Testing the Throttle Position Sensor

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Forum BMW Model Specific 3 series (E21, E30, E36, E46, E9x, F30) 1991 - 1999 (E36)

Testing the Throttle Position Sensor

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04-13-2012, 04:06 PM

Join Date:Location:Posts:My Cars:

Nov 2009Madison, WI

433'96 328ic, '07 328xit

Testing the Throttle Position Sensor

I've been trying to track down an intermittent

problem that causes a hesitation and infrequently

causes the engine to stall. Also, on initially

pressing the accelerator from idle the revs dip then

rise - the car doesn't go so low as to stall, but

there is a noticeable delay in 'revving'. When thecar has stalled in the past it has been during

cruising or when coming to a stop.

All my diagnosing to date has come up empty. I've

tried various routine-maintenance type things

including much of what is posted on the 'official

bogging, hesitating, etc. thread'.

The current focus of my attention is the TPS. In

doing some internet research it seems that this

device could be causing my problems. However,

when I go through the testing procedure, I get a

bit confused.

Across terminals 1 and 3 I get 5 kohm - supposed

to get approx. 4 Kohms.

Across terminals 1 and 2 I get between 1.5 and 5

Kohms.

So this seems correct - although with the 1/2 test,

no matter how slow I turn the throttle the

multimeter occassionally 'OF'd' and or zeroed out.

Could this be a symptom of a faulty TPS, or just an

idiosyncracy of my meter?

What is more is that with the ignition on I get

basically zero volts across terminal 3 and itsground (which I assume is the female counterpart

in the harness).

I went on to test the car's running with the TPS

unplugged. I couldn't really say I noticed a

#1

Member

morzada

Forum

ing the Throttle Position Sensor http://forums.bimmerforums.com/forum/showthread.php?1820893-Testi...

n 4 10.04.2013 19:05


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difference - although initially my ASC light was on (that TPS was still plugged in) - and no check

engine light. I shut off the car, unplugged them both - no change. Plugged them both back it,

ASC went off. Unplugged just the regular TPS and then got the check engine light.

I checked the codes, got a fault for the TPS and a fault for the Crank Sensor. I've had the crank

sensor fault before, but have replaced the CPS twice in the past.

Is this telling me anything, or am I destined to stay frustrated?

Just for the record, here is my recent maintenance list:

Replaced Plugs/Boots

Replaced Coils (replaced in stages with some from a swap meet)

Replaced Crank Angle Sensor (and harness)

Replaced Cam Angle Sensor

Replaced Fuel Filter

Replaced Both Front O2 Sensors

Replaced Water Pump, T-stat, bunch of hoses

Cleaned ICV

Cleaned MAF

Went over entire vacuum system - found the hose to the fuel pressure regulator was

disconnected.

Replaced Fuel Pump Relay

Replaced DME RelayChecked all the Chassis Grounds (all good)

Checked Trunk Lid Wiring (all good)

Serviced Injectors (caps, filters, o-rings)

Replaced Valve Cover Gasket

Replaced Oil-Filter Housing Gasket

Replaced Fuel Pump

Last edited by morzada; 04-13-2012 at 04:33 PM.

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04-13-2012, 05:41 PMJoin Date:Location:Posts:My Cars:

Oct 2006Greenville, NC

1,6741997 328i

convertible

The TPS is a potentiometer. It has a conductive strip whose ends are connected to terminals 1

and 3. Terminal 2 is connected to a wiper that slides on the conductive strip as you open the

throttle. When it wears out, the wiper will not make consistent contact and you will get the

action that you described.

#2

Member

RNeil

no matter how slow I turn the throttle the multimeter occassionally 'OF'd' and or zeroed out.Could this be a symptom of a faulty TPS, or just an idiosyncracy of my meter?

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04-18-2012, 06:53 PM


Aug 2011Bay Area, CA

851997 M3 Coupe

Also your TPS is out of spec. I replaced mine this morning since I was getting 1.5k ohms to 6k

ohms. Spec is 1k ohms to 4k ohms, which is exactly what my new one produces.

Not exactly sure what you mean by that. Are you plugging one test lead to the TPS and the

#3

Member

anotherhaus

What is more is that with the ignition on I get basically zero volts across terminal 3 and itsground (which I assume is the female counterpart in the harness).


n 4 10.04.2013 19:05


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other to the harness? It doesn't work that way. Voltage only comes through the harness (then

into and back out of the TPS). Both of your meter's test leads go into the harness; the hole that

mates to pin 3 on the TPS is the + lead, and the hole that mates to pin 1 is the - lead. I read

5.01 volts across those two.

Fortunately a new TPS is inexpensive and only takes a minute to bench test and install.

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04-28-2012, 08:35 PM


Nov 2009Madison, WI

433'96 328ic, '07 328xit

Anotherhaus - didn't see your reply until about 20 minutes ago when it was pointed out to me in

a different thread.

With your explanation I was able to verify that I have 5V out of the harness (seems that the

manual could have been a little clearer about that test - I don't speak good electrician). Off the

car my resistance read up to 6Kohms, too.

I also just happened to have a new TPS on my shelf which I just installed (was/am sidetrackedby what now appears to also be a fuel pressure issue).

Fingers crossed. Test drive tomorrow!

Last edited by morzada; 04-28-2012 at 08:49 PM.

#4

Member

morzada

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04-28-2012, 08:57 PM

Join Date:Location:

Posts:My Cars:

Dec 2008Woodstock, MD

2491993 325i

I'm curious about the results. I started another thread on something similar. A while back I was

getting TPS codes. The TPS checked out okay, but I replaced it, and the TPS code went away, so I

assume there was an intermittent bad contact. However, if I hit the throttle hard from idle the

revs dip before doing anything. There was also a loud whooshing noise coming from the

throttlebody. I assumed the two are related, but now I'm wondering if the loud whooshing noise

is normal, and a marginal TPS (particularly near idle) is is simply causing my car not to give it

fuel fast enough if you hit the gas hard.

#5

Member

hpmaxim

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04-29-2012, 12:07 AM


Sep 2010Chicago, IL.

9941996 328is

You can also check voltage between terminal 2 and ground

~.45 volts throttle closed, ~4.5 volts throttle open

Finding someone with a live data scanner is best, as you can make sure the DME is actually

getting thos signals

1996 328is Sport package

S52 cams/M50 manifold

Conforti CF Intake

Conforti Tune

3.91 LSD

#6

Member

DJCarbine


n 4 10.04.2013 19:05


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Testing the Throttle Position Sensor