91 Lumina stalls- even tried a psychic :-)

[tmcsherr]

Yup...she was a waitress I ran into...heck, I figured it couldn't hurt...I've tried everything else.

91 Lumina, 3.1., only 41K true miles. Anyway, the problem is that intermittantly, while driving, the engine will cut out and sputter to a halt can happen while stopped at a light or while driving down the road, doesn't matter...when it happens it happens. And, when it happens, the engine will restart and idle fine, but will not accellerate without stalling and dying. The problem usually happens as it's being driven, so the engine is warm...but cooling off doesn't help the situation...sometimes it's undrivable for days....sometimes it will go again as soon as it's restarted. Then magically, it works till the next time.

Once it happens, as I said, you can start the car and it idles fine (while the engine is warm OR after it has cooled off)...you can even feather the pedal ever so slightly and get the RPM's up...but give it a little more gas than that light touch and it just wants to chug and die.

The car was fine (it was a neighbors car), but it had been sitting for 6-7 months when I bought it, and I believe that might have something to do with it???

Fuel filter and pump have been replaced. New spark plug wires and plugs. Even when it's chugging, it seems to be getting PLENTY of spark and fuel. I think it will backfire a little every once in a while when revved. Have put some injector cleaner in the gas tank and have also sprayed some into the air intake repeatedly. The beast is in one of it's "working spells" right now, but I am waiting for it to die again so I can troubleshoot some more.

It's my daughter's car and I don't want her stranded somewhere...gotta get this thing fixed.

I'm not a mechanic, but I've looked thru all the posts...Don't think it's a vacuum leak becasue it doesn't happen all the time. DOnt think it's the TCC because it happens in park and neutral (and besides, I disconnected the solenoid wire and it didn't make a difference). Don't think it's the ECM or EGR becasue, from what I've read, that that stuff doesn't kick in until the engine warms up anyway, and as I said, once it happens, you can go out in the morning to a perfectly cold car and have the same problem....you just have to wait until it decides to go again. Dont think it's a catylitic converter problem, again becasue it is only an intermittant problem and there seems to be a good flow at the exhaust.
(Exhaust is clear...no smoke or anything and doesn't smell rich). There are no problem codes generated.

Again, it always starts...and it always idles nicely as long as you dont give it gas...just cant accelerate.

I don't see any loose wires...the connectors I see are tight. And the ground strap looks clean and tight.

I'm thinking it may be a sensor...if it was the ECM, from what I read, it should at least be drivable, as supposedly when they go bad they default to a limp home mode. Haven't started replacing sensors yet. I'm thinking maybe the MAF might be the one to start with. Any ideas? If you guys think also think it's a sensor, but dont know which one, could you recommend which ones to start replacing in the order of their likely relation to the problem?

Any suggestions? BTW, the psychic said it was a box on the drivers side of the engine compartment....I KNOW you guys can do better than she did!!!

Thanks for any help.

[jeffcoslacker]

Give that MAF a mild beating while idling, as I described on another post, and see what happens to the idle. You might be right. Also, I have seen cars that sat for a long time have mice nesting in the airbox, sometimes they even chew up the air filter, and the MAF gets loaded with debris. Ever look in there?

[jeffcoslacker]

Originally Posted by tmcsherr

Yup...she was a waitress I ran into...heck, I figured it couldn't hurt...I've tried everything else.




Any suggestions? BTW, the psychic said it was a box on the drivers side of the engine compartment....I KNOW you guys can do better than she did!!!

Thanks for any help.

That's funny, 'cause the MAF is "a box on the drivers side of the engine compartment...."

Maybe she's a part time mechanic, and was yankin' your chain...

[jeffcoslacker]

Look at j rickard's post about the '96 Lumina. It sounds like the same symptoms. He's leaning toward a MAF problem too.

[tmcsherr]

Thought about the waitress/box thing, Jeff.....naw...

I read all the similar posts on this and other boards (including jrickards) adn none of them are exactly similar....most complain about bad idle after the stall...mine idles fine...in fact, with rickards post I don't see much similar at all...he got a code for the MAF....I'm not getting ANY codes...his sputters adn stalls adn wont stay running....mine starts right up and idles fine...his check engine light comes on....mine does not....his "smells rich" mine does not etc. etc. etc.

And I found your post on tapping the MAF....did that too....didn't make any difference (in fact, I "tapped" on all the sensors I could reach).

Air filter has been replace....no nesting mice. :-)

Thanks, but any other ideas ?

