124 and 157 OBD1 codes

[mom4teen]

I have a 1994 Explorer, stock. Seems to have all original components because they all have the Ford emblem and stock numbers on them. A year and a half ago, it had the CEL on. Checked codes and they were all indicating a bad EGR. The EGR as fairly new so I checked the EGR control module and vacuum lines. Turned out there was no voltage coming from the PCM so I checked it. It had a broken pin.
I replaced the PCM, no more codes, but the engine idles between 450 and 500 and sometimes doesn't want to stay running.
Is there a way I can fix this idle problem?

 

[FR-425]

If you currently have codes 124 and 157;

You have two unrelated problems at the same time.

For 157; low voltage at the MAF , , a cleaning should do the trick.

You can simply unscrew it and "carefully" pull it straight up out of the MAF housing, then just spray clean with "CRC MAF cleaner".

Here is the MAF pulled out. The two tiny sensor filaments should be shiny like a new nickle. (This pic is of a dirty Mass Air Flow sensor)

Note: there is no gasket on the MAF, metal-to-metal contact here.

For the 127: the TPS Throttle position sensor needs to be replaced. No biggie $50 at the AP store. Two screws and done.

The Yellow circle is the TPS.

Note: the red arrow points to the Idle Air Control valve (AIC)
The AIC can also be taken off and cleaned with the CRC MAF cleaner. This does have a gasket; reusable if not damaged taking it off.

So 50 bucks and a little time under the hood and you will be running smooth again.

 

[mom4teen]

Thank you FR-425. Yes, I realized that I had put the code issue in the subject heading and then changed my post in the subject message. As far as the codes are concerned, I had gotten a new MAF and put it on, then the vehicle wouldn't even idle and kept stalling. I continued from there and replaced the TPS but there was no change in the way the vehicle ran. I put the old MAF back on and now it runs fine. When the new MAF was on it I was getting codes 1214, 157, 158 and 332 in the CM mode. I haven't checked for codes since then but I will go ahead and clean the old MAF and IAC.
I still have a problem with the low idle and the engine dying when it is first started. That has been an issue since several months after putting the new PCM in.

 

[FR-425]

I'm beginning to think the "new" PCM may be bad. Or maybe the wrong one.

That's a lot of codes that all pertain to voltage to HIGH.

Lots of random unrelated codes or different codes on repeated tests usually means; bad PCM.