoint OPEH 7/17/2002 10:51:55 AM

m i l ( p s e u d o - p

k - p k )

cpm

1 timesrun speed

2 timesrun speed

4 timesrun speed

Engine Data

Cylinder exhaust temperatures Infrared temperature wand

pyrometer

Cylinder pressure Pressure transducer Time domain data phased to

crankshaft position Peak pressure statistics

Cylinder, valve, wrist pinand bearing vibration Ultrasonic microphone Standard accelerometer Time domain data phased to

crankshaft position

Frame vibration (displacement) Tri-axial accelerometer (H, V, A)

taken at opposite corners ofengine frame

Frequency domain data

Ignition secondary Inductive connection to unshielded

spark plug cable Multi-period sampling statistics Ignition secondary patterns

Ignition primary (not shown)

Connection to primary box Ignition primary firing patterns

Turbocharger/blower Standard accelerometer

mounted on bearings and nearturbine and compressor wheels

Frequency domain vibration

TDC Reference Shaft encoder Magnetic pickup Phased data RPM

2003 DYNALCO CONT ROLS


8/133

8



Characterizing Engines and CompressorsTypical 2-stroke engine PT/VT

223 Intake137242 Exhaust118

273Fuel 213

0

50

100

150

200

250

300

350

400

450

500

550

600

0 45 90 135 180 225 270 315 360

--------------

--------------

-

-

-

-

-

-

-

-

-

- Scale 2.4

P5 VT4

20905-E Cylinder P5 3/27/2002 8:57:46 AM Period 0


Angle (deg)

PT

VT




Typical 4-stroke engine PT/VT620Intake 281

391 Exhaust140583Fuel 315

0

100

200

300

400

500

600

700

800

900

1000

1100

0 45 90 135 180 225 270 315 360 405 450 495 540 585 630 675 720

--------------

--------------

-

-

-

-

-

-

-

-

-

- Scale 5.0

2L VT4

5302-E Cylinder 2L 12/3/2001 9:15:58 AM Period 1


Angle (deg)

PT

VT


9/133

9

TDC Reference Shaft encoder Magnetic pickup Phased data RPM

Suction/discharge temperatures Infrared temperature wand thermocouples, RTDs

Head/crank end pressure Pressure transducer Time domain data phased to

crankshaft position

Multi-period sampling statistics

Suction/discharge valve vibrationCompressor ring leak vibrationLiner scoring Ultrasonic microphone Standard accelerometer Time domain data phased to

crankshaft position

Frame vibration (displacement) Tri-axial accelerometer (H, V, A)

taken at opposite corners ofengine frame

Frequency domain data

Rod Motion Proximity probes Time-domain data phased to

crankshaft position Rod displacement trends

Suction/discharge nozzle pressure Pressure transducer Time domain data phased to crankshaft

position (valve/passage loss calculations) Frequency domain (pulsation spectrum) Multi-period sampling statistics

Valve cap temperatures Infrared temperature wand thermocouples, RTDs

Crosshead Vibration Standard accelerometer Time domain data phased to

crankshaft position

Relate to rod load

Compressor Data

2003 DYNALCO CONT ROLS




Typical HE compressor pattern

250

300

350

400

450

500

550

600

0 45 90 135 180 225 270 315 360

--------------

--------------

--------------

--------------

--------------

---------------------------------------

- Scale 3.084 DGF

- Scale 3.084 DGF

- Scale 3.0146 DGF

- Scale 3.0145 DGF

4HS2 VT1

4HS1 VT1

4HD2 VT1

4HD1 VT1

K200 - C cylinder 4 9/23/1998 9:52:15 AM HE Period 5, CE Period 7


Crank Angle (deg)

HE PT

HE VT

CE PT


10/133

10



Sequence of events

2-stroke, spark-ignited engine 4-stroke, spark-ignited engine Double-acting, reciprocating compressor



Understanding Machine Faults

To recognize faults in compressors andengines, we must understand how theybehave in normal operation

Do the mechanical events you expect to seeactually happen?

Do the events appear to be normal? when do they occur? what is the relative magnitude?

do they look the same as they did last time? do they look the same as the next machine?

What is the performance of the machine?


11/133

11



Sequence of eventsfor a 2 stroke engine

Pressure versus crank angle (PT) Pressure-Volume (PV) Vibration versus crank angle (VT)



Sequence of events for a 2-stroke engine

PT: start of cycle

180 270 360900

Crank Angle (Deg)

P r e s s u r e

Ignition has occurred

Flame front travel has begun

Mixture is superheated air and fuel


12/133


13/133

13



Sequence of events for a 2-stroke enginePT: exhaust blowdown

Piston uncovers exhaust port

Pressure drops more rapidly (blowdown)

Temperature is now about 800F

P r e s s u r e

00

90 180 270 360

Crank Angle (deg)




PT: air intake

Intake port is uncovered

Cylinder pressure intake pressure

Fresh air under pressure sweeps and cools

180 270 360900

Crank Angle (Deg)

P r e s s u r e


14/133

14



Sequence of events for a 2-stroke enginePT: scavenging

Scavenging continues until intake closes

Cylinder cooling continues

P r e s s u r e

00

90 180 270 360

Crank Angle (deg)




PT: fuel intake


This is the lowest pressure in the cylinder

Fuel is injected just prior to exhaust closure

Open exhaust port drags fuel down

Port closes before any fuel escapes

P r e s s u r e

0

0

90 180 270 360

Crank Angle (deg)


15/133

15



Sequence of events for a 2-stroke enginePT: compression

Fuel injection ceases, ports are closed

Pressure begins to rise

Air-fuel charge is turbulent

Turbulence mixes the air-fuel charge

Temperature rises

P r e s s u r e

00

90 180 270 360

Crank Angle (deg)




PT: ignition

Ignition occurs 5-10 degrees BTDC

Advance gives time to initiate combustionand for flame front travel

Air-fuel charge is superheated

P r e s s u r e

0

0

90 180 270 360

Crank Angle (deg)


