4.3 vortec running rough when cold

[Tyler55]

So im driving a 1994 cheyenne 4.3 vortec. It has a little over 200 thousand miles on it. Tbi. When i start it up it runs good for a minute or two. But it has started to try to die after these two mins. If it is sitting at idle then it will die. After it warms up it drives fine and idles great. Ive completed a tune up. Have replaced my iac sensor, pcv , and im still having issues. Any ideas would be great thanks

 

[df2x4]

So... Is it the original engine to the truck? Because if so it's a TBI, not a Vortec. The Vortec engines started in '96. Just trying to clarify since you said it was both.

 

[Tyler55]

It says vortec on the engine. I though tbi ment throttle body injection my bad

 

[df2x4]

That is what TBI means. The pre-'96 trucks have a pair of injectors in the throttle body, hence TBI. The post-'96 trucks with the Vortec engines used a CSFI spider with injectors for each cylinder. The fact that you're seeing the word "Vortec" in your engine bay tells me someone may have swapped a newer engine into your truck. Can you post a picture?

 

[DerekTheGreat]

Pardon my ignorance here but I thought after 91 or something GM started calling the 4.3 "Vortec" for S&G's? Technically it was still TBI but GM nomenclature called it a Vortec... Thought I read that somewhere. Anyway, I cant imagine someone went through all the trouble to swap an actual Vortec V6 in...

Back to the OP's question: Have you tried swapping in a known 'good' engine temp sensor?

 

[c1500deathtrap]

The Vortec nomenclature started in the mid 80's on the v6 engine. Because the new swirl port heads made a "vortex" in the combustion chamber.

 

[df2x4]

Huh, well I learned something today about the Vortec nomenclature in relation to the V6. Still curious about where that would be displayed in the engine bay of a '94 V6 truck, though. The first thing that comes to mind for me is the resonator box on the Vortec intakes.

I agree with @DerekTheGreat's suggestion about the coolant temp sensor. Also could be ignition related.

 

[Tyler55]

Says it right on the valve cover. It does have the two ingectors as well

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[Tyler55]

And i have not tried the temp sensor i could see that being an issue. Something i forgot to mention in the initial post is that it was running good until i put an engine cleaner into it. Thoughts on that ?

 

[joep88cheyenne]

You might want to change your fuel filter. It sounds like a symptom that could cause this. I have seen this in other cars.