Help Idle Issue.

[floyd25]

Hi,
I have an issue with my 93 explorer. When I start it up it wants to Idle high around 1500 rpms. I've checked the TPS and that's fine. I checked the codes and it came up with 5 of them. All came up during KOER test.

code 412, Can not control RPMs during KOER, high RPM check.

code 538, Invalid cylinder balance test due to throttle movement during test.

code 536, Brake on/off (BOO) circuit not activated during KOER.

code 116, Engine coolant temp. higher or lower then expected.

Cyl: 6, cylinder number.

If anyone can help me resolve any of this issue, it would be much appreciated.

 

[MrShorty]

Can I assume it passed (111) the KOEO and CM portions?

KOER 116 is often because the engine isn't at operating temperature during the KOER test. If you are certain it was fully warmed up, then check the ECT sensor output to see if it's reasonable. I've seen tables of resistance vs. temperature in Chiltons and in this forum.

KOER 536 almost always means that you neglected to press on the brake after engine id was output. Review test instructions and repeat test.

I'm not sure where you got your code description for KOER 538. KOER 538 almost always means that you neglected the "goose" test portion of the KOER test. As with the previous code, review test instructions and repeat test. If your instructions don't mention these steps in the test, try reviewing my notes on pulling EEC-IV codes thread in the EEC-IV forum and the other instructional threads we have here.

KOER 412, in the absence of other codes, is usually not a very useful code. It simply means that the computer couldn't control the engine speed correctly during the KOER test, because the engine is idling too high (which you already knew). If I assume the other three codes "clear" up by repeating the test correctly, then I would start by checking for vacuum leaks (a vacuum leak will cause a high idle).

 

[floyd25]

Thanks for the help, I will rerun the test when I get off work.