16/133

16



Sequence of events for a 2-stroke enginePT: end of cycle

Flame front begins propagatingthrough chamber

P r e s s u r e

00

90 180 270 360

Crank Angle (deg)




PV: start of cycle (TDC)




P r e s s u r e

0

0

25 50 75 100

Swept Volume (%)


17/133

17



Sequence of events for a 2-stroke enginePV: combustion

Flame travels through chamber

Heat is released, pressure rises

Temperature at flame front isabout 3500F

Peak occurs 10-15 deg ATDC

Speed of propagation is critical

Too fast, detonation

Too slow, soft fire

P r e s s u r e

00

25 50 75 100

Swept Volume (%)




PV: power

Combustion is complete

Pressure drives piston down

As volume increases, pressure decreases

P r e s s u r e

0

0

25 50 75 100

Swept Volume (%)


18/133

18



Sequence of events for a 2-stroke enginePV: exhaust blowdown

Piston uncovers exhaust port

Pressure drops more rapidly (blowdown)

Temperature is now about 800F

P r e s s u r e

00

25 50 75 100

Swept Volume (%)




PV: air intake

Intake port is uncovered

Cylinder pressure intake pressure

Fresh air under pressure sweeps and cools

P r e s s u r e

0

0

25 50 75 100

Swept Volume (%)


19/133

19



Sequence of events for a 2-stroke enginePV: scavenging


Cylinder cooling continues

P r e s s u r e

00

25 50 75 100

Swept Volume (%)




PV: fuel intake


This is the lowest pressure in the cylinder

Fuel is injected just prior to exhaust closure

Open exhaust port drags fuel down

P r e s s u r e

0

0

25 50 75 100

Swept Volume (%)


20/133

20



Sequence of events for a 2-stroke enginePV: compression

Fuel injection ceases, ports are closed

Pressure begins to rise

Air-fuel charge is turbulent

Turbulence mixes the air-fuel charge

Temperature rises

P r e s s u r e

00

25 50 75 100

Swept Volume (%)




PV: ignition

Ignition occurs 5-10 degrees BTDC

Advance gives time to initiate combustionand for flame front travel

Air-fuel charge is superheated

P r e s s u r e

0

0

25 50 75 100

Swept Volume (%)


21/133


22/133

22



Sequence of events for a 2-stroke engineCylinder vibration: combustion


273Fuel 213

0 45 90 135 180 2 25 270 315 360Angle (deg)

Rings become fully loaded by gaspressure

May see some vibration resultingfrom combustion

P r e s s u r e




Cylinder vibration: power223 Intake137


0 45 90 135 180 2 25 270 315 360Angle (deg)

Ring noise

P r e s s u r e


23/133

23



Sequence of events for a 2-stroke engine VTCylinder vibration: exhaust blowdown


273Fuel 213

0 45 90 135 180 2 25 270 315 360Angle (deg)

ExhaustBlowdown

P r e s s u r e



Sequence of events for a 2-stroke engine VT

Cylinder vibration: air intake and scavenging223 Intake137


0 45 90 135 180 2 25 270 315 360Angle (deg)

P r e s s u r e


24/133

24



Sequence of events for a 2-stroke engine VTCylinder vibration: fuel intake


273Fuel 213

0 45 90 135 180 2 25 270 315 360Angle (deg)

P r e s s u r e




Cylinder vibration: compression223 Intake137


0 45 90 135 180 2 25 270 315 360Angle (deg)

Fuel ValveClosure

P r e s s u r e


25/133

25



Sequence of events for a 2-stroke engine VTCylinder vibration: ignition


273Fuel 213

0 45 90 135 180 2 25 270 315 360Angle (deg)

P r e s s u r e

Ignition 5-10degrees BTDC




Cylinder vibration: end of cycle223 Intake137


0 45 90 135 180 2 25 270 315 360Angle (deg)

P r e s s u r e


26/133

26



Sequence of eventsfor a 4 stroke engine

Pressure and vibration (PT/VT)

Pressure-Volume (PV)




PT/VT: top dead center


Flame front propagation has begun


Crank Angle (deg)

P r e s s u r e

0

0

180 360 540 720

Fuel 502565Intake 300

137 417 Exhaust

611

12

1 2 3 4Combustion Exhaust Intake Compression


27/133

27



Sequence of events for a 4-stroke enginePT/VT: peak firing pressure

Pressure

Flame front propagation through cylinder

Pressure and temperature rise


Too slow, soft fire

Crank Angle (deg)

P r e s s u r e

0

0

180 360 540 720Crank Angle (deg)

P r e s s u r e

0

0

180 360 540 720

12



137 417 Exhaust

611




PT/VT: power stroke

Pressure

Crank Angle (deg)

P r e s s u r e

0

0

180 360 540 720

12



137 417 Exhaust

611


28/133

28



Sequence of events for a 4-stroke enginePT/VT: exhaust blowdown

Crank Angle (deg)

P r e s s u r e

0

0

180 360 540 720

12



137 417 Exhaust

611

Blowdown Exhaust gases leave through exhaust

valve port to exhaust header andthen to the turbocharger




PT/VT: air intake

Exhaust valveclosure

Crank Angle (deg)

P r e s s u r e

0

0

180 360 540 720

34



137 417 Exhaust

611


29/133

29



Sequence of events for a 4-stroke enginePT/VT: fuel intake

Intake valveclosure

Crank Angle (deg)

P r e s s u r e

0

0

180 360 540 720

34



137 417 Exhaust

611




PT/VT: compression and ignition

Fuel valveclosure

Crank Angle (deg)

P r e s s u r e

0

0

180 360 540 720

34



137 417 Exhaust

611


30/133

30



Sequence of events for a 4-stroke enginePT/VT: end of cycle

Pressure

Crank Angle (deg)

P r e s s u r e

0

0

180 360 540 720

12



137 417 Exhaust

611

Whatsthis?




