I'm new to this forum, don't claim to be a motorhead in any way. I'm looking for some expert advice on my 92 blazer with a 4.3 non vortec engine. It's carbureted, it has a rough start, and idles really low when cold (stalls if its in drive and I come to a full stop). As I get going it hesitates and bucks slightly but by the time I get up to highway speed its no where near as bad. My father in law and I have been messing with it all weekend, spraying methanol around trying to find an air leak and we've narrowed it down to this part (chrome cylindrical piece below). We can't figure out what it is. We're hoping that if it's some bs emissions part we can trash it and plug the hole. Suggestions? Thanks.

 

That part would be your EGR valve (Exhaust gas recirculatioin) my friend. And that is not a carb'd engine, you have the TBI (Throttle body injection) or "Z" engine as we call it around here. The 8th digit in your VIN is a Z too.

And I would not trash it and plug the hole. Your engine uses egr to keep cylinder temps down, it adds some exhaust gas back into the intake and it gets sucked in the combustion chambers again, it lowers emission levels and all that jazz, as well as prolongs the life of your engine by keeping the temps in check when the engine is loaded up. Its vacuum operated, so you should remove it and see if you can make it move manualy with your lips and a peice of hose, and do a little cleaning in there. Maybe its got some crap keeping it from closing all the way, giving you some egr when you should have none and making for the rough running. Its a fairly cheap part if you rule it as failling your tests, but the cleaning usualy does the trick if its moving when you apply vacuum. See that when you have it off you can move it all the way in and out without it binding up or sticking on you. If it does that then you may just want to replace it with one from the parts store, its not that expensive.

You could also be showing a fault code from it, I dont know if the vacuum ones register an EGR code like the electronic ones on the W engines do. If you are showing an engine light on your dash, you can check it with the "paperclip method" just do a forum search.

 

Alright thanks. Thats what I joined for, haha. I just realized it said TBI on the intake. Duh.

 

So EGR *does* keep temperatures down. That's funny, because I've been trying to troubleshoot my slightly hotter than normal engine, and the EGR hose is disconnected from the intake on my '89. *runs to autozone*