Well for starters I put this 4.3 in another vehicle and it ran ok for a while with the exception of right when I started it, it would run for about 3 seconds and then die. If I kept on the rpms around 2k for about a min it would idle fine and be good till next day. It also had a major sucking sound from the intake during the minute at around 2k then once it idled good the sound went away. I was told to clean the IAC which I did to no avil. I was then told about the EGR and one thing is that I dont have it connected. When doing the eng swap, we 'deleted' the EGR connector from the comp. But for about 200 miles it would run fine with the exception of the first minute at start up. I ohmed the IAC and im reading 50-60 on both A and B, and C and D connectors. I take the IAC out of its housing and turn the key and I can see it moving back and forth. I also have the pintle set under 1 1/8". Then I started it and kept the rpms up again but then would auto accelerate to around 4 and not come back down. The throttle linkage isnt binding or anything. And this was after I replaced the TPS weeks prior. Now I start it and it idles for 3 seconds again then dies, has the sucking sound, but now it wont go to a nice idle after I play with the rpms for a min. It wont idle at all. When I run the throttle around its pretty smooth thru the range. It also burns the **** out of my eyes with the exhaust in the garage. Rich and crap i assume. Any help would be awesome.

 

Sounds to me like a fuel pressure test is in order........I'm gonna say that this is a fuel related problem, hence the running rich condition........

 

I dont see how fuel pressure could be causing all the issues that I have. The richness yes but that could also be because of incorrect air or some crap so the computer is over compensating. I know some about basic eng **** but not about what a possible culprate of all the issues. I will check the fuel pressure though. Hopefully that gets me started. thanks

 

U ever read up on the fuel system diagnosis? do a search, u said u replaced the motor? do u have the upgraded spider assy? I can see how the fuel pressure can and will cause these idle issues u have the fuel pressure test will lead u in the right direction.....

 

:icon_ doh:No, I put the motor from a 95 blazer into another vehicle. I did the pressure test and ign on, eng off, reading 60psi and slowly dropped to about 55. Eng on, around 60 again. I believe that is what its supposed to be. Im going to take the upper plenum off and check for washing or leaking crap. But why would it not idle? It runs great if I hold the throttle to 1k and thru its range. My guess would be that the EGR isnt plugged into the comp and its allowing all the gas to go thru. But I was just asking if it may be anything else:ic on_hyper: