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Gary, Chevy Technician
Category: Chevy
Satisfied Customers: 16774
Experience:  15 years GM master tech
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HELP!! I have a 1993 Lumina 3.1, that has an elusive

Customer Question

HELP!! I have a 1993 Lumina 3.1, that has an elusive stalling idling issue. I have replaced many sensors, to include IAC,TPS,MAP,Ignition coil pack assembly (with the control unit under it.) Here's the thing..When the car is cold, it will run and idle fine. After about 20 minutes of driving it, all hell breaks loose. When coming to a stop light, it will chug and idle erratically, then fall on it's face and die. Did find wires to the crank sensor rubbing the oil pan to the point of being bare, so I repaired that. The transmission works fine. I checked for vacuum leaks, none found. Ohmed out injectors, they all show good resistance 13.1 ohms, when warm. I am at my wits end. Can you help?
Submitted: 1 year ago.
Category: Chevy
Customer: replied 1 year ago.
Oh..and no codes from diagnostic test......arrrgh!!
Customer: replied 1 year ago.
Posted by JustAnswer at customer's request) Hello. I would like to request the following Expert Service(s) from you: Live Phone Call. Let me know if you need more information, or send me the service offer(s) so we can proceed.
Expert:  Gary replied 1 year ago.

I am sorry your having this problem

it sounds like you just about replaced everything in this car

when it dies will it start back up like nothing is wrong or you have to wait for it to start back up for a while after it dies ?

Customer: replied 1 year ago.
It will start, but it takes several cranks, and it will idle high, sometimes sputter and die's all over the place...
Expert:  Gary replied 1 year ago.

i am assuming the fuel pressure is good when this happens ?

if so are you 100 % sure those 2 crank sensor wires are good and fixed correctly and in good shape ?

Customer: replied 1 year ago.
Fuel pressure at 35 psi, steady, when fuel pressure regulator unplugged goes up to 45 psi. Those crank sensor wires are fixed correctly.
Expert:  Gary replied 1 year ago.

ok at this point with everything you have replaced this issue with NO codes set usually comes down to one of 2 things

the crank sensor itself or the computer

usually replacing the crank sensor and if it still acts up replace the computer will correct this issue from the sounds of it everything else tests good

Customer: replied 1 year ago.
Gary, why would it fail when warm, and not cold..I thought you got a no start condition when the crank sensor failed?
At one time, someone has replaced the PCM..Can I go to a salvage yard and get one to replace it? Is that an option??
Expert:  Gary replied 1 year ago.

both these crank sensors and computers are temp related to when they act up

i have seen so many of these doing what yours is with either one being bad with no codes

i would lean more towards the computer with the crazy idle and revving when its acting up as that is the only thing thing to can control enough on the engine to do so and yes a crank sensor is more apt to just not have spark but again i have seen them cause these type of issues

yes a junk yard for a computer of the same year and engine size would plug right into this car BUT make sure you swap the chip from the old PCM to the replacement PCM

the issue with these PCM's where internally the glue on the boards inside the PCM was not a good glue and temp will make the internal connections come and go especially when warmer

Customer: replied 1 year ago.
Is the chip swap a difficult thing to do??..i have never done it..
Expert:  Gary replied 1 year ago.

not at all

once the computer is out 2 small bolts will need to be removed to remove the cover to access the chip once the cover is off pop out the old computer chip and pop it into the replacement computer it only goes in one way and you can not mess that up at all

Customer: replied 1 year ago.
I'll try buying a new crank sensor first...then..if that doesn't do it, i'll get a PCM. I shall report
Expert:  Gary replied 1 year ago.

sure thing

you can always get me back for FREE through this post with any follow up anytime even after you rate us here at Justanswer as i do not get credit for my work until you rate us here

Expert:  Gary replied 1 year ago.

how are you making out ?

don't forget to rate us here at Justanswer as i do not get credit for my work until you rate us here

Expert:  Gary replied 1 year ago.

how is the car running ?