Alright, got a wierd one for ya and need your guy's/gal's help. Here's the lastest update on my bird. Just got it back from a shotp, had a new starter put it. This is the same shop that put a new starter in 3 MONTHS ago!! So I was pissed as it was. Anyway, long story short I get the car back two days ago and its running fine. However he mentioned that my flywheel is missing some teeth...and warned if i planned on keeping the car for a long period of time. But I really don't.

So today I am driving and roll to a stop at a stop sign and the car stalls. I start it back up....roll to a stop at the next stop sign and the car stalls. WTF!!

It won't seen to stall in park, or in D with the E brake on, but once I am moving and slow down it dies!! What do you think this can be? Not the flywheel right?? That's for starting the car no?

Would a bad oil pressure sending you stall a car? Mine was unplugged when I got it back and there was oil the actual electrical connector to the unit. What do you think can be causing this?? Please help, I am looking to trade it in soon and would like to have it in good running shape!! Much appreciated.

 

Ever clean the throttle body (as part of the yearly major tuneup, of course), and did you ever clean the IAC system?

 

the flywheel is used by the starter, and the torque converter (for automatics). missing teeth on a flywheel will not cause the engine to stall. If the throttle body and the IAC are in good working order, you may have another problem... tell me does the car just die, or does it kick a little bit too? When it runs, is there a rough idle to it?

 

My car still has this same problem! I checked for a vacuum leak, I could check a little better but it so cold outside I just gave it a cursory look, anyways my car is doing the same exact thing! Every time I come to a stop the car just starts to die, especially at turns. Maybe it's the IAC, I haven't cleaned it out since I have gotten the car, could be.

 

yea, cleaned the TB this summer. i have never cleaned the IAC though. i actually just read about it last night a few posts down. so i pulled it last night and sprayed it with some cleaner. i haven't taken it for a ride yet and gotten it up to operating temp. i am also going to check fuel pressure tomorrow.

Quick_Trans_Am it just dies out. no bucking or surging of the engine. the rpm's just start to dwindle until it just shuts itself off. as for the idle, its never been as smooth as a kitten (i have had the car for almost 3 years now). but its never been real rough either. sorry if that it too vague. let me know if you need any more info i appreciate it.

 

you need to replace your oil sending switch, i'm not saying that is causing the problem, but its blown thru if you have oil on the connector

i had mine go so bad, that it was literally spitting oil onto the hot exhaust......not cool

 

I could swear that the oil pressure switch had something to do with the fuel pump cutoff as well.... if that's bad, then as you slow down the drop in engine speed and oil pressure could be causing the pump to shut off. Tell me what RPM does the engine idle? my uncle had the exact same problem with his cutlass... I turned the idle adjustment screw up just a little bit, and the car has worked fine since. Maybe you should try that.

 

when the car is first started cold, idle is around 1,000 rpms. once warm and at a stop like i would say it bounces around 600-800 rpms.

 

it does.........but if it shows no oil pressure it supposed to allow NO fuel to engine

not at idle, not at anytime

so that part of the diagnosis didnt fit

his engine starts and idles.........so thats what made me say no

but it should be replaced anyway

 

They probably disconnected the battery to swap the starter. This engine/ECM combination would now require an idle learn procedure done. Else the exact syptoms you describe will occur.

The idle learn procedure was posted within the past week or two.

RBob.

 

idle learn huh? makes since, the battery was disconnected so the ecm reset. but i thought the ecm re-learned automatically. i'll take a look around see if i can find that post.

 

You're right... I couldn't remember how that setup worked. makes sense to me!

 

Actually the oil pressure/fuel pump switch operates in the opposite manner. It is there to turn on the fuel pump whenever there is oil pressure. It is wired in parallel to the fuel pump relay as a backup.

Safety feature in case the ECM dies the fuel pump can still run keeping the engine alive.

RBob.

 

UPDATE:

1) Fuel Pressure checked out. 40 psi in access. & 38 psi running.
2) Removed & Cleaned IAC with throttle body cleaner

my oil pressure sending unit is brand new, put it in about 3 months ago. but since there was oil on the actual connector you think its shot? once its plugged in the guage read the correct pressure. then again, its only 20.00. a new IAC valve is 65.00. plus, i never new the sending unit could cut off fuel. i wonder if it is at all related??

1991teal, do me a favor. lean over you driverside fender and look at your oil filter. now looking at your oil pressure sending unit. from there look up about an inch. is there a hole there. i noticed a hole there yesterday that i can stick my finger into. and there is either water or oil collecting there. i just never noticed it before.

not sure what to do from here, and don't want to take the car out and get stuck....hmmmm. this one's got me stumped.

 

When's the last time you replaced your coil?

 

It can't. The oil pressure switch does not cut off the fuel pump.