VT: crosstalk (KVS 412)Engine Cylinders: Phased Vibration VT4:

90 180 270 360 450 540 630 720

K200 - E 9/10/1995 6:51:46 AM

-2

0

2

-2

0

2

-2

0

2

-2

0

2

-2

0

2

-2

0

2

0

P1

P2

P3

P4

P5

P6

This engine has solid lifters 312

672

192

432

72

552


31/133

31



Sequence of events for a 4-stroke enginePV: top dead center

3 COMBUSTION 4 EXHAUST 1 INTAKE 2 COMPRESSION

12

0 25 50 75 1000




PV: air intake


Fresh air enters cylinder

012


32/133

32



Sequence of events for a 4-stroke enginePV: fuel intake & compression

0 25 50 75 100


12

Fuel intake starts BBDC

Turbulence stirs mixture

0




PV: ignition


0

Mixture is compressed andsuperheated

Ignition occurs 10-20 deg BTDC

12


33/133

33



Sequence of events for a 4-stroke enginePV: top dead center


0



34




PV: peak firing pressure


0

Flame travels through chamber

Heat is released, pressure rises

Peak occurs 15-20 deg ATDC

If pressure increase is


Too slow, soft fire

34


34/133

34



Sequence of events for a 4-stroke enginePV: power stroke


0

Combustion is complete

Pressure drives piston down

As volume increases, pressure decreases

34




PV: bottom dead center


0

Exhaust valve opens just before BDC

34


35/133

35



Sequence of events for a 4-stroke enginePV: exhaust


Pressure drops rapidly(blowdown)

0

4 3




PV: end of cycle


0 25 50 75 100

340 25 50 75 100

34 0


36/133

36



Sequence of eventsfor a double actingreciprocating compressor

Head End (HE) compression cycle (PV) Crank End (CE) compression cycle (PV) HE valve events HE and CE pressure-time (PT) HE and CE vibration-time (VT)

GMRC 2003 GAS MACHINERY CONFERENCEBASIC ENGINE & COMPRESSOR ANALYSIS TECHNIQUES 72 2003 DYNALCO CONTROLS

Sequence of events in a reciprocating compressor

HE compression cycle

Pressure

ClearanceVolume

C l e a r a n c e V o l u m e

Ps

Pd

P r e s s u r e

Volume

Swept Volume

Compression

2

1

HECompression1-2

HEDischarge2-3

Discharge3

Suction

HESuction4-1

4

Expansion

HEExpansion3-4


37/133

37


Sequence of events in a reciprocating compressorCE compression cycle


Ps

Pd

P r e s s u r e

Volume

CECompression1-2

1

Compression

Discharge2

CEDischarge2-3

3

Expansion

CEExpansion3-4

Suction 4

CESuction4-1

Swept Volume



PV: HE compression event


Ps

Pd

P r e s s u r e

Volume

2

1

Compression

AD

AP

Discharge Line Pressure (Pd)

Dischargeclosed

AS

AP

Suction Line Pressure (Ps)

Cylinder Pressure (Pcyl)is above Ps and increasing to Pd.Discharge valve opens when Pcylis greater than Pd (2).

Suctionclosed


38/133


39/133

39


Sequence of events in a reciprocating compressorPV: HE suction event


Ps

Pd

P r e s s u r e

Volume

2

1

Compression

3 Discharge

4

Expansion

SuctionAD

AP

Discharge Line Pressure (Pd)

Cylinder Pressure (Pcyl)is below Ps and increasing to Ps.Suction valve closes when Pcyl isequal to Ps (1) at BDC.

AS

Suction Line Pressure (Ps)

Piston Stroke Volume

Dischargeclosed

Suctionopen



Example: HE and CE PV

250

300

350

400

450

500

550

600

0 25 50 75 100


Percent swept volume



40/133

40


A

1

Discharge (D-A)

Suction (4-1)

Sequence of events in a reciprocating compressorPT: HE and CE

HE PT

CE PT

DischargePressure

SuctionPressure

A

1

2

B

Expansion (A-B)

Compression (1-2)

Head End:

Crank End:

Crank Angle (Deg)3600 180

3

C

Suction (B-C)

Discharge (2-3)

4

D

Compression (C-D)

Expansion (3-4)



HE valve vibration

0 180 360

HE Suction

HE Discharge

Gas blowing noise is loudest at valveopening and gradually diminishes asgas velocity through the valve decreases.

2

Suction gas fills the cylinder.2

3

Suction valve is lowered gentlyonto the seat at BDC closingevent is not always visible.

3

1

Suction valve opens(depends on clearance volume)

1

5

5 High pressure gas isdischarged into dischargeline.

6

6 Discharge valve is gentlylowered onto the seat atTDC not always visible.

4 Discharge valve opens(typically the loudest)

4


41/133


42/133

42


Sequence of events in a reciprocating compressorTypical HE PT/VT signature

250

300

350

400

450

500

550

600

0 45 90 135 180 225 270 315 360

--------------

--------------

--------------

--------------

--------------

---------------------------------------

- Scale 3.084 DGF

- Scale 3.084 DGF

- Scale 3.0146 DGF

- Scale 3.0145 DGF

4HS2 VT1

4HS1 VT1

4HD2 VT1

4HD1 VT1



Crank Angle (deg)



Quick Recap

So far, weve talked about the normalbehavior of:

2-stroke, spark-ignited recip engine 4-stroke, spark-ignited recip engine double-acting, reciprocating compressor

Now we know what they are supposed to looklike, we can look at faults


43/133

43



Analyzing Engine Faults

Combustion

Mechanical



Engine faults we can monitor

Port/bridge wear Excessive Emissions

Leaking valves Unbalance

Ignition problems Efficiency

Leaking rings Detonation Valve train (cam, guides, lifters, linkage) Misfire Worn, scored liner and piston Pre-ignition

