4.0 rough idle diagnostic help

[JJMaine]

Not sure because but if I remember there is an unorthodox test you can do. Something like start the truck and unplug it while idling and I guess if the idle changes drastically then you know it's working? You'ld have to look it up but it's something like that.

 

[jballard81]

Not sure because but if I remember there is an unorthodox test you can do. Something like start the truck and unplug it while idling and I guess if the idle changes drastically then you know it's working? You'ld have to look it up but it's something like that.

You are correct. If the IAC is working properly and you unplug it at idle your idle should drop some apparently. I will give it a shot tomorrow!

 

[jballard81]

unplugged the IAC while it was idling and the rpm's dropped just a bit. only really noticed it when i plugged it back in and the idle kicked up just a bit. So IAC appears to be good.

 

[jballard81]

@bobbywalter seeing as I didn't finish the leak down test for all cylinders, but the compression numbers are good is it a reasonable assumption to think it could be the injectors?

Or maybe there's a way to test them?

Thanks!

 

[bobbywalter]

hard to say. without testing the injectors.

 

[jballard81]

Snagged the reman Bosch injectors from eBay. Worth a shot seeing as they weren't too bad on the $$.

Give me a chance to inspect the valve covers for leaks as well.