bryandj23 Posted May 31, 2005 Report Share Posted May 31, 2005 Just wondering if anyone has experienced this. Got a 1992 Grand Prix with the 3.1 MFI (not 3100) engine. Driving down the road, everything seems fine, until a sudden (very quick) loss of power is noticed. Then, once your foot comes off the gas, the car stalls. Getting the car running again is sometimes a chore - even to the point of having to hold the pedal to the floor to get it firing (although sometimes it barely runs with the pedal to the floor - releasing the pedal stalls the engine). The car the runs VERY rough, sputtering black smoke out the exhaust. Very Low acceleration. After driving awhile, or letting it sit - you can start it back up and everything seems OK once again. During the time that the car is in it's "Pissy mode", if you get the chance to rev the engine really good, you can see carbon shoot out from the area of the intake where the EGR (electronic EGR) is installed. At first this only seemed to happen when fuel was lower than 1/4 tank. This past weekend completely tossed that idea out the window when after topping off the tank, and driving about 10 minutes, it started PMS'ing again. I haven't scanned for codes yet, because I figured that the only one I would get is O2 sensor detects "rich mixture". Duh. I'm leaning more towards Fuel Pressure Regulator (don't know if this model has one), coil pack slowly on the fritz, or MAP sensor? From what I can tell, either the engine is getting the fuel slammed to it, or 2 cylinders are going down, which would make the engine act like it's flooding. Thoughts? Quote Link to comment Share on other sites More sharing options...
Brian P Posted May 31, 2005 Report Share Posted May 31, 2005 Maybe the EGR is faulty and opening up, letting in way too much exhaust in? you mentioned seeing smoke near the EGR valve. I had a problem with my old car's electronic EGR that was stuck open, however it ran bad ALL the time. There is a vacuum controlled fuel pressure regulator on the fuel rail, adjacent to the throttle body if you want to check that out. Quote Link to comment Share on other sites More sharing options...
bryandj23 Posted May 31, 2005 Author Report Share Posted May 31, 2005 Yep - there's definately smoke(?) or carbon(?) coming from the EGR valve - but only when it's running (or lack there of) shitty and you actually manage to rev it up and get some RPM's out of it. Is there a quick fix for a stuck EGR, or should it just be replaced? Fuel Pressure Regulator: Ok, so let's say the car's having a moment and I can get at the regulator - is there a way to test it? Quote Link to comment Share on other sites More sharing options...
Brian P Posted May 31, 2005 Report Share Posted May 31, 2005 Just replace the EGR. They go cheap on ebay or the junkyard. Almost any GM EGR is good from 1990-1995 for you, just be sure it's the same 3-solenoid digital type. Usually a bad regulator will leak fuel out of the vacuum port. Quote Link to comment Share on other sites More sharing options...
bryandj23 Posted May 31, 2005 Author Report Share Posted May 31, 2005 Cool. Maybe I'll just take the one out of my 91 GTP, since that car is just sitting at the moment. If that's the culprit, then the GTP will get a new one. I'll post what happens - thanks for the info! Quote Link to comment Share on other sites More sharing options...
bryandj23 Posted May 31, 2005 Author Report Share Posted May 31, 2005 One more quick thing - should I NOT rule out coils? Does this seem like the symptoms of a possible coil or ICM going bad? Quote Link to comment Share on other sites More sharing options...
bryandj23 Posted June 1, 2005 Author Report Share Posted June 1, 2005 Ok. Let me bring you all up to speed a bit. This is my g/f's car. Her dad (who thinks he's the best mechanic), is thinking of replaceing the O2 sensor, and he sorta agreed with me about the EGR valve. His solution was to simply unplug the EGR valve and see if this situation happens again. Since the car was running fine at the time, and if my thinking is correctly, the EGR valve couldn't possibly get "stuck open" if the electrical was disconnected from it. Am I thinking right on that? Well, guess what - my g/f just called me on her way out of town, and the car's doing it again. Black carbon comes out of the EGR valve, sputters, no acceleration, etc. Could a coil be the culprit? Quote Link to comment Share on other sites More sharing options...
GP1138 Posted June 1, 2005 Report Share Posted June 1, 2005 Ok, do me a favor. It sounds to me like your EGR passages are clogged up with carbon. Take off your EGR valve and start your engine, rev it a few times. Keep your head clear, as carbon could fly out of the passages. If you really want to clean them out good, get some speedometer cable, fray the end of it, and stick the other end into a power drill, and stick it in there and just spin the drill. Move the cable in and out and that should give the passages a good cleaning. Clogged EGR passages could definitely cause it to run shitty. Edit: If the FPR is bad, gas will come out of it when you remove the vacuum line. Quote Link to comment Share on other sites More sharing options...
bryandj23 Posted June 1, 2005 Author Report Share Posted June 1, 2005 That's what I'm gonna do as soon as I'm out of work. I couldn't agree with you more on this. I'm also gonna scan the computer - see what comes up. I'll post back what I find out. Thank you all again. I very much appreciate it! Quote Link to comment Share on other sites More sharing options...
bryandj23 Posted June 1, 2005 Author Report Share Posted June 1, 2005 Ok...got the EGR out - gonna run and get a new gasket and some carb cleaner. Damn - quite dirty. I took the EGR apart down to the pieces, cuz it seems like carbon was even inside the solenoid chambers. Scanned the computer, here's what I got: 15 - Coolant Temp Low 23 - IAT/MAT Temp Low 43 - Knock Sensor (Duh) 53 - Overvoltage I read somewhere that if you get a 53, it's most likely the ECM due to a capacitor design flaw in the power circuit on the ECM. I read this on a Lumina board while doing some searching. Can anyone verify this? Quote Link to comment Share on other sites More sharing options...