Frame, foundation vibration Fuel consumption

Oil Pump, water pump problems Fuel cost

Turbocharger faultsEconomic Performance

Main bearings, crank pins Torque

Wrist pin Indicated horsepower

Carbon in portsOperating Performance

Mechanical ConditionCombustion Quality


44/133

44



Combustion

Many of the problems we face with enginesare due to variable combustion

Engines do not fire the same way each cycle



Combustion

Chemical equation of combustion

Engines convert chemical energy to heat Take a simple gas such as Methane (CH 4) Combine it with oxygen and start the reaction

Produces carbon dioxide plus water vapor

and releases heat of about 1000 BTU/ft3

ofmethane consumed

OHCOOCH 2224 22 ++


45/133

45



CombustionIf only it was that simple

Air is primarily O2 (23%) and N 2 (77%) Both are involved in the chemical reaction The combustion process is neither completenor instantaneous

Many intermediate steps and reactions occur This leads to other exhaust products such asNOx, HC, CO and particulates (smoke)



Combustion

Why is combustion so variable?

incomplete mixing in the cylinder difficulty burning lean air/fuel mixtures inconsistent air/fuel charge in each cycle poor fuel quality ignition faults incorrect valve timing

varying ambient conditions


46/133

46



CombustionResults of poor combustion

Firing in each becomes inconsistent, highfires followed by low fires

Stress the engine thermally and mechanically Reduce the life of engine components Waste fuel Increase emissions This costs a great deal of money



Combustion

Typical faults

Unbalance Dead cylinders Early firing Soft firing Detonation Pre-ignition


47/133

47



Engine balance

The manufacturer designed the engine tohandle specific cylinder pressures andtemperatures

Cylinders with high peak pressures developmuch greater mechanical and thermal stress

Engine balancing distributes this mechanicaland thermal stress across the engine to

maximize component life



Engine Balance

Cylinder pressures (balanced HBA)


P1P2

P3P4 P5

P6P7

P8

0

100

200

300

400

500

600

700

800

0 45 90 135 180 225 270 315 360

+2%

-2%

+10%

-10%

Unit2 4/15/2002 9:21:55 AMAll cylinders - In Bank Order

Crank Angle (deg)


48/133

48



Engine BalancePressure rise rate (balanced HBA)

-15

-10

-5

0

5

10

15

20

25

30

35

P r e s s u r e R i s e R a t e ( d p / d )

P1

P2

P3

P4 P5

P6

P7

0 45 90 135 180 225 270 315 360

Unit2 4/15/2002 9:21:55 AMAll cylinders - In Bank Order

Crank Angle (deg)

P8



Engine Balance

Cylinder pressures (unbalanced HLA)C2B-E 6/6/2001 7:22:02 AM


1

2

34 5

6

7

8

0

100

200

300

400

500

600

700

0 45 90 135 180 225 270 315 360

+2%-2%

+10%

-10%

All cylinders - In Bank Order

Crank Angle (deg)


49/133

49



Engine BalancePressure rise rate (unbalanced HLA)

P r e s s u r e R i s e R a t e ( d p / d )

1

3

4 5

6

7

8

-10

-5

0

5

10

15

20

0 45 90 135 180 225 270 315 360

C2B-E 6/6/2001 7:22:02 AMAll cylinders - In Bank Order

Crank Angle (deg)

2 Highly variable



Detonation

Detonation is rapid and uncontrolled combustion.Detonation can lead to rapid failure due to high thermal and

mechanical stress.Causes of detonation:

Mixture too rich Clogged/dirty air intake (air inlet filters, aftercoolers orblowers)

Incomplete scavenging inconsistent fuel composition

Overloaded engine Ignition timing too advanced Highly loaded cylinders in an unbalanced engine are moresusceptible to detonation.


50/133

50



P1

P2 P4

DetonationEngine PT parade (Ajax DPC-720-LE-H-2)

P3 DetonatingCylinder

+2%-2%

+10%

-10%

K203 - E 11/21/1996 2:13:03 PMAll cylinders - In Bank Order

0 45 90 135 180 225 270 315 360Crank Angle (deg)

0

50

100

150

200

250

300

350

400

450

500

550

600




Detonation

Multiple PT cycles for a power cylinder (P3)

0

50

100

150

200

250

300

350

400

450

500

550

500 1000 1500 2000 2500 3000 3500

K203 - E - P3 PT3 11/21/1996 2:13:03 PM

Samples

Misfire Misfire

Detonation DetonationDetonation


51/133

51



Soft Firing

Soft Firing occurs when the pressure in the cylinderrises too late (also called late firing).

The PFP is usually low and late.Causes of soft fires:

incomplete scavenging air/fuel ratio too lean causing slow flame front air/fuel ratio too rich for proper combustion late ignition timing

poor fuel composition



Soft Firing

Engine pressure signature comparisons


P1R

P2R

P3RP4R P5R P1L

P2L

P3LP4L

P5L

0

100

200

300

400

500

600

700

800

0 45 90 135 180 225 270 315 360

1A - E 5/22/1997 10:34:26 AMAll cylinders - In Bank Order

Crank Angle (deg)


52/133

52



Normal

Soft FiringPT: comparison to normal (HBA)

0

Soft (Late)Fire

223 Intake137

242 Exhaust118

273Fuel 213

20905-E Cylinder P8 7/14/1999 6:46:53 AM Period 3

0

50

100

150

200

250

300

350

400

450

500

550

45 90 135 180 225 270 315 360Crank Angle (deg)




Soft Firing

PV: comparison to normal (HBA)

% swept volume

20905-E cylinder P8 7/14/1999 6:46:53 AM Period 3

0

50100

150

200

250

300

350

400

450

500

550

0 25 50 75 100


Normal

Soft (Late)Fire


53/133

53



Soft FiringAnother example comparing engine PTs (CB QUAD)

P2L

P3LP4L

P5L P6L

P1R P2R P3RP4R

P5R P6R

0100

200

300

400

500

600

700

800

900

1000

0 45 90 135 180 225 270 315 360

+2%-2%

+10%

-10%

C402 - E 9/9/1998 12:02:53 PMAll cylinders - In Bank Order - CRC is corrected

Crank Angle (deg)




Early Firing

Early firing occurs when the pressure in the cylinderrises too early.

