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Bizarre "almost dying" problems


SmoothSteve3

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Hey everyone-

 

Ok, so I've almost got my '90 lumina 3.1 MPFI working great.....she still is a bit of a hard start, but thats not my main concern right now. Ever since I've had her, there's been this one weird problem....

 

After I start up and shift from either park to reverse, or park to drive, the engine will sometimes die, while other times it just gets REALLY close to dying. The problem is magnified from park to reverse, but still present from park to drive. Here's a list of what I've done recently:

 

Replaced IAC valve

Replaced Crankshaft Position Sensor,

Cleaned Throttle Body

Put in 160 degree thermostat

Replaced Sparkplugs (Rapidfires)

Replaced Sparkplug wires (Stock Delco wires)

 

Could it possibly be the Throttle Position Sensor? Or do you guys think its something else....

 

Thanks!

 

SmoothSteve3

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If you've replaced the IAC and still getting irractic idling issues... it needs a re-learn / re-set.

It's looking for the correct number of "steps" or "counts" so the engine stays running.

Try the re-learn procedure and see where you end up.

 

thanks to redfox for posting that!

 

Hey, just trying to help out anyone / everyone who needs it...

Besides, it's preety muched asked on a daily basis; I don't need to re-type it everyday... :D

 

- Erik

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I've got the same problem -that is with dying and hesitation after replacing timing belt. I tried the idle relearn procedure but it didn't work so i'm going to keep trying. The GM mechanic said that the idle will relearn itself over the course of driving the car, but worried me when he said he was getting random misfires on all cylinders. I put in bosch +2's in about 2 weeks ago and the stock plug wires don't look too bad. Any way, I'm going to put in Delco plugs with magnecore wires which will hopefully take away the misfires. Do you (anyone) think 80,000 mi plug wires and Bosch plugs would cause so many random misfires and an f'ed up idle.

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Futhermore, do you think the GM mechanic was right about the car's computer just relearning itself; this seems kinda wierd.

 

You mean on the idle?

Or are you inferring the car learns the driving style of the driver?

 

- Erik

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Redfox, Do you think Bosch plugs/worn wires could be causing all these misfires?

 

It could. Depending on the gap / age and resistance of wires, that could be an issue.

But, it could be good plugs / wires but a dying Ignition Module / Coil.

 

- Erik

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redfox, how can one check to see if the coils are going bad? If they are gonna go KAPUNK, i will replace them with MSD Coils :-D

 

If it's a definite missfire, check spark on the wires.

A dying / faulty coil will affect a pair of cylinders since there are only three coils.

Otherwise, again, check resistance across the coils. I don't know numbers of that...

Personal experience: had my 2.8L MPFI Celebrity died due to Ignition Module after have mild stalling for about two months.

Sooo... I would double check all things and make sure you're not missing something obvious.

 

- Erik

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