96 GMC with misfire? in cold temps

[ToyCollector]

Hello. I have a 96 GMC 4x4 with the 6 cyl engine. It has about 130k miles and up to a few months ago, ran great.
One morning it was cold out and I started the JIMMY to go to work, it ran fine UNTIL in was to shift from 1st to 2nd gear. In the time during the shift,the engine begins to misfire enough to effect the Tach guage.

So new wires, dist cap, spark coils, no change. Now, when it is warm, the problem never shows up.

I had taken the car to a transmission outfit thinking the tranny was in trouble, but they checked it twice and said it was not the tranny.

I talked to a mechanic who said he had a car that had to have the poppet valves replaced when it was having a similar problem, but that car had the problem ALL THE TIME, not when it is cold out only.

Someone said I may have a bad gas line. Ever hear of a metal gas line getting so porous that it will suck in air when it is cold and seal when the temp gets warmer??? that was the story.

This problem will set the CHECK ENGINE light on if I get on it hard enough but it just says the engine misfired. No help.

Anyone have a similar experience??? I am lost to find a solution.....

Thanks in advance.

TC

 

[lunghd]

Did you see what code it's throwing when the CEL comes on?

I picked up an OBD2 bluetooth code reader that does all kinds of stuff besides just scanning & clearing codes. (Run it with the FREE Android app Torque) You can also look up any codes directly from inside the app! It works great on my son's 1998 Jimmy.

It can track darn near every engine and sensor function on the fly - rpms, air/fuel mix, O2 circuits, etc, etc... and it's CHEAP! (Under $11 at Amazon: OBD2 code reader for use with Android phones )


I don't think this forum gets much use - have you tried BlazerForums?