The PFP is usually high and close to TDC.Causes of early firing:

air/fuel ratio too rich early ignition timing warm air temperature


54/133

54



Early Firingengine pressure comparison

P1R

P2R

P3RP4R P5R P1L

P2L

P3L P4L

P5L

0

100

200

300

400

500

600

700

800

0 45 90 135 180 225 270 315 360

1A - E 5/22/1997 10:34:26 AMAll cylinders - In Bank Order


Crank Angle (deg)



Dead Cylinders

Dead cylinders have no discernablecombustion.

Causes of dead cylinders: ignition problem improper air/fuel charge


55/133

55



Dead CylindersCylinder comparisons of peak pressures (QUAD)

P2L

P3LP4L

P5L P6L

P1R P2R P3RP4R

P5R P6R

0100

200

300

400

500

600

700

800

900

1000

0 45 90 135 180 225 270 315 360

+2%-2%

+10%

-10%

C402 - E 9/9/1998 12:02:53 PMAll cylinders - In Bank Order - CRC is corrected

Crank Angle (deg)


P1L



P2L soft fire

Dead Cylinders

Cylinder comparisons of pressure shape & timing

-180

0

100200

300

400

500

600

700

800

900

1000

-135 -90 -45 0 45 90 135 180

C402 - E 9/9/1998 12:02:53 PMAll cylinders - To Center of Plot - CRC is corrected

Crank Angle (deg)


P1LDead Cylinder


56/133

56



Other cylinders

P2L Soft Fire

Dead CylindersCylinder comparisons of pressure rise rate

-20

-180

-15

-10

-5

0

5

10

15

20

25

30

35

-135 -90 -45 0 45 90 135 180

C402 - E 9/9/1998 12:02:53 PMAll cylinders - To Center of Plot - CRC is corrected

Crank Angle (deg)

P r e s s u r e R i s e R a t e ( d P / d )

Normal

P1L Dead Cylinder



Normal PT

Dead Cylinders

Pressure and pressure rise rate relationship

Crank Angle (deg)

900

1000

C402 - E Cylinder P1L 9/9/1998 12:02:53 PM Period 4CRC is corrected

-103 EXHAUST PORT 100-123 INTAKE PORT 119

-65 FUEL VALVE-125

0

100

200

300

400

500

600

700

800

-180 -135 -90 -45 0 45 90 135 180


P

PT


57/133

57



Dead CylindersPV comparison to normal

0

100

200

300

400

500

600

700

800

900

1000

0 25 50 75 100

C402 - E cylinder P1L 9/9/1998 12:02:53 PM Period 4CRC is corrected

% swept volume

Normal

Dead Cylinder



Pre-ignition

Pre-ignition is the premature combustion of the air/fuelmixture before the normal ignition event (auto-combustion).

PFP may occur before TDC causing excessive force onthe piston, wrist pin, connecting rod and bearings.

The mechanical and thermal stress resulting from pre-ignition can cause cracked heads, torched or seizedpistons.

Causes of pre-ignition hot spots in the cylinder caused by ash or carbonbuild up hot spots created by detonation

early ignition timing is not normally considered pre-ignition.


58/133

58



Pre-ignitionPT comparison to normal

-130 Intake 130-110 Exhaust 110

-77 Fuel-145

0

100

200

300

400

500

600

700

800

900

1000

-180 -135 -90 -45 0 45 90 135 180

5E Cylinder P4 8/15/2002 4:39:48 PM Period 5


Angle (deg)

Normal



Pre-ignition

PV showing 2 crank revolutions

Negative work

Positive workPositive work


59/133

59



CombustionAnalysis summary

Uneven average peak firing pressuresHigh deviation in PFP for cylinderUneven exhaust temperaturesUsually accompanied by higher NOx and HC

Unbalanced

Often audible

High PFP with early PFP angle Very high pressure rise rate compared to other cylinders Often develops a shock wave that is seen in the PT Combustion may make more noise than normal

Detonation

All cylinder average PFPs fall within 10-15% of the engineaverage PFPLow cycle-to-cycle deviation in cylinder PFPPFP angle consistent and at expected locationSimilar exhaust temperatures among power cylinders

Normal

CharacteristicsObservation



Combustion

Analysis summary (cont.)

PFP angle earlier than normal Average PFP higher than normal Higher pressure rise rate when compared to other cylinders (orhistory) Lower exhaust temperature

Early Firing

Type of misfire Average PFP lower than normal PFP angle later than normal Low pressure rise rate when compared to other cylinders (orhistory) May be followed by detonation Increased exhaust temperature

Soft Firing

CharacteristicsObservation


60/133


61/133


62/133

62



Valve Train

Valve Seat

Exhaust Port

Valve Stem

Valve Springs

Valve LifterRocker Arm

Cam Follower

Cam Lobe

Push Rod



Valve Train

Common problems

Mechanical Loose/worn rocker arm Improper lifter clearance Broken springs Incorrect spring tension Worn valve guide Worn or mis-timed cam

Excessive cam gear lash

Leakage Burnt valves Deposits on valve seat Damaged seat Bent valve stem


63/133

63



Valve TrainIncorrect clearance

May cause the valve toopen and close at thewrong time

Valve opening eventcan be noisy theclearance is taken upon the leading edge ofthe cam lobe

Can cause noisy valveclosure if the valve isdropped onto the seat

Crank Angle

L i f t

V i b r a t i o n

ExcessiveLash

Valve openslate & sharp

Valve closesearly & drops

on seat

NormalLift



Valve Train

Hydraulic lifters

Hydraulic lifters maintain correct valve timingand minimize valve train wear over a widerange of operating conditions

