dikk Posted January 9, 2005 Report Share Posted January 9, 2005 As of yesterday my '90 GP is acting very strange. It dies (without me noticing) when i'm at a stop sign or idling, like when i stop to change to reverse. When i start the car again the engine revs up abnormally high to somewhere between 2-3000 rpm as if i would have the gas pedal half way down, then the rpm slowly drops somewhat. There are no problems at all when i'm driving at normal speeds, just when im stopping or going very slow. Does anyone know what's causing this? I have looked around the forum and found topics about similar problems, but it doesn't seem to be the exact problems that i have. My dad has encountered the same problem with his GP (same year/engine as mine) a couple of times but he says that it went away after a while. Please give me all the possible solutions and please do not use lots of abbreviations, if possible. Quote Link to comment Share on other sites More sharing options...
GP1138 Posted January 9, 2005 Report Share Posted January 9, 2005 First, did you use the Search function? Second, the Throttle Position Sensor (TPS) is a likely culprit. It may have lost it's ability to control the idle speed of your car, therefore causing the stall. Try replacing that with a known good one. I will edit this with a diagram later if need be. Quote Link to comment Share on other sites More sharing options...
dikk Posted January 10, 2005 Author Report Share Posted January 10, 2005 Thanks for your answer. And yes, i did use search. From what i could see, no one had the exact problem as i have. Do you have any general idea what this TPS-thing might cost and where on the web i can order one? I guess it won't do with anything less than a GM-specific part. And is it possible that this is something temporary that might go away with a bit of luck, as my dad said? That seems quite unlikely though... Quote Link to comment Share on other sites More sharing options...
terryk2003 Posted January 10, 2005 Report Share Posted January 10, 2005 have you checked the vacum hoses?...if you havent, that might be a good place to start... Quote Link to comment Share on other sites More sharing options...
dikk Posted January 10, 2005 Author Report Share Posted January 10, 2005 I haven't checked anything yet as i don't know what to look for, but thanks for the tip. Keep 'em coming! Quote Link to comment Share on other sites More sharing options...
no1kicker Posted January 10, 2005 Report Share Posted January 10, 2005 the IAC might be something to look at too. Quote Link to comment Share on other sites More sharing options...
slick Posted January 10, 2005 Report Share Posted January 10, 2005 the IAC might be something to look at too. My first guess. Also, check the TPS, any and all vaccum lines, intake gaskets. Quote Link to comment Share on other sites More sharing options...
GP1138 Posted January 10, 2005 Report Share Posted January 10, 2005 OMFG! I meant to say Idle Air Control valve (IAC, like they mentioned above)! I'm such a retard! The throttle position sensor will most likely have very different failure symptoms. Sorry to mislead you at all. :oops: :dammit: IAC costs about $50 or so at Autozone, and one you get there should do just fine. Quote Link to comment Share on other sites More sharing options...
slick Posted January 10, 2005 Report Share Posted January 10, 2005 OMFG! I meant to say Idle Air Control valve (IAC, like they mentioned above)! I'm such a retard! The throttle position sensor will most likely have very different failure symptoms. Sorry to mislead you at all. :oops: :dammit: IAC costs about $50 or so at Autozone, and one you get there should do just fine. Junkyard IAC is cheaper. Usually cleaning them up some helps a ton. Quote Link to comment Share on other sites More sharing options...
Canada Posted January 10, 2005 Report Share Posted January 10, 2005 Any DTCs? Lets start there before the shotgunning of parts takes place. Quote Link to comment Share on other sites More sharing options...
slick Posted January 10, 2005 Report Share Posted January 10, 2005 Lets start there before the shotgunning of parts takes place. But thats the fun part... Quote Link to comment Share on other sites More sharing options...
Slade901 Posted January 10, 2005 Report Share Posted January 10, 2005 The TPS and IAC are usually located near each other on the throttle body. The last time I check the TPS was $18 and IAC $29 at autozone. I don't think you can clean the TPS but you can try cleaning the IAC and clean the spot where the IAC goes in because it would be full of gunk. What about your battery is it still holding charge pretty good? Quote Link to comment Share on other sites More sharing options...
dikk Posted January 10, 2005 Author Report Share Posted January 10, 2005 Ok, thanks everybody for your kind tips and advices. I checked the electric connections to the "IAC" and it doesn't seem to be anything wrong there. No oxidation or anything but a bit of 5-56 or something on the connectors might be good anyway, or? The battery should be fine...the meter is usually in the middle of the range and it still is. I tried some injection cleaner (it has to be done anyway, so..) and it may be my imagination but i actually think it works a bit better now. It died on me as usual in the parking outside my work today, but when i started the car again the idle seemed better. No revving up to 3000rpm, although the idle was still a bit unstable. What do you think of that? Quote Link to comment Share on other sites More sharing options...
phantomshado Posted January 10, 2005 Report Share Posted January 10, 2005 look for vac leaks, that and regap the plugs. it'll do wonders. Quote Link to comment Share on other sites More sharing options...
slick Posted January 10, 2005 Report Share Posted January 10, 2005 look for vac leaks, that and regap the plugs. it'll do wonders. I was thinking vacuum leaks as well. Quote Link to comment Share on other sites More sharing options...
dikk Posted January 11, 2005 Author Report Share Posted January 11, 2005 Any good tips on exactly how i check this? The vacuum hose is the fat one near the battery that goes from the front...right? Quote Link to comment Share on other sites More sharing options...