It is there to bypass the fuel pump relay to allow the engine to receive fuel if the pump relay or ECM fails.

Again: the oil pressure switch is NOT there to save your engine from loss of oil pressure. It is there to save your hide if the ECM or relay fails at 70 MPH in rush hour traffic.

RBob.

 

ignition coil, i put in my MSD coil about 2 years ago....

 

its a vacum leak the sruging etc is a good tell tale sing of that. check the maf hoses etc for tears or cracks and theck all the other vacum hoses.

 

it not surging though. i have a feeling that its got to be the oil pressure sending unit. i bought a new IAC today...30.00 at Autozone. And also bought a new OPSU, there is definately oil leaking out from where the connector plugs in. i will keep you posted on what happens.

 

check the EGR and associated piping. Could solve the problem. I've heard that it opens when the car slows down, and if it's sticking, it might let too much exhaust gas in at idle and the car will die on you. Worth a shot.

Good luck

 

UPDATE #2:

Ok, so I went out and bought a new IAC valve (27.00 @ Autozone) and another Oil Pressure Sending Unit (20.00 @ Autozone) and put them in. Took the car out for about a 40 mile drive and everything seems to be running A.O.K. I think it was definately the OPSU, thanks for the info on the whole fuel cutoff thing. And I replace the IAC for the f*** of it. So all looks to be good. Thanks for that help :hail: :hail: :hail:

Get this, while i was under the car yesterday trying to fidle with my OPSU, i noticed that the stupid a$$ mechanic never put my fly wheel cover back on!! Grrrrr! I am ripped. Have to call him tomorrow.

Thanks Again!

 

I have a question for you: Do your brakes feel low on pressure or pedal feel funny when you slowly roll forward or backwards WITHOUT hitting the throttle at all then pressing the brakes?- but then feel better when coming to a stop from normal driving speed?

If so then you have a vacuum leak from a line or very possibly it is a slit in the diaphram of your EGR. This will cause the car to die at low speed hitting the brakes., but not in park or drive with the e-brake on like you stated. Just another think to check out to get your car feeling top notch.

 

Good question, and thanks for the heads up! I am at work now, making up time for work missed when the car stalled on Thursday ! But when I get home I will check it out. I am trying not to drive the car until I get my fly wheel cover back.

 

Man.. I hate to be cruel, but it's been said TWICE.... here's the third time. There IS NO Oil Pressure Cutoff Switch! The oil pressure switch is NOT A CUTOFF! It is a BACKUP. The ECU will ALWAYS tell the fuel pump to run if it is recieving info that says the engine is turning... unless that system fails, or the Fuel Pump Relay fails, in which case the oil pressure backup switch keeps the fuel pump running. Ever notice how your fuel pump keeps going for a short while after you turn your car off? That's because the backup is still reading good oil pressure. Need further proof that it's a backup? Read a haynes. Read a helms. Read a chiltons. Read 1000 posts across this board. Need *more* proof? Disconnect your fuel pump relay *entirely*. Car shouldn't start. Right? Wrong. Just let it crank a few extra seconds to build oil pressure, and the bypass will kick the fuel pump on itself. OI! READ!

EDIT-----------
I also see you mentioned gauge pressure. There are, in fact, 2 oil pressure sending units... well, one.

There's the Oil Pressure Sending Unit that sends gauge/idiot light data (note, it is also technically a switch for idiot lights, not a sending unit), and the Oil Pressure Switch that serves as the fuel pump backup. These two systems are completely independant. The ecu actually recieves *no* oil pressure data on third-generation F-bodies. I cannot speak for the OBDII cars, though.. never owned one, don't plan on it.

 

I figured with that rant over with, I should post something useful. With the IAC replaced, the number of things wrong is definitely limited. Cold idle should be higher than 1000, for starters, so we know it's something wrong all-around. The IAC can only compensate so far =\..

A minor vac leak will cause interesting effects.. I had a minor vac leak in my v8 when I bought her, and honestly had no clue till I replaced part of the vac system and she suddenly didn't sound like she had a 230+ @.050 cam in her at idle (damn.. I was so hoping) .. this was with ported vacuum. Not sure on specific effects with leaks at the throttle body.

A major vac leak.. well.. she wouldn't be going anywhere.

Vac leak at the intake manifold, also nasty effects on idle quality.. solution, replace intake gaskets. Not fun. Also consider TB gasket.

EGR stuck open.. Is your car throwing a code 32? (i suppose the question is more "Isn't your car throwing a code 32?" .. damn GM for this note =\ ) ... Never effected mine *that* badly, but, then again, mine could be stuck closed.. I don't really know.. I'm more into the "fabricate a block-off plate and say to hell with the failure-prone V6 EGR system"

Is your car throwing any other codes?

