TPS (throttle position sensor) Symptoms

AstroManiac · Post by **AstroManiac** » Wed May 14, 2008 4:38 pm

What are some of the symptoms of a bad TPS or that it may be going out???
My neighbor's 98 Astro AWD "W" engine, idles fine & sometimes it accelerates fine, "sometimes", but other times it drops to nothing or almost dies! Sometimes, if it is acting this way, you can sort of feather the throttle or lightly pump it & it will pick up & go!
Fuel pressure is 60 psi, new fuel filter, no codes!
Any ideas???

SoCalli V8 · Post by **SoCalli V8** » Wed May 14, 2008 10:03 pm

It may stumble as you give it gas, through a favorite freeway cruising speed and throttle position, because the potentiometer contacts are worn in at that point.

Its very easy to test with a digital volt meter, Google the test proceedure because I don`t have time right now to type it all out.

You are looking for a clean voltage sweep with no drop-outs from 1 volt to 4.5 volts, while opening the throttle slowly.

crash · Post by **crash** » Thu May 15, 2008 4:51 am

the symptoms can be very similar to the stumbles these vans have on cool wet (damp) days. where it seems that they are not getting fuel delievered properly. with the moisture that gets in the caps and arching of wires. I think my 99 TPS is going bad also. I have the same symptoms as you describe, it hasn't completely died .. only stumbled... yet.

I haven't had the time to get mine resolved but at the moment I have two other vehicles to drive if it get's really bad.

Smiliesafari · Post by **Smiliesafari** » Thu May 15, 2008 5:28 am

You guys might want to clean your throttle bodies. Dirty TB's also cause those synptoms. $\:D/$

Cobra · Post by **Cobra** » Thu May 15, 2008 7:13 am

funny i have similar symtoms i'm going to be checking the TPS today the TB will wait for another day when i get rid of the restrictor in there.... :-k

LaGrasta · Post by **LaGrasta** » Thu May 15, 2008 8:05 am

How do you clean the TPS?

AstroManiac · Post by **AstroManiac** » Thu May 15, 2008 11:00 am

My neighbor replaced his intake manifold gasket set about 3 months ago & used some type of spray cleaner to clean the throttle body. He did not remove the TPS when he cleaned it though!

AstroManiac · Post by **AstroManiac** » Thu May 15, 2008 11:37 am

We "googled" "TPS test" & it was amazing how much stuff came up!
One other thing he said he sort of cleaned was the MAP sensor.
One of the TPS test articles that came up, said a bad MAP sensor could cause similar results as the TPS too!
So as soon as he gets the time, we'll check both of them out!

SoCalli V8 · Post by **SoCalli V8** » Thu May 15, 2008 10:08 pm

Don`t bother trying to clean a map sensor, but a throttle body clean with brake cleaner and replacing the problematic tbi base gasket would be a worthwhile job to do.

Fill in your signiture so that we know where your at, and what you got.

AstroManiac · Post by **AstroManiac** » Fri May 16, 2008 9:10 am

We checked the TPS & it works fine. We also checked the MAP & it is OK according to the test.
This morning, it fired up & ran great... UNTIL... it warmed up & then the hesitation/die-ing was back.
Warmed up it still idles great, but any movement of the throttle pedal & it hesitates or dies.
No codes!
Is there a "temp sender" we need to check???

kings-x59 · Post by **kings-x59** » Fri May 16, 2008 9:37 pm

There is a coolant temp sensor. If it was bad I think you'd get a code.
Have you looked at your ignition system? Distributor cap, rotor, plug wires, spark plugs? When were they last replaced.
If you are getting no codes its fuel delivery, ignition or vacuum that is the issue. Your fuel pressure is good so that leaves two things to search.

kings-x59 · Post by **kings-x59** » Fri May 16, 2008 9:41 pm

oh, P.S. LeGrasta,
you can't clean a throttle position sensor... well you could, but it wouldn't work any more.

SoCalli V8 · Post by **SoCalli V8** » Fri May 16, 2008 9:49 pm

Please FILL OUT your Signiture, so that the OBD 1 and 2 technical guys here, can help you further......

AstroManiac · Post by **AstroManiac** » Sat May 17, 2008 12:50 pm

Hey SoCalli V8, I don't know if you're asking me to fill out my signature, but if you read my first post in this thread, it states this Astro is my neighbor's, it is not mine!
So I'm not putting someone else's vehicle in my signature!

Anyway... it is a 98 Astro AWD, 4.3 "W" engine, so it is definately OBD II, as OBD I was only thru 95.
Thanks...

AstroManiac · Post by **AstroManiac** » Sat May 17, 2008 1:02 pm

Almost forgot, the "cap, rotor, wires, plugs" were replaced with official GM parts when he did the intake gasket a little bit ago.
Everything was working great & then this problem just started a couple weeks ago!
Note - when it died 2 weeks ago & he had it taken home on a rollback, it had a "Random Misfire" code, I think it was P0300 & a "Bad O2 Sensor After The Cat" code, I think P0147 or close to that!
He replaced the O2 Sensor & re-checked ALL of the wires/plug-ins/connections & everything looks great!
He fired it up & it ran better than ever, until it warmed up, then it started the whole "hesitation/dieing thing".

98 Astro AWD 4.3 "W" engine

Chevy & GMC Vans

Chevy & GMC Vans

TPS (throttle position sensor) Symptoms

TPS (throttle position sensor) Symptoms

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