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BAD THROTTLE POSITIONING SENSOR SYMPTOMS

Posted By: Magnumguy

BAD THROTTLE POSITIONING SENSOR SYMPTOMS - 02/14/09 06:51 PM

My 97 Dak, V6, when you shift, the rpm's go up, drop and if you hold the clutch in will go up and down, sometimes going up to around 2000, then eventually drop off. Idles fine when it finally settles down, sometimes the rpm's will stay up for quite awhile. I've had the throttle body off and cleaned it. Not really much difference.

It doesn't throw the check engine light on.

Is it the TPS or the IAC?
Posted By: MoparJoe

Re: BAD THROTTLE POSITIONING SENSOR SYMPTOMS - 02/14/09 07:21 PM

Sounds like the IAC is hanging up, the TPS usually causes a 2-300rpm surge while driving at a steady speed.
Posted By: Magnumguy

Re: BAD THROTTLE POSITIONING SENSOR SYMPTOMS - 02/14/09 07:30 PM

It'll rev up and drop, but not what I call surging. I runs smooth, just up and down, eventually leveling out.
thanks
Posted By: 383man

Re: BAD THROTTLE POSITIONING SENSOR SYMPTOMS - 02/15/09 03:01 AM

TPS will cause a higher surging idle and also a hesitation like a bad accelerator pump does in a carb. Ron
Posted By: 10sec440

Re: BAD THROTTLE POSITIONING SENSOR SYMPTOMS - 02/15/09 04:01 AM

TPS's RARELY go south,though I'm not saying it's not that...check your pcv valve, maybe even pinch it off and drive it, see if it goes away. A pcv is after all a controlled vacuum leak. The other possibility is the intake pan.
Posted By: slantzilla

Re: BAD THROTTLE POSITIONING SENSOR SYMPTOMS - 02/15/09 04:20 PM

Dakota's have had a problem with the TPS for a long time. I had the surging issue on my R/T when I got it. Saw a post on the Dakota-Durango board about the TPS problem.

I talked to the Dodge dealer about it and they wanted to do all kinds of stuff. I asked about the TPS and they said they had never replaced one.

I replaced mine myself and the problem went away. My buddy in Nebraska had the same issue with his 2001 V-6 Dakota. Both ours are auto trans though.
Posted By: Magnumguy

Re: BAD THROTTLE POSITIONING SENSOR SYMPTOMS - 02/15/09 06:21 PM

Thanks.

I wonder if there's not a way to test them.
Posted By: slantzilla

Re: BAD THROTTLE POSITIONING SENSOR SYMPTOMS - 02/15/09 06:49 PM

Quote:

Thanks.

I wonder if there's not a way to test them.




You should be able to connect an ohm meter to it and watch the sweep and check for dead spots I would guess.
Posted By: Magnumguy

Re: BAD THROTTLE POSITIONING SENSOR SYMPTOMS - 02/16/09 06:19 PM

I'll probably go out and buy one, they're like $40. Probably eventually have to get one.
Posted By: Duster_Dude

Re: BAD THROTTLE POSITIONING SENSOR SYMPTOMS - 02/17/09 02:53 PM

From what you've described it sounds like the IAC has failed or is failing, that would make the RPM'S higher than normal. Just make sure you don't have any vacuum leaks, that's a good starting point.

TP sensors can cause all sort's of havoc. Their main characteristic is usually a hesitation like 383man said.
The best way I've found to check a TPS is via a DC voltage / waveform test.
Although, you have to have access to something like a Snap-on Vantage meter or a lab scope that shows waveforms.
But as long as you have a good multimeter, you can find out what each sensor is doing by reading the ohm's.
Here's a video I found that might help in your diagnosis....

http://www.wonderhowto.com/how-to/video/...l-motor-267188/
Posted By: Magnumguy

Re: BAD THROTTLE POSITIONING SENSOR SYMPTOMS - 02/17/09 03:44 PM

thanks guys!!
Posted By: RodStRace

Re: BAD THROTTLE POSITIONING SENSOR SYMPTOMS - 02/17/09 04:46 PM

Sounds like you have the info to check and fix. Just wanted to add a little history.
Throttle position sensors used to commonly fail at a certain point, usually at less than a 1/4 throttle. What would happen is that the car would normally be driven at normal speeds and your foot would wiggle just a bit over the bumps. Since the sensor was similar to a fuel sending unit, the spot where all this took place would get rubbed down. They were fairly easy to check, you would just open the throttle slowly while watching the return voltage. It would raise normally, then drop out, then raise again. It would act like an ignition dropout or a fuel starve at that point. Fine above and below.
The AIS causes the idle speed waver. The early ones were pretty slow and tended high to avoid stalling. Newer ones are much better, but if you have a vacum leak or other issues causing the idle speed to be outside normal range, it has to work harder and learn to keep the idle normal. The factory tends to keep the throttle plates open during shifts, to match engine speed and to keep from closing and opening the throttle and dumping that enrichment fuel (emissions and MPG).
Posted By: Magnumguy

Re: BAD THROTTLE POSITIONING SENSOR SYMPTOMS - 02/25/09 05:32 PM

Bought an IAC, problem solved !!!
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