93 Explorer "check engine" codes

[TheJMan]

My brother's 93 Explorer had the check engine light come on today. I took it to Checker and had it scanned and it gave me the following codes:

136- Something about the system being at the lean limit
238- Electronic Ignition Coil failure

If the engine is turned off and then turned back on, it will run fine for a few moments, and then starts idling erratically and the check engine light will illuminate. It bogs badly when accelerating at around 1200 RPMs, and then surges. It also sounds like there is a fast tapping noise coming from the engine at higher RPMs.

Also of note: this car was in a shop today and had the A/C compressor replaced.

Has anyone had any of these codes before and if so, how did you fix them?

 

[MrShorty]

Brooklynbay has posted a decent list of code definitions in the EEC-IV forum. You might review that for code definitions. My notes on pulling EEC-IV codes has some useful information to help get the most out of the self-tests.

SOP when diagnosing these is to start by resolving KOEO codes. Did you get a pass 111 from the KOEO codes? Once KOEO codes are resolved, then work on KOER codes. My code list suggests that a 136 can only be a KOER code, so that would be the place to start. Note that there is more to an O2 sensor code than replacing an O2 sensor. Incorrect fuel pressure, misfires (possible link to the CM 238 code???? The "fast tapping noise" isn't spark leak from the coil/wires/plugs, usually pretty easy to see in the dark?), exhaust leaks, vacuum leaks, bad wiring, and so forth and so on can all contribute/cause O2 sensor codes.

 

[TheJMan]

Well, I checked the MAF and it was really nasty looking, so I cleaned it and it still didn't help any. Replaced the MAF, and all is good again.

 

[BrooklynBay]

Here's a link to my list of 2, and 3 digit EEC-IV codes: http://www.explorerforum.com/forums/showthread.php?t=160035