[rfmaster]

Originally Posted by TravisMartin

Is the 7427 not compatible with a 4L80E? I musta misunderstood?

Travis

I did a bit of research into 7427 PCM which is by no means complete. From what I was able to find 7427 PCM was used with different power train combination's. For light and medium duty $0D EPROM mask id was used for 1500 and LD 2500 running the 4L60E transmission (and manual). For heavy duty applications with 454 with 4L80Es $0E or $31 EPROM masks were used in 7427. Interesting enough 6395 and 8625 PCMs were superseded by 7427 in LD applications.

For example in 95 GMC 3500 van 350 TBI with 4L80e 7427 PCM was loaded BNKM EPROM. There is little difference between in engine variables between $0D, $0E, and $31, however 4L60E and 4L80E trany code is different (one of the valves logic is flipped) and there is a harness difference between PCM and trany.

For JY picking - 6395 or the 7427 running the $0D mask were used with 4L60E. The HD trucks and vans (3500) used the same PCM's but ran the 4L80E and either the $0E mask in '94 or the $31 mask in '95. IMHO if you modify the trany wiring harness from 4L60E to match 4L80E (extra sensor and different logic) with appropriate .bin and mask, it should work great. More research....


Port fuel modification (i.e. TPI, etc) involves modifying injector driver circuits. I have not looked into it, but Fast355 runs 305/TPI/4L60E with 7427 in a full size van!! Check out his Youtube videos.

//RF