350 TBI idle/stumble

[ajs79lincoln]

I have an '88 Chevy K2500 pickup w/a 350 TBI and a problem: It starts up fine, but it idles too high or too low to the point that it wants to die. Also, on take off, it stumbles pretty bad, so that I have to really give juice and it runs fine. Also, when I slow down at a stoplight, just as I approach that 5 mph- 0 mph, it just about dies and at the very last second it kicks back in.

I have checked the error codes. At first, I was getting the code for the MAP sensor, which I changed, but the truck only runs the same. Next, I checked codes again, and now I had an O2 sensor code, which I also changed.

Any ideas how to cure this stumble/near stall condition? Thanks in advance.

[tacoma man.]

i just put a 350 tbi in my camaro and its reving up and down i have been trying to fix it, but no good.

[57ringo]

You might want to check the EGR valve and for vacuum leaks.

[ajs79lincoln]

I checked for vacuum leaks all over the engine and cannot find them (at the base of the throttle body, at the EGR, all over the intake manifold, etc.). I also already tested the EGR valve and it works well.

Any more ideas?

[whitewolf44443]

Originally Posted by 57ringo

You might want to check the EGR valve and for vacuum leaks.

check the air idle solenoid on the TBI. sometimes you can remove them and clean the carbon from them using gum cutter. if this doesnt work, check the knock sensor. if this does not work you might have a internal vacuum leak.

[ajs79lincoln]

Whitewolf, thanks for your reply. I'll try out your suggestion. I do have one question: what is an internal vacuum leak? More specifically, how do I diagnose it if it's internal?

[erich conk]

did you ever figure out what the problem was, have same problem.let me know my email is erichconk@hotmail.com. thank you