Have you tried a new coil? Ignition module on its last legs? Get a spare spark plug, pull a wire off a plug, ground the plug against a strut tower bolt, start the car, make sure the spark is nice and bright. Yellow is okay. Blue is better. Orange I've always considered very iffy. Note your car will run very poorly during this test.

Checked timing? Timing is good for you =)

Have you replaced every vac line? They probably need it anyway.

Brake booster hose?

I think AGood2.8 was leaning towards the booster hose or the brake booster itself having failed. Good possibilities there as they deal with large amounts of vacuum.

Ked, you wanna get in on this one? I'm sure I've missed a possibility or two

EDIT---------

OI! I really am getting senile. I was thinking about it and just flat forgot to ask.. have you done a compression check lately? The motor could just simply be getting a little too old for its own good. I hate to bring this kinda thing up, but.. yeah.. A vacuum gauge and a compression tester are worthy investments (vac gauge is cheaper, start with that)

 

Jeez! Tech Smurf, thanks for all that info!! Seriously, I enjoyed reading it all. And better late than never. The whole oil pressure and fuel pump relation is really confusing, and sorry if I made it more so. But I think I get it now, and honestly if I do get it...then I am not quite sure if that's what was even making my car stall in the first place. But its nice to see this thread bumped up again, so I can provide a more recent update and keep the conversation going. So here are some answer to your questions.

1) Idle cold IS 1,000 to 1,200 RPMs
2) Idle warm is 600 - 800 RPMs
3) Am I throwing any codes? Nope, none at all.
4) Ignition module/coil? Both are within 2 years old.
5) Spark color? Never looked to see.
6) Vacum lines? Looked them over a couple times and they are all healthy.
7) Brake Booster hose? Connected
8) Timing? Have checked it...forget what it was.
9) Compression checked? Have never done this...bought the car at 70,000....now have 117,000 miles on it. And there has been no noticeable change in its performance till now. That's about all I can add.

I just wanted to answer some of your questions. Since replacing the IAC and the OPSU (by the oil filter) the car hasn't stalled since. Its been a full week now. I am assuming it was the OPSU, since there was oil coming out of the top of it. But since your most recent post I am not so sure that such a problem would have caused the car to stall.

Yes, I did the IAC valvue while I was under there, so I can't point to one or the other. But so far so good, it hasn't stalled since. But honestly, I am nervous everyday that I drive it...I have always had faith in her till recently. This most recent stint that has really erked me. If it warms up tomorrow like it should (39*) I will update you on the timing and spark questions. I am trading it in soon so I need to keep it running and the I don't want to screw the dealer either. Also, I will be driving her for the next couple weeks. If you feel as though there could be something else wrong....feel free to keep this discussion going. I appreciate your guys' help very much.

 

Well, if she's not stalling now, the IAC was getting tired. It happens.. just feel fortunate yours was cheap. Ones in EEC4 Ford EFI systems run about 120 bucks at Autozone.. not the kinda part you want to buy and "hope" it fixes the problem..

 

LOL, go Techsmurf! I should've read all the way down before going on and on about how it's not a fuel cutoff.

If anyone wants further proof... I drove for years with my oil pressure sensor unplugged. You can try it yourselves, if you don't believe me. Go pull the two-wire connector off the oil pressure sensor, and go for a ride. (The one wire sensor is for the gauge. 87-up f-bodies will use a large combination fuel pump/gauge sensor.)

Why'd I do that? Well, when I was wiring my "real" mechanical oil pressure gauge in, I stared and stared at the GM service manual to make sure I removed the correct sensor. (86-below has two sensors, one for gauge, one for fuel pump). So after circling the correct one in my GM book, I promptly went out and removed the wrong one. Was looking at the engine last year and -- hey, what the -- oops. It's back to normal now; just swapped the sensors.

 

Replace your alternator.
From the one with the Frying ICM's by Bad Alternator.
It's sending out a high energy spike to kill the ignition. Sticking on charge, not regulating.
Enjoy the peace.
PS You'll gain back a bit more power after this, too.

 

Gee, its funny you said that!!! My alternator just went on Wednesday. Left me straded in northern CT. Did the replacement in a parking lot. Thankfully I had my tools with me and someone to get me to autozone. That's the most recent update to date.

The alternator I took out had about 35,000 miles on it. As you know I have been running dual underdrive pulley's for about 2.5 years. But I don't think the alt. pulley is to blame. It was a rebuilt altenator with a 1 year warranty...it lasted about 2 years. So it may have just been on its way out. But FYI about the alt pulley.

Let's see, trading the car in in about a week. Only getting 900.00 for it from the dealer and have spend 200.00 in the last two weeks to keep it running. Starter - 80.00, Altenator 80.00, IAC Valve - 27.00, OPSU, 20.00. Its just not fair....LOL!!