4door Intl Posted March 23, 2009 Report Share Posted March 23, 2009 Hi all, I've been meaning to ask about my car's problem for weeks now, and then i came into the Powertrain forum and noticed brohaa's Lumina Euro thread. I read it and i've been experiencing a similar problem for almost two months now. Here goes: I'll come to a traffic light and after five to ten seconds the engine (3.1L) drops to between 4-500 rpm and jumps back up to 8-900rpm, repeating a little slower than counting seconds. It is by no means constant and happens more pronounced on some days than others. Sometimes it will stall out if i leave it, but i'm so used to it now i add my left foot to the brake pedal and apply the gas pedal until it evens out and the light turns green. This really doesn't start occurring until after the engine warms up, and if i return to the car when the engine is still warm it almost always revs to 14-1500 rpm on startup before coming down after five seconds. Other symptoms are stalling when the engine is still cold, again on occasion, and near stalls or stalls when shifting into Park or Reverse. There is a pronounced fuel smell sometimes, but it seems to be more at the rear of the car (where it's been for years as a result of a small leak at the rear fuel tank seam) I rarely fill the tank more than halfway so it never leaks. It did throw code 45 once about a month ago, and 35 (idle more than 300rpm out of range for more than 30 seconds) a few times recently, which sent me to the wreckers to pull an IAC and swap it in on Saturday. Naturally after about a day of being convinced that the replacement fixed the problem it returned again. Fuel economy really does seem to be in the toilet right now, averaging 15L per 100K or about 15mpg 50/50 city/hwy, but no fuel spots on the ground even after allowing it to idle for 10-15 minutes in the same spot. I understand that testing the fuel pressure is simple, but i have no equipment and the thought of paying a mechanic to do it after spending more than a grand on a replacement cradle, exhaust manifold gasket, muffler and O2 sensor installs a few months ago is really unappealing. Especially if it means i have to spend even more on an injector and labour to put it in. Speaking of which, has anyone here ever used a junkyard injector? What kind of cost total am i looking at for diagnosis/replacement it it does turn out to be the culprit? Could it in fact be something else? Thanks for reading. Quote Link to comment Share on other sites More sharing options...
88red4cyl Posted March 24, 2009 Report Share Posted March 24, 2009 This solution probably won't do a thing for your fuel mileage, but I would check out the coils... Last time I had a coil going bad, it would do the stalling when shifting into gear and the idle going down at lights just the same as yours is... After a lot of trouble shooting, I eventually narrowed it down to a faulty coil... I replaced the coil, and all those problems went away... Quote Link to comment Share on other sites More sharing options...
slick Posted March 24, 2009 Report Share Posted March 24, 2009 Only does it when warm, or doesn't matter if the engine is warm or cold? Quote Link to comment Share on other sites More sharing options...
ns87 Posted March 24, 2009 Report Share Posted March 24, 2009 Like I mentioned in that other person's post it sounds fuel related. I went through hell with my car (3.1mpfi) a few years ago when no one could figure out what's wrong. I had to replace the injectors. I bought new ones bc I was young and niave, but JY ones are fine as long as they OHM out between 12-14 and don't leak. Be careful with the check engine codes, because I find sometimes when my car is having mechanical problems it likes to throw random codes that don't actually cause said problems. If it was coil or spark related, I've found on this engine it just stutters and cuts out more. Didn't stall for me as much as the fuel injector prob Quote Link to comment Share on other sites More sharing options...
19Cutlass94 Posted March 24, 2009 Report Share Posted March 24, 2009 Im having the same problem with my car. i still dont know what it is. I need to ohm test the injectors still, but i havent pinpointed the problem yet. Quote Link to comment Share on other sites More sharing options...
88red4cyl Posted March 24, 2009 Report Share Posted March 24, 2009 If it was coil or spark related, I've found on this engine it just stutters and cuts out more. Didn't stall for me as much as the fuel injector prob That could be on this motor.. Mine was a 2.5 4Tech in my Fiero, so the coils may cause different symptoms than in the 3.1... And Chris, from what I understood, he is having the issues when the motor is both hot and cold... Quote Link to comment Share on other sites More sharing options...
slick Posted March 24, 2009 Report Share Posted March 24, 2009 And Chris, from what I understood, he is having the issues when the motor is both hot and cold... Ok, so it doesn't completely rule out the ICM/Coils, but if it happens when it is cold, then it rules out that fact that they are not getting heat soaked. I'm gonna say something with the ignition as well. Your probably smelling fuel because: a) you have a leak, or your not burning all of the fuel in the combustion chamber. Maybe your FPR is bad and dumping fuel, injectors could be bad and pouring fuel, or you could have an external leak, which would not be noticeable, since it would evaporate from the heat of the engine. External or internal leak, it would account for the strong fuel odor you smell. You really need to Ohm out the injectors, and test fuel pressure at the fuel rail, with the car running and with the car off, ignition in the on position. Quote Link to comment Share on other sites More sharing options...
19Cutlass94 Posted March 24, 2009 Report Share Posted March 24, 2009 Ive done everything but ohm test the injectors and test the fuel pressure. every time i have my scan tool hooked up, it wont do it. Everytime im randomly out driving, it does it. bastard doesnt want me to find it! Quote Link to comment Share on other sites More sharing options...
4door Intl Posted March 24, 2009 Author Report Share Posted March 24, 2009 Heck, i forgot to include that i replaced the coils and ignition module back in November. I had only a few weeks of trouble-free driving before this other problem cropped up... Quote Link to comment Share on other sites More sharing options...
88red4cyl Posted March 24, 2009 Report Share Posted March 24, 2009 Heck, i forgot to include that i replaced the coils and ignition module back in November. I had only a few weeks of trouble-free driving before this other problem cropped up... With new or old (junkyard) coils? Quote Link to comment Share on other sites More sharing options...
pontiacmaniac94 Posted March 25, 2009 Report Share Posted March 25, 2009 can you check the fuel pump?? kinda sounds like you are not gettin enough fuel. Quote Link to comment Share on other sites More sharing options...
4door Intl Posted March 25, 2009 Author Report Share Posted March 25, 2009 @88red4cyl : Wreckers parts, but this is a whole different problem than that. With the shot ICM eventually i couldn't drive the car more than a hundred feet without violent stalling fits. Now, the problem doesn't get worse as i drive and is not constant... @pontiacmaniac94: Maybe, i should've included that when the revs go screwy the quiet howl (it has done that for years) from the fuel pump goes right in unison with it. I figured it was just reacting to the lower fuel needs of the engine when its revs dipped instead of perhaps causing it. But, i've had a fuel pump go before and it was shot right away, not months of intermittent failing symptoms. Also, the jumping to 14-1500 rpm on warm engine startup for a few seconds must be a clue, i just wish i knew to what! Quote Link to comment Share on other sites More sharing options...
88red4cyl Posted March 25, 2009 Report Share Posted March 25, 2009 @88red4cyl : Wreckers parts, but this is a whole different problem than that. With the shot ICM eventually i couldn't drive the car more than a hundred feet without violent stalling fits. Now, the problem doesn't get worse as i drive and is not constant... Hm.. When my coil went bad, the only symptom I had when it was cold outside was the car would stall shifting out of park, or taking off from a stop light... When it warmed up (that summer) I had very violent backfiring when the car would get under load, and I would have to hold the accelerator completely to the floor to even keep it running... I also used junkyard coils when I swapped my ICM (also from the junkyard), and the set-up went a whopping two weeks before the problems started from the coil... It eventually led to a complete no start condition, which I was finally able to diagnose... When the coil was replaced, every problem I had been having went away.... This was just my experience though, and it could very well be different from yours... Quote Link to comment Share on other sites More sharing options...
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