hey guys i am having a problem with my 2000 2 door zr2 blazer. i was having a weak in the intake gasket and the i was leaking antifreeze. i was filling it like everyday. it got to the point were i would run hot (very hot) and it started running rough. i got the time to fix the gasket and i figured that i would do a full tune up to help the fix the rough running car. well that didn't work i fixed the leaking gasket but it still runes rough. it only is rough at idle. ti still runes great. i had a friend run the codes on the truck and it came up with a misfire code. looking at the new plugs it looks like the #4 cylinder was running lean. so we figured lets change the spider and see if that work's. well it didn't. the last thing i changed was the map sensor. other then that i am at a loss. i don't know what to look at know. i am hopping some one here will give me a good direction on were to start next. thanks guys.

 

You can unplug the MAF sensor to see if it helps. If it does then it needs cleaned. You can also try cleaning the EGR valve. If none of the above helps the next thing I would do is a fuel pressure and leakdown test followed by a new cap and rotor.

 

i have done everything you said but the leakdown test. that is the only think i dont know how to do.

 

Hook up a fuel pressure gauge to the schrader valve on the ful rail. The key on engine off numbers should be: inital between 60 and 65 and shouldn't leakdown past 55 within 10 minutes. Post back your initial and 10 minutes later numbers.

 

oh OK thats what you call a leak down test. lolol

yes i did that and it is perfect. i tested the fuel pressure and the vac pressure. they are all good.

 

Do you remember what the numbers where? What brand did you use for the tune up? Possible the IAC valve is bad or the TPS. This is a good one, sorry not good for you lol. Hopefully someone else will chime in.

 

it was running steady 60+lb

 

I also have a 00 Blazer with a starting problem. Engine will start, then races, stalls, stammers and races again then it dies. sometimes will idle for a moment or two, then dies. If it's the fuel pump, it wouldn't start at all- my thinking is the tps. Anyone with an answer or similar situation? Thanks