I have a 91 TA. The ECM throws a code for the ignition control module. I have replaced the ECM and the PROM. When the check engine light comes on, it severely retards the timing, sometimes to the point of throttle body backfiring. I have looked in several service manuals and I still have no location for the ignition control mod. Everything I have read shows one in the 90 and earlier, but nothing for the 91.........help please.

 

its in the distributor.. take a 5.5mm socket to take it out

 

I forgot, ... that's been replaced as well.

 

well what codes are you getting?

 

I get a code 43

 

that is a knock sensor code DTC - 43 Knock sensor error

that would explain why your cars pulling timing...

 

Knock sensor failure is common. An open or short in the knock sensor circuit can cause the same symptom. Basically, the ESC module, or ECM on systems without the module, expects to see a certain amount of noise from the knock sensor. If the knock sensor picks up a higher level of noise, the ESC system pulls out timing(up to 18 degrees) til the noise goes back to a normal level. If there is a mechanical failure in the engine or other issue that continues to produce a high level of noise, even with timing retarded, the ESC system will default to full retard and set a code 43 in the ECM.

If the knock sensor circuit becomes open or shorted, so that no noise signal is received knock sensor, the system will again default to full retard(18 degrees) and set code 43 in the ECM.

First, listen carefully to the engine while idling and under load. Listen for any unusual noise. If the engine sounds normal, proceed with ESC diagnosis.

Look closely at the ESC system on your car to determine whether or not it has an ESC module external to the ECM. Locate the diagnostic flow chart for code 43 for system with module or without module, depending on how your car is equipped, follow the flow chart. You will need a scan tool and a DVOM for the tests.

Or just replace the knock sensor after checking wiring and connectors, and verifying no unusual noise.

 

it is an intermittent issue. when the ECM doesn't set a code and retard the timing, it runs like a bat out of hell, with no noises and no problems.....

the Knock sensor is also new.

I'm about to the point of selling it cause I can't figure it out..{Banging head against wall}

 

Check wiring and connectors. Intermittents are caused by either bad connections or shorting wires.

 

Totally agree with ASE DOC since its a new knock sensor