Chevrolet Repair Questions? Ask a Mechanic for Answers ASAP
Hello, my name is***** the check engine light on? Does it run rough when going down the highway? Thanks
It sounds like problem with iac wiring or PCM not operating IAC correctly. If OK, check the IAC wiring from the Powertrain Control Module (PCM). Verify there are no shorts or opens. Disconnect the IAC motor. For this specific test, a logic probe works the best. Connect the logic probe from ground to each IAC harness wire one at a time. Check for blinking Red and Green lights at each circuit while manually revving the engine up and down. If the circuits are OK, replace the IAC. If one or more circuits are dead, check the wiring/connections, then replace the PCM. Let me know how it goes or if you have more questions, thanks.
You can but it will not work as well because the blinks happen faster then meter can keep up. Next best option would be to use a LED tesetlight. Let me know how it goes or if you have more questions, thanks.
Replace the iac again with a ac delco brand. Let me know how it goes, thanks.
Then just try a different brand. Based on testing and symptoms it definitely sounds like IAC is the problem. Let me know, thanks.
I agree, maybe try a different parts store. Let me know how it turns out. Thanks.
Not sure. If you send a picture I could tell you for sure.
I'm not sure, we have done just about everything I can think of. I'll open question back up to see if someone else has some new ideas. Thanks.
new expert here
any access to a scan tool to see live computer data ?
if you unplug the EGR valve will it still do this ?
see if it still does this with the EGR unplugged
and i am assuming there are NO codes set in the computer ?
if there are NO vacuum leaks and NO codes set ( not the EGR one it just set ) then this issue with 2 new IAC valves being replaced would really lead up right to the computer being bad
now may i ask does it look like anyone adjusted the throttle screw at all ?
if you look at the throttle on the throttle body there should be a stop that the throttle rests on when at idle is that screw been moved ?
the odds are it has not been moved if you did not touch it
this is the direction i would go next i would remove the upper intake manifold and be sure the lower intake where the injection unit is not filled with fuel and also see if the upper intake gasket is broken ot all between any ports
if a lot of fuel is seen replace the injector and a new upper intake gasket
if no fuel is seen just replace the upper intake gasket
if it still does this the only thing let would be the computer itself
try running it spraying some carb cleaner or listen with a stethoscope to pin point that area
then see if you can have it hooked up to a smoke machine and look for the smoke leaking
that way we can at least vacuum leak as being the issue
not that i am aware of
ok let me know