Oil pressure within the lifter maintains correctclearances in the valve train

If the lifter collapses The valve may open late and close early The vibration pattern shows impacts atopening and closure


64/133

64



Valve TrainExcessive EV clearance (KVGR with solid lifters)

P 1

P 2

P 3

P

4

P 5

P 6

K1F - E 12/13/1994 11:19:43 AMEngine Cylinders: Phased Vibration VT4:

-2.5

0.0

2.5

-2.5

0.0

2.5

-2.5

0.0

2.5

-2.5

0.0

2.5

-2.5

0.0

2.5

-2.5

0.0

2.5

0 90 180 270 360 450 540 630 720

P1

P2

P3

P4

P5

P6

-2.5

0.0

2.5

-2.5

0.0

2.5

-2.5

0.0

2.5

-2.5

0.0

2.5

-2.5

0.0

2.5

-2.5

0.0

2.5

90 180 270 360 450 540 630 720

P7

P8

P9

P10

P11

P12



Valve Train

Vibration comparison for a leaking EV (KVGR)P1

P2

P3

P4

P5

P6

-2.5

0.0

2.5

-2.5

0.0

2.5

-2.5

0.0

2.5

-2.5

0.0

2.5

-2.5

0.0

2.5

-2.5

0.0

2.5

0 90 180 270 360 450 540 630 720

P7

P8

P9

P10

P11

P12

-2.5

0.0

2.5

-2.5

0.0

2.5

-2.5

0.0

2.5

-2.5

0.0

2.5

-2.5

0.0

2.5

-2.5

0.0

2.5

0 90 180 270 360 450 540 630 720


65/133

65



NormalNormal

Valve TrainPT and PV: leaking exhaust valves (KVGR)

580Intake 294390 Exhaust150

0

50

100

150

200

250

300

350

400

450

500

0 45 90 135 180 225 270 315 360 405 450 495 540 585 630 675 720Angle (deg)


0

50

100

150

200

250

300

350

400

450

500

0 25 50 75 100% swept volume

2 low PFP

22

3 3

3 low expansion

1

1

1 low compression

High exhaust temp



Valve Train

Worn rocker arms (KVGR)K1D - E 2/3/1997 10:52:37 AM

Engine Cylinders: Phased Vibration VT4:

-2.5

0.0

2.5

-2.5

0.0

2.5

-2.5

0.0

2.5

-2.5

0.0

2.5

-2.5

0.0

2.5

-2.5

0.0

2.5

0 90 180 270 360 450 540 630 72090 180 270 360 450 540 630 720

P1

P3

P4

P5

P6

P7

P8

P9

P10

P11

P12

-2.5

0.0

2.5

-2.5

0.0

2.5

-2.5

0.0

2.5

-2.5

0.0

2.5

-2.5

0.0

2.5

-2.5

0.0

2.5

0

P2


66/133

66



Valve TrainWorn cam gear (KVS)

NO-4 - E 2/28/1995 1:38:59 PMEngine Cylinders: Phased Vibration VT4:

P10

P7

P8

P9

P11

P12

-2

0

2

-2

0

2

-2

0

2

-2

0

2

-2

0

2

0

2

-2

P1

P2

P3

P4

P5

P6

-2

0

2

-2

0

2

-2

0

2

-2

0

2

-2

0

2

0

2

-2

0 90 180 270 360 450 540 630 720 0 90 180 270 360 450 540 630 720



Valve Train

Worn cam gear (KVS)410 EXHAUST VALVE161

575INTAKE VALVE 325621FUEL VALVE 536

0

100

200

300

400

500

600

700

800

900

1000

0 45 90 135 180 225 270 315 360 405 450 495 540 585 630 675 720

NO-4 - E Cylinder P12 2/28/1995 1:38:59 PM

Angle (deg)

410 EXHAUST VALVE161575INTAKE VALVE 325

621FUEL VALVE 536

0

100

200

300

400

500

600

700

800

900

1000

0 45 90 135 180 225 270 315 360 405 450 495 540 585 630 675 720

-

-

-

-

-

-

-

-

-

- Scale 2.0

P6 VT4

NO-4 - E Cylinder P6 2/28/1995 1:38:59 PM

Angle (deg)




67/133

67



Valve TrainLeaking fuel valve (HLA)

C2A-E 10/10/2001 6:28:53 AMEngine Cylinders: Phased Ultrasonic ULT:

360135 180 225 27045 90 315

-5

0

5

-5

0

5

-5

0

5

-5

0

5

0

1F

2F

3F

4F

-5

360

-5

0

5

-5

0

5

-5

0

5

0

5

0 45 90 135 180 225 270 315

5F

6F

7F

8F

Hard closures

Leakage



Valve Train

Leaking fuel valve (HLA)

45 90 135 180 225 270 315 360

--------------

--------------

--------------

--------------

-----------------------------

- Scale 2.0

- Scale 4.0

- Scale 4.0

8 VT4

8 ULT

8FV ULT


283Fuel 213

C2A-E Cylinder 8 10/10/2001 6:28:53 AM Period 9

Angle (deg)

0

100

200

300

400

500

600

700

0


Leak asP rises


68/133

68



Valve TrainAnalysis summary

Multiple impact following normal valve closure Excessive noise on opening or closure

Worn rockerbushing

Valve opens late and closes early Impact noises on valve closure

Sometimes see impact on opening Early closing exhaust valves may raise the PV toe

Excessivelifterclearance

Valve opening events are quiet or absent Valve events are similar across the entire engine Closing events are at expected crank angle, singleimpact of short duration

No leakage occurs after valve closure

NormalCharacteristicsFault



Valve Train

Analysis summary (cont.)

Roughness seen in vibration pattern as valve opensand closes

Valve may hang up in the guide and not close at thecorrect time

May see gas leakage if valve does not seat properly

Worn valveguide

Impacts in the vibration as gear teeth pass each other May cause excessive wear on the cam lobe leading torough vibration pattern

When troubleshooting, be prepared to move thevibration transducer around

Cam gearfaults

Impact noises on opening and closure Valve may close late

Brokenvalve spring

CharacteristicsFault


69/133

69



Valve TrainAnalysis summary (cont.)

Multiple impacts on valve closure as valve finds theseat

Look for differences in valve closure across the engine Can be caused by beat-out seat, worn/broken/incorrectspring, worn guide, loose rocker arm, bent valve stem

May see blowby pattern when pressure is high in thecylinder

Impropervalveseating

Blowby pattern appears when pressure rises in thecylinder

Leakingvalves

CharacteristicsFault



Pistons, Rods, Rings and Liners

SOURCE: navsci.berkeley.edu/ ns10/piston.htm


70/133

70



Piston slap

Piston slap occurs when the piston skirtimpacts the liner

Tends to occur after peak pressure when thepressure is high and there are side forces onthe piston

Becomes more pronounced when theclearance in the upper cylinder increases due

to ring wear



Piston Slap

Low frequency vibration showing piston slap (HLA)

-5

0

5

-5

0

5

-5

0

5

-5

0

5

0 45 90 135 180 2 25 2 70 3 15 3 60

C2A-E 6/5/2001 8:23:09 AMEngine Cylinders: Phased Acceleration VTL:

-5

0

5

-5

0

5

-5

0

5

-5

0

5

0 45 90 135 180 2 25 2 70 315 360

1

2

3

4

5

6

7

8


71/133

71



Piston SlapLow frequency vibration showing piston slap (HLA)



283Fuel 213

0

100

200

300

400

500

600

700

0 45 90 135 180 225 270 315 360

--------------

--------------

--------------

--------------

--------------

---------------------------------------

- Scale 2.0

- Scale 6.0

- Scale 4.0

- Scale 20.0

3 VT4

3 VTL

3 ULT

3FV ULT

Angle (deg)


Not always visiblein ultrasonic



Piston Rods

Excessive wrist pin and connecting rodbearing clearances produce impacts at loadreversal in the piston pin bushing

in 4-stroke engines, vibration spikes occurnear TDC

in 2-stroke engines, vibration spikes occurnear BDC

There is usually cycle-to-cycle variability inthe location of the vibration


72/133

72



Piston RodsWrist pin load for a 2-stroke engine

Wrist pin load in a 2 stroke engine

-50000

0

50000

100000

150000

200000

250000

0 45 90 135 180 225 270 315 360 405 450 495 540 585 630 675 720

Degrees

F o r c e ( l b s )

Vibration occursaround BDC

where load is minimal

Inertia

Gas force

Total force



Piston Rods

Wrist pin load for a 4-stroke engineWrist pin load in a 4 stroke engine

-50000

0

50000

100000

150000

200000

250000

0 45 90 135 180 225 270 315 360 405 450 495 540 585 630 675 720

Degrees

F o r c e ( l b s )

Vibration occursaround TDC

where load reverses

Inertia

Gas force

Total force


73/133

73



Piston RodsExcessive wrist pin clearance (KVS)


611FUEL VALVE 502

0

100

200

300

400

500

600

700

0 45 90 135 1 80 225 270 3 15 360 405 450 495 540 585 630 675 7 20

--------------

--------------

-

-

-

-

-

-

-

-

-

- Scale 2.0

P6 VT4

K200 - E Cylinder P6 1/16/1996 9:39:11 AM Period 6

Angle (deg)




Piston Rings

Worn or improperly loaded rings

The presence of gas passing noise whencylinder pressures are high indicates blowby

Be careful though, it could be leakage aroundrings or valves

A damaged liner will prevent rings fromsealing properly

Even moderate blowby may be sufficient tocause a significant rise in the enginecrankcase pressure

Ring fouling prevents pressure from gettingbehind the rings to load them properly


74/133

74



LinersScuffing and scoring

Liner scuffing or scoring is often seen as symmetricvibration spikes around TDC

For a 2-stroke engine, piston rings pass the same pointtwice in one cycle

For a 4-stroke engine, piston rings pass the same point4 times in one cycle

Ring loading affects the degree that each event is seen Wear is usually faster in the upper liner due to highPFP

Crankcase pressure may increase due to blowbyresulting from the liner wear



Liners

Liner groove (KVS, P2, 10 rotations)NO-6 - E 12/21/1995 8:14:16 AM


-2

0

2

-2

0

2

-2

0

2

-2

0

2

-2

0

2

-2

0

2

0 90 180 270 360 450 540 630 720

-2

0

2

-2

0

2

-2

0

2

-2

0

2

-2

0

2

-2

0

2

0 90 180 270 360 450 540 630 720

P2 (MMM)

P2 (1)

P2 (Med 2)

P2 (3)

P2 (4)

P2 (5)

P2 (6)

P2 (7)

P2 (8)

P2 (9)

P2 (10)


75/133

75



LinersLiner groove (KVS)

FUEL VALVE 504

403 EXHAUST VALVE560

0 720

NO-6 - E Cylinder P2 12/21/1995 8:14:16 AM Period 2

Symmetric angle cursorsreveal liner groove

151INTAKE VALVE 345

610

20 340 380 7000

100

200

300

400

500

600

700

800

900

1000

45 90 135 180 225 270 315 360 405 450 495 540 585 630 675

--------------

--------------

-

-

-

-

-

-

-

-

-

- Scale 2.0

P2 VT4

Angle (deg)




Liners

Liner groove (KVS)NO-6 - E 12/21/1995 8:14:16 AM


-2

0

2

-2

0

2

-2

0

2

-2

0

2

-2

0

2

-2

0

2

0 90 180 270 360 450 540 630 720

-2

0

2

-2

0

2

-2

0

2

-2

0

2

-2

0

2

-2

0

2

0 90 180 270 360 450 540 630 720

P2 (MMM)

P2 (1)

P2 (Med 2)

P2 (3)

P2 (4)

P2 (5)

P2 (6)

P2 (7)

