94 PCM (D4U1) In My 93 Causing Codes

[Winterhawk]

The title says it all...LOL
Just replaced my 1993 PCM with the D4U1 and now I'm getting codes for the EGR system. Put my old PCM back in and it is fine. I wanted firmer shifts. About $85.00. So I bought another D4U1 from RCM for $79.00 and it will be in next week. Anybody else had this problem?

 

[whiteguy3]

I have heard of this happening before. Fairly rare issue, but other than that I have heard of it happening.

 

[Winterhawk]

My newer RCM Automotive D4U1 PCM arrived and I installed it. No EGR codes with this one. Guess I have 3 others to get rid of now. 2 H3Z's or the latest one out in 1993. Not sure if the other D4U1 is OK or not. It ran fine but caused my CEL to come on with the EGR codes. As far as the shift points? Not sure if I can tell a difference. I have 1,000 miles so far on my Certified Transmission and it seams to be getting better with time. I wouldn't let them install the line riser Resistor on the ATX yesterday.

 

[93_SHO_FL]

Thank you for this!! I just ordered some RCM parts!!! Similar symptoms as you.