91 Lumina stalls- even tried a psychic :-)

[Kooterskkar]

True, but that wouldnt make it stall.

[tmcsherr]

tblake:
OK...we forget ignition....and per previous posts, we can forget O2 sensor also...and the fuel pump has already been replaced...so, it looks like consensus is regulator or TPS as the two most likely places to start.

jeremy:
if timing stays in module mode...should still be able to accellerate, just not good, right. But the problem is that you cant accellerate...any attempt to do so stalls the engine.

jeffco:
your maintenance routine sounds like a good regimine to follow...300K miles...I'm impressed!

[DLHUTCHENS]

The Stalling Is Caused By One Or More Fuel Injector's Spraying Too Much Fuel In The Cylinder. The Computer Tells Each Injector When To Spray And For How Long. When The Computer Starts To Fail, (this Does Happen) It Will Tell An Injector To Stay Open For The Wrong Amount Of Time. Usually Too Long Which Sprays To Much Fuel For The Plug To Ignite. So No Power Stroke And The Engine Stumbles And Dies. But The Car Will Start Right Back Up And Idle. It Just Dies When You Step On The Gas While In Gear. So It's Very Confusing And Hard To Diagnose. Don't Waste Your Time And Money On Sensors Or Ingnition Parts Until You Replace The Computer. You'll Just Be Stuck Scratching Your Head Or Kicking The Car. Yes The Computer Is The Expensive Part. But If It's Shot, Nothing Else You Do Will Produce Results.

[tmcsherr]

"But The Car Will Start Right Back Up And Idle. It Just Dies When You Step On The Gas While In Gear"

Ok...what about if it's not in gear....will it still stumble if it's a bad computer? It stumbles in neutral also.

[jeffcoslacker]

Originally Posted by tmcsherr

"But The Car Will Start Right Back Up And Idle. It Just Dies When You Step On The Gas While In Gear"

Ok...what about if it's not in gear....will it still stumble if it's a bad computer? It stumbles in neutral also.

Did you do the ohmeter sweep test on the TPS yet?

[Jeremy-WI]

Here's something from another site that may be a possibility: http://www.chevytalk.org/threads/sho...t=1#Post952529

[tmcsherr]

[quote]Did you do the ohmeter sweep test on the TPS yet?[quote]
I've been waiting for the car to act up again...not much point in troubleshooting components when they are acting right....geez...this is the first time I've actually been HOPING for it to cut out....

[cjslumina]

If your car is misfiring from your injectors spraying wrong, wouldn't your computer shoot out a code that would show misfiring? Just asking

[Jeremy-WI]

cjslumina, on a OBD2 vehicle it should kick out a misfire code, but the 91 Lumina is pre-obd2. It may set a rich code eventually.

As intermittant as this problem is, it almost has to be electrical in nature or an electrical component. Checking the battery connections for corrosion would be a good place to start

[jeffcoslacker]

[quote=tmcsherr][quote]Did you do the ohmeter sweep test on the TPS yet?

I've been waiting for the car to act up again...not much point in troubleshooting components when they are acting right....geez...this is the first time I've actually been HOPING for it to cut out....

You may still see minor drop-outs in the reading even when it is working correctly. If so, it's bad anyway. Should have no drop-outs in reading at all. The ECM can ignore minor mometary glitches.

[richtazz]

I hate to beat a dead horse, but you have a bad fuel pressure regulator, period. It's a cheap and easy fix, and will cause all the symptoms you describe. Also, in keep it simple and cheap mode, check the vacuum line that goes to the regulator. If it is cracked or partially disconnected, it would cause the same symptoms as a bad regulator, and would act up intermittently.

[Jen74]

Have you checked the catalatic converter, fuel pump and fuel pump relay? These a few things that I have had to change since my car has had similar probs. As with yours I didn't get any codes either.

[RCSpeed]

If you decide to take off the upper plennum to replace the pressure regulator, check the resistance of the injectors. It should be 12.2 or higher up to about 16 ohms. These short out and can cause the problem your having. At idle, the injector on time is very short and theres not much current demand. When you open the throttle, injectors stay open longer to spray more fuel and they demand more current. This is when the shorted coils show up. When current demand gets too high, the computer has a fail safe built in to protect itself and will shut down causing your dying problem. You can check 2 of the injectors without lifting the plennum. I'm surprised no one else has mentioned injectors since they were a hugh problem in these engines from 88 to 94. GM issued updates of approx. 8 different types to try and solve this problem. They discovered that alcohol based fuels would eat the windings in the injector and make them short out..good luck

[Scott-Ohio]

Originally Posted by RCSpeed

a huge problem in these engines from 88 to 94

I've been reading this post and agree there's a strong chance your injectors may be going bad--the GM Multec injectors used in 2.8L, 3.1L ("T" engine) and others have a historic problem of shorting out and then initially cause erratic performance.

I'm not ruling out the fuel pres reg though, because while you may have good pressure at the rail, you may not have sufficient volume--I believe you should get ~ 1 pt/30 secs, but don't quote me on that!

While the throttle pos sensor could be at the root of your probs and this may be the "cheapest" and "easiest" fix, I'd suggest taking RCSpeed's advice first and check the 2 accessible injectors' resistance value. One is near the oil fill cap and the other is diagonally across from that one. Anything below 10 ohms should be replaced soon!

Rather than waiting for symptoms to return and since it's just a matter of time before your 13+ year old injectors start failing and leave you/your daughter's stranded when it won't start, I'd highly suggest the following $300 investment [presuming, you do the work :-) ]:

- Replace all 6 injectors with reman Bosch units w/lifetime warr ($200)
(see link below for injectors)
- Replace fuel pressure regulator while you're there anyway ($80)
- Replace Crankshaft Position Sensor--critical component! ($17)

When you tilt the 3.1L forward, like you would when you replace those back spark plugs, it's fairly easy to "feel" around for the CPS and replace it, or you may be able to "squeeze through" from below with car on ramps/jacks. Also, the O2 sensor is cheap (~$18) for your car and is easily accessed with engine tilted forward and if you haven't replaced those back 3 plugs yet, this would be a good time to those too @ $1.70 each. Finally, I think you'll find the plenum/EGR/throttle body/etc. easier to remove with engine foward!

Quick comment on the CPS is if it's original, chances are the plastic covering the magnetic is getting brittle and you don't want that thing breaking in the crankcase like mine recently did! Not only did I lose spark on all cylinders when I hit a small bump in the road leaving me stranded, but the little plastic bits are in the crankcase and that's NEVER good!

Here's the link for injectors and good luck! BTW, I'm not affiliated with the company below--someone passed the info on to me and I'm just passing on to others!

http://www.lindertech.com/reconinj.htm
-

[tblake]

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