Diagnostic Game

[AcuraTech]

I already have the car fixed. Done. This is a car that I worked on yesterday. Here's how the game works. I'm gonna start by posting the initial problem and then having people guess on things to start checking. I'll follow up later on with answers.

Car: 94 Chevy Corsica 130k miles
Engine: 3.1 V6
Trans: Auto

Problem: Vehicle towed to shop. While driving engine stalled out after coming to a stop. Would re-start in park but repeatedly stall when put into gear.

Initial diag check: Cold engine, vehicle has been sitting outside for a few days, ambient temp 40 degrees. Engine starts right away but the idle is very high (approx 2500 rpm). White smoke and a rich fuel smell coming from tailpipe. When vehicle is shifted into gear it sputters and stalls within a few seconds. Service engine light is OFF.

So, what do we start checking first?

 

[asiancivicmaniac]

MAF sensor

 

[AcuraTech]

Originally Posted By: asiancivicmaniac
MAF sensor


All voltage input and output checks for MAF check OK, and the element is clean. MAF is OK.

 

[Nyquist]

Don't those have a transmission lock-up that can go bad causing that stalling problem? If that is Ok, I would check fuel pressure. If both those pass, idler motor.

 

[JTK]

Stuck or inop idle air control would be my guess if you can keep it running by feathering the go pedal.

Joel

 

[Spykem4e]

white smoke? If your coolant level is going down, then its the head gasket. Same thing happened with all the description you mentionned on my sunbird 3 times.

If its not the problem, I would say maybe the transmission lock-up? But 2500 rpms at idle is very high... something around the maf...

 

[highe]

02 sensor?

 

[IndyIan]

I'd check for an air leak after the mass air flow sensor first if there is a flexpipe between the sensor and the throttle body.

Like if the air filter box and MAF sensor are mounted on the body of the car with a flex pipe to the engine. A crack in the flex pipe can open and close when the engine torques over when its put in gear.
We had a car that would drive perfectly in reverse but stall out going forward, this was the reason.

 

[yeti]

if the white smoke is thick, probable head gasket. as no codes came up, possible iac, or poor battery.often,if the battery is weak, the main computer is not getting enough power to work properly. this can cause driveability issues. good luck.

 

[Quest]

multiple issues most likely, but will definitely first check all the computer related sensors in cold start mode: incl. but not limited to just temp sensor, air temp sensor, MAF sensor, throttle position sensor, air leaks on the intake side.

Then check and replace thermostat if it deemed necessary.

Warm up the car and then check to see if it still comes to a stall (engine warm) when shift to D.

After checking for CEL codes (OBD-I type), then go back and focus on cold stall on engine. Granted that the engine sensors/temperature problem resolved, and if that symptom of stalling goes away, the problem is probably solve. If not, check A/T vacuum motor and then try again.


Enlighten me with your next info/step plse.

Q.

 

[swalve]

Timing belt slipped a tooth or two?

 

[brianl703]

A bad/disconnected engine coolant temp sensor will cause it to run rich.

 

[brianl703]

Does this car have a MAP sensor too?

What are the block learn/integrator values?

 

[mechtech2]

Tough to tell.
Could be a bad head gasket with concurrent cat converter flow problems.
Yank the plugs and look for a clean or wet one, and take a compression check.
Also a pressure test of the cooling system.

 

[The_Jeff]

It's the classic 3T40 torque convertor clutch issue. Probably was flooded by all the ruckus.

 

[brianl703]

This does sound like there's more than one problem.

 

[alanu]

who cares its fixed

 

[tom slick]

bad brake booster

 

[drivewaytech]

I'm leaning towards bad brake booster, causing a large vacuum leak.

 

[The_Jeff]

^ I actually kind of like that idea, one needs to hold the service brake to keep it from taking off in drive. Maybe a ruptured diaphragm that's only trouble when it moves.