Hellppppp!

Ok i think i have a major issue with my 2001 pontiac grand am gt 6 cylinder automatic. the first thing i noticed is one day i got in it turned it on and it instantly revved up to almost 4 grand and stayed there so i shut it off and it stopped, but later i cranked up and it did it again and i put it in drive and hi ho silver it was taking off. it hasnt done that in a week but now anytime i drive it shifts very late as appossed to normal and when it does finally shift it shifts violently. i changed out the spark plugs and plugs wires. dropped the tranny fluid and changed it and there was no particles or nothing like that in it. the research i have done points the transmission vacuum modulator but i dont know if this one actually has one of those devices because i cant find replacement anywhere any advice is appreciated. also my cig lighter isnt working at all too :).

Hey! Welcome to AF!!

hi ho silver! AWAY!

just kidding heh...

it may be your throttle position sensor, that could cause some problems, it could be open for some odd reason or if you had a electrical issue it might of messed it up to stay open

if its doing really hard shifts I wouldnt recommend running it anymore as you could really do some damage to the transmission all together

No SES light & engine code has came up?

Yeh hi ho silver is what it was feeling like. i havent drove it since. it has no check engine or service engine lights. now with throttle position sensor could that be detected with computer diagnostics. cause thats what i was going to do today with a repair shop down the road.

Sounds like the throttle cable was/is stuck.

If you shifted it into gear while the RPMs was high, you could have broke your trany.... :eek:

and welcome to AF.

I greased the throttle cable and that was not the issue. I did not shift into gear while the rpms are high i know better than that they were about at 1.5 when i shifted. i was told that this model does not have a transmission vacuum modulator it has what is called throttle position sensor is that correct? my mechanic said it was the cat converter causing the issues which i doubt so i am going to clean it out today. any help is appreciated.

yea, use some electronics cleaner found at any auto parts store, make sure you disconnect the connector.. spray both the TPS and the connection that goes into it with the cleaner and let dry, should be good...

with the TPS sensor is my only guess but its not really logical... cause the throttle isnt technically "open" .. the TPS only tells the engine how much it is open but dunno...

and if Im correct, I think if it was the cat you wouldnt actually be able to get up to a certain RPM if the cat was clogged ...

your IAC (idle air control) which should be located right above the TPS could also be at fault... not sure how much it could open up but if you wanna check that too you can also... good carbon cleaner (watch for fumes!) will take the cake in most cases =)

it could be possible its just open and suck with carbon or the actual sensor is messed up but not likely if you havent moved the spring around,

btw, dont turn or adjust the spring in any way, just clean and place it back in (The IAC valve, located above TPS sensor)


I do have one question, if you were to start it right now without going anywhere .. what would the 'idle' rpms be in your case .. 1500?

yeh now that is what it does about 1500. so i need to clean the tps cause i have already ordered another one and i was thinking of ordering a iac just to be sure. and i am going to clean the cat anyways just for good measure.

I would replace those sensors just yet. :grinno:

You can easily test them to see if they are faulty!

Your idle issues probly is from the IAC, being carboned up inside the passage way. Cleaning it usualy helps.

Thier's procedures for testing these in the Tips and Maintenance subforum (http://www.automotiveforums.com/vbulletin/forumdisplay.php?f=2148). :thumbsup:

Also you realy cant clean your Cat Conv out , other then blowing it out. Any solvents could possibly ruin it thats not good.

Good Luck

ps- even a vacum leak can cause some high idling. ;)

wild card, the issues you are having can all be directly related to a large vaccume leak. Check all your rubber hoses and all around your intake manifold. Spray starter fluid at the suspected areas while the engine is idling. If you spray into the leaking area the engine will rev.

Good Tip Jim !

Carb cleaner also works, starting fluid.... it can be dangerous if it gets on the manifolds, the stuffs pretty darn flamable ! :smokin:

true, some of the bung fitments might have lost their hold and are allowing air to pass through... they can be found in a few places,

PCV Valve hose that goes back, top of the intake manifold, and then around back to some O2 sensor ... and the other is located right on the rubber air intake and goes to the back valve cover... I know mine are at least leaking a bit but not serious

worth the try to check em too, but also the previous method of the carb cleaner will also work :D

Let us know how it goes!!

Alright guys i replaced the tps and that did not change anything my dad and i replaced the cat too still nothing. my father wants me to pick up a egr valve but i dont know if that has anything to do with it. my car is now idling correclty but there is still the issue of if not wanting to shift and it almost sounds like it is gasping for air if that makes any sense. btw i appreciate all the replies i had no idea but now i am much better off.

you are still describing a massive vacuume leak. Quit wasting your money senselesly replacing parts and go find the real issue

The EGR valve wouldn't cause this, unless it was cracked and leaking air into the manifold (but you'd hear exhaust noise).

If you're worried about spraying flamable liquids on hot metal parts, use a propane torch, turn the knob up all the way (not lit, of course) run it around all vacuum lines/hoses and around the intake manifold. I have used intake cleaner hundreds of times to find leaks and never had a fire, but it is possible.

It's possible the IAC valve was sticking open, and now isn't. I had a '02 Ford escape that idled at 4,000 RPM. After I took the valve off, found nothing wrong, and put it back on, it idled @ 800 RPM. I installed a new valve anyway since it had a code for it. Havn't seen the vehicle again so i figure it's fixed.