It's my nephew's 1992 Chevy Astro. It has a 4.3l V-6. You start the thing up and it runs fine when it's cold. Once it warms up, it doesn't want to run any more. It won't idle and will only run if it is in park and someone is revving it at least 1500 rpm. Put it in drive and it dies. Anybody have any idea what it could be? Seems like it would have to be a fuel system or throttle body problem. Also, you don't get an SES light or any other idiot light.

Anybody have something that pulls codes that I could borrow? Even without an SES light I'm thinking it might be throwing some codes.

 

Could be something simple like a disconnected vacuum hose.

 

egr will cause a major vacuum leak when they fail.
They also have heavy carbon deposits build up on the pintale and it cause's a vac leak...stalling, nopower, etc.

 

this is a good idea to check, but he said it runs fine when cold. usually if its a egr probleml, its always there. it has a maf sensor right? if so, try disconnecting the connector and see if that has an effect on it. if thats the problem, it should straighten out and run good. Id take out the o2 sensors also and see what condition they are in. if they are coated (white or heavy black soot) then its possible they are sending the wrong signal. ie.. telling the pcm its rich when its really lean. you need a scanner to read the data list and see what the inj. pulse width and longterm rates are at so you can tell if its adding fuel, or taking it out. also take a look at the idle air speed is. if its 0, then theres a vacuum leak. its very possible that there is a vacuum leak only when its warmed up and as the metal expands, exposes the leak. but when its cold, seals up. you could also take a look a couple plugs too, so see if they are rich or lean looking.

good luck
chris

 

My money's on the EGR. I had a 93 S10 Blazer and it happened twice. Both times it was after it had been run on the highway so it was warmed up. Come to a stop sign and it sputtered and stalled.
Replaced the egr and it fixed it. I was told it was pretty common for carbon to build up there and cause it to hang open.

Bob

 

Scott,
I can scan it for ya if you need it. I think i know what it is. Does it have a 700R4 trans? If so unplug the TC lock up selinoid(sp) then start it up and put it in drive ....you might have to do that till it unlocks then it should run fine. Any ?'s or need help call me @ 313-607-6637. Steven

 

IT SOUND'S LIKE IT IS THE COLLENT SENDING UNIT FOR THE ECM.
IT MIGHT BE UNPLUGED, OR BAD. IT WILL RUN GOOD WHEN IT IS COULD, BUT RUN LIKE SH*T WHEN IT WORMS UP. ONE SINE OF THIS IS RUNNING RICH.

 

Thats what I said over in the MM post. So many opinions... poor guys going in circles

 

Thanks for all the suggestions! At least now I know all the typical problems to investigate first. For my broke nephews sake, I hope it turns out to be something cheap and easy to fix.

 

Keep us posted. Thanks Steven

 

*back from the dead*

My 94 Bravada needs a new EGR valve - and I honestly havent done too much to it, nor looked hard at the 4.3L CPI Vortec...

A garage wanted $627 to replace the EGR valve, Plenium gasket, and do a fuel system cleaning... ditch the cleaning, and we're still talking $550+...

I looked up at Napa and I can get the EGR valve for $45 and the gaskets for under $15. How hard is it to replace the EGR valve on these buggers? Any tips/advice? I know on the lt1 it's easy... does this follow suit?

 

It is easier! The 4.3 vortec it should be right in front. 5 minute job. Steven

 

maybe 10 minutes, depends how long it takes to find a 10mm socket and an extension

 

On my nephew's van, it was on the back of the motor. Very easy to access once the cover was off. Hell, it took us longer to get the cover under the dash board off then it did to pull the EGR valve.

In his case, it turned out someone that was unhappy with him put sugar in his gas tank. Fresh gas and fuel pump and he was all set (until he rolled it a couple weeks ago).