I just purchased a 1995 S10 Blazer with the Vortec 4.3 V6 the other day. I got it running very poorly back fireing thrugh the exsaust lightly (poping), etc. After reading around the internet I figured it was the Spider (CPI injector). So I took off the upper intake, and found that the Nut kit (the fuel lines running into the injectoer), were leaking badly and dumping fuel into the manifold. OK so I replace the Nut kit, and bit it back together. Now the truck runs great, nice and smooth. However it idles at around 2500-3000 RPM, and will not come down. The previous owner replaced the EGR valve (with a used unit)and the fuel pump. I tryed unplugging the EGR valve, and that did nothing. I double checked my work looking for Vac leaks, and could not find any. Also I think it idled fast before the work as well.
What is my next step??
Well Today I pulled the IAC valve, and shot it with some wd40 to clean and lube it. re-insaled it and the idle slowly cam back down to 1000 RPM. Great I figure the problem is fixed, and I turn off the truck so I can change the oil. Finish that job, and go to re-start the truck and now it will not idle at all. If I put slight pressure on the gas pedal it is OK, but as soon as I lift it stalls gain. Im thinking it is a bad IAC, but its $100 for a new one and that is an expencive shot in the dark…
What do you guy think>?
Try a more thorough cleaning of the IAC and idle passages. Use throttle body cleaner, not WD40. Also check the electrical connector.