[tblake]

I had a 1990 lumina 2.5L 4 banger with 190,000 before we got rid of it, and one night at 11pm, coming home from work, just all of a sudden looses power, and eventually dies. I pulled over, started her right back up, and revved it a few times, all was well, revved up, and idled great, till I put a load on it (put it in drive) I could only get my speed up to about 20-30mph, and eventually it would stall again, I drove it home this way, only to pull a code that said a faulty O2 signal. I replaced the O2 sensor, and all was well. Try that. Its in the eshaust manifold right near the front of the engine, or at least mine was, and it has a single wire coming from it. First check to make sure this wire is in good shape, and isnt in contact with anything hot, that can melt the coating, and cause a short. Good luck with everything. Oh, ya, and PS. I doubt very much that tapping on an O2 sensor would cause an engine to run bad, even if the O2 itself was bad. Although this method does work on many sensors.

[richtazz]

you have a bad fuel pressure regulator. Hook a fuel pressure guage to the schrader valve and turn the key on. you should have 31-35psi. Start the engine and it should rise approx 3psi. if it falls, try pinching the fuel return hose, if the pressure rises, the regulator is bad. IF this doesn't work, you may have a bad crank sensor, the windings are failing and breaking up at rpm above idle, but every car I've ever seen with your symptoms is a fuel pressure problem, either due to a bad fuel pump or a bad regulator. Since you say the fuel pump has been replaced, I'd go to the regulator.

[tmcsherr]

tblake: thanks, but your post (as do many others) indicates you got an engine code telling you it was a bad O2 sensor....if mine was bad, I would expect that I would also get that code. I get no codes. Also, your revved up...mine does not...totally different symptoms, but thanks anyway.



richtazz: I will do that and post the results. Actually, that was one of the first things I thought of, but then I started reading all these posts about MAF,MAP, TCC etc...and I didn't see ANY problems that anybody had had with fuel pressure regulator so I let it go by the wayside. Will that test work even though the engine is (for now) running fine? Or do I have to wait till it's screwing up again?

Also if it was teh crank sensor, would it be intermittant? And, wouldn't I get a code?

[Kooterskkar]

How about the TPS. I agree with richtazz that it sounds like a feul pressure problem though.

[richtazz]

yes that test will work even when it's running fine. Pinching the line restricts fuel return to the tank, which will raise fuel pressure, even when the regulator is doing it's job. A crank sensor has windings in it, and when they first start to fail, they can work internmittently, and not trip a code

[jeffcoslacker]

Don't place to much faith in codes, they can be misleading. Or sometimes non-existant. Don't rule something out because no code was set for it. It only sets if the computer correctly percieves the problem coming from the sensor. Have seen 'em set codes for MAF, MAP, O2 sensor all at once, the problem was a clogged catalyst. Gotta think through it.

[j_rickard]

god, I love this website

[tmcsherr]

Thanks guys.
So...it looks like my assignment is to get that fuel regulator tested first of all. If if tests OK, what sensors, in what order would you begin replacing? Crank,O2,MAF? Any others?

Regarding the fuel pressure test, just so I have it clear...if I got normal pressure with key on, start the engine and it rises...it's OK, right? You're saying if it falls, pinch the fuel line and see if the pressure rises, OK, got that. But, if the engine is in it's "good" phase and running normally, isn't the pressure (obviously) going to check out good? And if it rises as it should, what is pinching off teh fuel line to increase the pressure going to tell me? For this reason, wont I have to wait until it's in it's trouble phase and acting up in order to see if the pressure falls? I guess I dont get the logic. (probably a dumb question, but I told you I was no mechanic).

Is there a more reliable test that a properly equipped shop can perform that will diagnose the condition of the fuel regulator even when the car is running properly?

I'm not looking forward to replacing that thing...it looks like removing the intake plenum to get to it is going to be a PITA....looks like everything in teh world is connected to it Any little tricks on the plenum removal I should know about?

Looks like that psychic was psycho...

Thanks for all the advice. You guys are a wealth of knowledge and a great resource!

[tblake]

I dont know how this came up in conversation, but I was just talking with my friend, who is a mechanic, when he just happened to ask if my lumina ever starts hard, I said nope, and he said, that the 3.1's, at least the older ones had many problems with the fuel pressure regulator, and that the part was relatively easy to change, but he said it costed somewhere around 50 bux. He also said that its one of those things that once changed should be good for a lifetime. Just some strange coincidence that it came up in conversation tonight. I just thought I'd share that little knowledge with everyone, and keep everyone else entertained. Good luck, and report back.

[Jeremy-WI]

It could be a bad ignition control module(ICM), but I can't remember how to test it. On the 91's the crankshaft position sensor signal goes through the ICM before it goes to the ECM. The ECM uses the crankshaft signal for ignition timing. You might want to get under the car and find a wire harness that runs from the front side of the motor(ICM to be exact, the coils are mounted to it) under the oil pan and to the crankshaft position sensor to see if the harness is in good shape(not cracked up, worn through or otherwise compromised). You may want to check the other wires at the ICM to make sure they are not backed out of their connectors