Brian P Posted June 2, 2005 Report Share Posted June 2, 2005 If you get a lot of codes like that, PLUS code 53 I'd say it could very well be the ECM. Actually when I had an ECM go bad, I had a code 43 that I could NOT get rid of, after I replaced the knock sensor, plug, AND wire! Quote Link to comment Share on other sites More sharing options...
bryandj23 Posted June 2, 2005 Author Report Share Posted June 2, 2005 Since my girlfriend just recently acquired the car, I figured I'd clear the codes out, just in case those could have been from something along time ago. Apparently the engine had been replaced in that car. Replaced the EGR, and did an idle relearn...Twice. Still idles a bit low, especially put in gear - sounds like it wants to stall. I increased the idle a bit on the TB just for now - the catalytic converter sounds as if it's probably close to shot because of the engine problems. The EGR was PACKED!!!! If it happens again and the 53 code comes up - guess we're lookin at the ECM. Keep ya posted. Quote Link to comment Share on other sites More sharing options...
GP1138 Posted June 2, 2005 Report Share Posted June 2, 2005 Well, even if it's not the EGR, at least you cleaned it up and you won't have to worry about it. Quote Link to comment Share on other sites More sharing options...
bryandj23 Posted June 6, 2005 Author Report Share Posted June 6, 2005 Despite a clean EGR valve, this POS still wants to act up. Checked the codes, and I get a 42 and a 53. Looks like I'll be replacing the ECM. Here's my next question: I've got a buddy whose family owns a junkyard. I should be able to get an ECM for nothing. Now, is it safe to look for a 1993 3.1L vehicle and that's it? Or should I be matching up part numbers, etc? If these ECM's have a history of being bad - should I keep a couple stocked in the basement? Quote Link to comment Share on other sites More sharing options...
Vegeta Posted June 6, 2005 Report Share Posted June 6, 2005 They dont have a history of being bad. You can use a 91-93 DOHC computer or a 93 w body 3.1 computer. You need it to have the extra ram on board to control the 4T60-E. The number on the ECM will end in 9396. Quote Link to comment Share on other sites More sharing options...
Redwingvksm Posted June 8, 2005 Report Share Posted June 8, 2005 ... Scanned the computer, here's what I got: 15 - Coolant Temp Low 23 - IAT/MAT Temp Low 43 - Knock Sensor (Duh) 53 - Overvoltage ... Did no one notice the first 2 codes? If you can start the car w/ the pedal to the floor - your engine is flooding. When you hold it to the floor when starting - it shuts off the injectors. Your computer is seeing that the outside temp is -40*F and is throwing tons of fuel to compinsate for that extra air (due to it being colder/denser) so replace the Coolant Temp and Intake Air Tempature (IAT) sensor and you should be 100% good to go... Comon guys - just put 1 and 1 togther... Quote Link to comment Share on other sites More sharing options...
Brian P Posted June 8, 2005 Report Share Posted June 8, 2005 not necessarily. Could it be a coincidence that BOTH sensors that the ECM uses to read temperatures went bad? maybe, but also that could not be the problem. Pre-OBD2 computers are more susceptable to showing codes unrelated to the actual problem. Also, I believe having the IAT sensor unplugged shows the computer it's -40* out as well. If that's the case, I've started these engines many of times with that sensor mistakenly unplugged. Never had an issue like FLOODING. Quote Link to comment Share on other sites More sharing options...
Redwingvksm Posted June 8, 2005 Report Share Posted June 8, 2005 IAT is smaller compared to Coolant temp. Go outside and unplug BOTH. $20 says your car will run just like his... Hell - test the 2 sensors and see if they are in the spec to make sure. Get an Ohm reader and make sure I'm 100% right... Quote Link to comment Share on other sites More sharing options...
Brian P Posted June 9, 2005 Report Share Posted June 9, 2005 IAT is smaller compared to Coolant temp. Go outside and unplug BOTH. $20 says your car will run just like his... Hell - test the 2 sensors and see if they are in the spec to make sure. Get an Ohm reader and make sure I'm 100% right... $20 you say? But it's probably not even fair. I have a different ECM. Quote Link to comment Share on other sites More sharing options...
wally05 Posted June 9, 2005 Report Share Posted June 9, 2005 My old sunbird did the exact same thing and we did everything you checked (egr, fuel psi, etc), but I ended up having to replace the ecm, then it ran fine until i sold it. The ecm was causing it to flood really bad. I can almost gaurantee that it is just the ecm. Hell, my local gm dealership couldnt even figure it out, I had to replace the ecm myself. Korey Quote Link to comment Share on other sites More sharing options...
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