I honestly dont know. The guy told me it was a custom tuned pcm ordered from gm performance that was tuned for the lt4 swap. The scanner showed it idleing between 980rpm-1040rpm, which was close to what my rpm gauge was showing. It also appears that this z28 is sucking down some gas . Not good with premium prices. Im thinking of maybe turning down my fuel regulator (any comments?)
Id like to lean it out a lil mostly because I can tell its running a tad rich. I just filled up yesterday and ive been 120 miles and already at 1/2 tank. my 94 TA was automatic and it still pulled out 25mpg. ?? and this z28 is a 6speed, i dont get it!

 

I would drive back and forth to school on a few wknds, 170 miles one way and it would take me down only about 1/4th of a tank one way.

But that was also with a lot of highway miles coasting in 6th gear at 1300 rpm's I think it was.

 

When I try to coast in 6th gear @ 60mph mines running 1450-1500 rpms. I go to school 50min away, so mon-thurs ill be doing 50min to school, n 50 min back. So i was atleast hoping for 23-25 mpg. And trust me ive been trying to coast in neutral but it only idles down to about 1000rpms because its idled high for some reason.

 

IDK if this will help you at all but since you asked to update you since our problems were sort of similar I am. I got my cable today and ran scans. Although the SES light has not been on through all these problems I still pulled 3 codes. Codes are 48(MAF failure) 42(EST grounded or shorted) and 22(TPS low voltage).

My TPS is new and I'll probably just have to slot it to make the corrections. I will replace my MAF sensor, but as for the EST shorted or ground idk how to mess with that since it's an array of things within the ignition control circuit and I've already tested my icm which passed and everything on the coil tested ok. But I don't want to hijack the thread I've continued this topic on my own thread and I can let you know if anything else occurs that may also help you.

 

What are the long term fuel trims for bank 1 and bank 2(scanner should tell you)?

 

Idk, I'll have to swing by my friends shop and hook it back up to the snap on computer, and try and check bank 1 n 2. I know it's running rich. I was curious about lowering the fuel regulator. Would that hurt it, I'm just trying to lean it out a bit