P2 (8)

P2 (9)

P2 (10)

Crosstalk from P3 exhaust blowdown

Crosstalk from P1exhaust blowdown


76/133

76



LinersCrosstalk from exhaust event on P3 (KVS)

-2

0

2

-2

0

2

-2

0

2

-2

0

2

-2

0

2

-2

0

2

0 90 180 270 360 450 540 630 720

NO-6 - E 12/21/1995 8:14:16 AMEngine Cylinders: Phased Vibration VT4:

422

662

182

542

302

62

17

257

497

137

617

377

-2

0

2

-2

0

2

-2

0

2

-2

0

2

-2

0

2

-2

0

2

0 90 180 270 360 450 540 630 720

P1

P2

P3

P4

P5

P6

P7

P8

P9

P10

P11

P12

Unphased cursor indicatescrosstalk from other cylinders



Liners

Liner wear (KVS)

90 180 270 360 450 540 630 720-2

0 90 180 270 360 450 540 630 720

-2

0

2

-2

0

2

-2

0

2

-2

0

2

-2

0

2

-2

0

2

0

P1

P2

P3

P4

P5

P6


-2

0

2

-2

0

2

-2

0

2

-2

0

2

-2

0

2

0

2

P7

P8

P9

P10

P11

P12

Chatter as loadedrings pass over wear



77/133

77



LinersLiner wear (KVS)


610FUEL VALVE 504

0

100

200

300

400

500

600

700

800

900

1000

0 45 90 135 180 225 270 315 360 405 450 495 540 585 630 6 75 7 20

--------------

--------------

-

-

-

-

-

-

-

-

-

- Scale 2.0

P7 VT4

NO-6 - E Cylinder P7 3/19/1996 1:28:36 PM Period 2

Angle (deg)




Liners

Liner wear confirmed by symmetric cursor (KVS)NO-3 - E Cylinder P5 5/1/1995 8:06:19 AM Period 2410 EXHAUST VALVE

575621FUEL VALVE 536

405 450 495 540 585 630 675 720

--------------

--------------

-

-

-

-

-

-

-

-

-

- Scale 2.0

P5 VT4

Angle (deg)

161INTAKE VALVE 325

0

100

200

300

400

500

600

700

800

900

1000

0 45 90 135 180 225 270 315 360


128 232 488 592

Symmetric cursor indicatesthe liner is worn.


78/133

78



LinersLiner wear (KVS)

P7

P8

P9

P10

P11

P12

NO-3 - E 5/1/1995 8:06:19 AMEngine Cylinders: Phased Vibration VT4:

P1

P2

P3

P4

P5

P6

-1

0

1

-1

0

1

-1

0

1

-1

0

1

-1

0

1

-1

0

1

0

-1

0

1

-1

0

1

-1

0

1

-1

0

1

-1

0

1

-1

0

1

90 180 270 360 450 540 630 720 0 90 180 270 360 450 540 630 720



Liners

Port bridge wear (HLA)

-10

0

10

-10

0

10

-10

0

10

-10

0

10

0 45 90 135 180 225 270 315 360

-10

0

10

-10

0

10

-10

0

10

-10

0

10

0 45 90 135 180 225 270 315 360

C2A-E 10/10/2001 6:28:53 AMEngine Cylinders: Phased Ultrasonic ULT:

1

2

3

4

5

6

7

8


79/133

79




283Fuel 213

0

100

200

300

400

500

600

700

0 45 90 135 180 225 270 315 360

--------------

--------------

--------------

--------------

-----

------------------------

- Scale 2.0

- Scale 10.0

- Scale 10.0

4 VT4

4 ULT

4FV ULT


Angle (deg)


LinersPort bridge (HLA)

Excessivering noise



Ignition Systems

Provide the energy to begin the chainreaction in the air/fuel mixture and consistsof

Power supply Timing circuit Distribution mechanism Transformer

Spark plug


80/133

80



Ignition SystemsIgnition Primaries

P1LP2L P3LP4L P5L P6LP1R P2R P3RP4R P5R P6R

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

0 45 90 135 180 225 270 315 360

C402 - E Cylinder P1L 07/03/1997 8:07:43 AM

V o l t a g e ( V )

Crank Angle (deg)

TDC

Voltages shouldbe similar

ZenerGates



Ignition Systems

Ignition secondaries

0 1 2 3 4 5

S e c o n d a r y V o l t a g e

Time (ms)

CapacitorDischarges

Indication ofionization voltage

Coil ring down

Arc Duration

Plug Stops Firing


81/133

81



Ignition SystemsTypical ignition secondary patterns

C402 - E 09/09/1998 12:02:53 PM

Ignition timing angle = 5.7



0

0

0

0 1 2 3 4 5

P4LL(Med 1)

P4LR(Med 1)

P5LL(Med 1)




0

0

0

0 1 2 3 4 5

P5LR(Med 1)

P6LL(Med 1)

P6LR(Med 1)



Ignition Faults

Timing

Advanced timing can cause early combustion early and increased PFP detonation lower exhaust temps

Retarded timing can cause delayed combustion

late and low PFP misfires/soft fires higher exhaust temperatures


82/133


83/133

83



Ignition FaultsCoils

Check for correct polarity Look at coil ring down to assess coil windingcondition



Ignition Faults

Two bad coils plug did not fire







-250

0

-250

0

-250

0

-250

0

-250

0

-250

0

0 1 2 3 4 5

C402 - E 9/9/1998 12:02:53 PM Secondary Ignition (Y Axis: mV -- X Axis: ms)

P1LL

P1LR

P2LL

P2LR

P3LL

P3LR







-250

0

-250

0

-250

0

-250

0

-250

0

-250

0

0 1 2 3 4 5

P1RL

P1RR

P2RL

P2RR

P3RL

P3RR


84/133

84



Ignition FaultsReversed coil

-100

0

100

200

-100

0

100

200

-1

Documents

Basic Engine and Compressor Analysis