91cutty Posted January 31, 2005 Report Share Posted January 31, 2005 By any chance, do you have a bad battery or did you disconnect the power recently. Sounds EXACTLY like what my car was doing when it needed an idle re-learn. Probably the reason your dad's problem went away after a while is cause the ECM re-learned the idle, but that takes a while and it's a pain to drive like that. I would recommend trying a re-learn before dumping any money into your car. I may be wrong but this situation sounds all to familiar. (Had to do an idle re-learn 3 times myself already) Quote Link to comment Share on other sites More sharing options...
joberlee Posted February 1, 2005 Report Share Posted February 1, 2005 I had a 2.8 regal that did exactly the same thing. Take out the 2 bolts/ screws that hold the IAC onto the throttle body. Remove the IAC and clean the hell out of it. The end where it seats is painted and the paint gets funky after a while, I found a little bit of emery cloth worked well for final cleanup. Then clean the hole where the IAC mounts with a paper towel and then some carb cleaner. Don't forget to clean out the pasages that go to and from the IAC, they are usually full of carbon gunk. When I worked at NAPA I used to sell a ton of these and never had one come back. I have seen the plunger actually break loose from the control motor :shock: , so make sure the rod is still securely attached to the motor. Should take maybe 45 minutes at the most. Also a good time to clean out the gunk from the throttle body and intake. Soak down the intake while you're working on it and let it sit while for at least about 5 minutes. Treat it like its flooded when you start it, it will run like shit for a minute or two and blow some nasty looking stuff out the exhaust. About 2 cans of the cheap ass carb cleaner from autozone worked wonders on my buddies 90 Grand Prix 3.1 Have fun and good luck Quote Link to comment Share on other sites More sharing options...
dikk Posted February 7, 2005 Author Report Share Posted February 7, 2005 91cutty & joberlee> Thanks guys, I will try your tips. I did remove the IAC and tried to clean it but i didn't dare to open the throttle body. So that may be the culprit as well...? I also was at a mechanic recently and he got the error #35 on his computer...he adviced me to use some two stroke-oil (?) in the gas for a while to lube up the system, but it still runs like shit and dies when the engine is warm. At least, he didn't charge me anything! Quote Link to comment Share on other sites More sharing options...
joberlee Posted February 7, 2005 Report Share Posted February 7, 2005 Clean the throttle body and intake out. It's not very hard to do and is definently worth the effort. As for the two stroke oil in the gas, I don't know how good that is for the injectors... You may have an intake leak between the upper and lower intakes. The gaskets are cheap but it's kind of a pain to put back together, the worst parts are the brake booster vacuum line (big threaded fitting on the back edge of the intake) and the EGR valve hose that connects to the exhaust crossover (these have a tendancy to want to twist and kink sometimes). other than that, not really a hard job, just time consuming. Should take a couple of hours. To check for an upper intake leak; you can, while the engine is running and warm, spary something like WD-40 around the intake edges and underneath and see if the engine smooths out. This will effectively replace the extra air with something at least somewhat flamable. Do you know how to check your own error codes? Joe Quote Link to comment Share on other sites More sharing options...
dikk Posted February 8, 2005 Author Report Share Posted February 8, 2005 I have checked for leaks, and didn't find anything so i guess we can exclude that. I don't know if that's a good or bad thing really. It would be great to pin down the problem even if it is a pain to fix. I don't know that about the error codes (in fact, i hardly know anything about cars...) but i would be grateful if you could tell me how to check them myself. Sounds good...i have a feeling that the mechanic won't be that kind-hearted the next time.. Quote Link to comment Share on other sites More sharing options...
joberlee Posted February 8, 2005 Report Share Posted February 8, 2005 To check the error codes you need a paper clip. There is a diagnostic connector under the dash, somewhere near the steering column. The connector is two rows and about 10 pins long. In one corner of this connector there are two pins next to each other . Most of the connector is empty. With the key in the off position, bend open the paper clip and plug it in to short these two terminals together. then turn the iginition key ON but do not start the engine. the check engine light will begin to flash. It will first flash a code twelve. all of the codes are 2 digits. the light flashes on and off in a pattern to display the codes. IE: a twelve will be: flash, long pause, flash, short pause, flash, long pause. Each code is repeated 3 times. When it has flashed out all of the stored codes it will flash 12 again. if you have no stored codes it will still flash 12 and repeat infinently. To exit diagnostic mode, turn off the key and remove the paper clip. To clear the codes, after you replace parts or fix the problem, pull the ECM fuse that is near the auxilary positive battery terminal. Wait about 30 seconds and plug back in. If you have any problems or the connector looks different let me know. Good luck CLEAN THE INTAKE Quote Link to comment Share on other sites More sharing options...
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