I just bought a pretty nice 1991 Z28 1LE from a fella who knew what it was... sort of. What he didn't know (and neither did I tip recently) was the 1LE had a special PROM? So just as I'm about to pay the guy I ask if he has changed anything on the car since he owned it. He says, "Ya I had to put a new ECM in it just last month." And he didn't keep the old one. So that 1LE PROM is gone! Anybody know how to replicate it? Keep in mind that I know zip about this stuff. Maybe its easy, maybe not. That's why I need you guys.

So It's 1991 Z28 1LE with the 5 speed MK6 (which I've read has a unique 5th gear just for 1LE) It has GU6 3:42 rear end gears.

EDIT: After posting this there are some guys out there who are telling me the 1LE did NOT have a unique PROM. Does anybody have a definitive answer or know of a reliable source for 1LE info? Who's the 1LE guru?

 

In for info as well.

 

Not true. My '89 has a MK6.

 

Good to know. Perhaps I either misunderstood what I read or that particular article was incorrect. Which is why I rarely repeat what I read without adding the disclaimer that it was something I read. Unless I have seen it with my own eyes and have solid proof. Too many people just regurgitate something they heard or read and then spread that around as the final truth.

 

Figuring that your car is a TPI setup (LB9), the PROM is located on the MEMCAL within the ECM. It is a pluggable piece that should have been moved over to the new ECM. See the sticky on the DFI & ECM board here for a picture of a MEMCAL.

When a reman ECM is purchased they don't have a MEMCAL, PROM, and sometimes no CALPAK installed. They need to be moved over from the old ECM.

Try this: while observing the SES/CEL light do a key-on, engine-off. The SES/CEL should turn on briefly, blink off, then turn on solid. Can repeat the test after at least 10 seconds of key-off.

If the blink-off occurs then there is a PROM/MEMCAL in the ECM and the ECM is running from it. In this case remove the small cover (2-screws) and get the BCC (4 LETTER code) from the silver label on the PROM. Post it here. Can also take a picture of it and post here.

RBob.

 

Like Rob said, if the previous owner replaced the ECM then he more than likely transferred the original prom over to the new ECM.

 

The car runs OK. I just don't know if it runs optimally. It tends to surge up and down during mild to heavy deceleration without the trans engaged, such as a freeway offramp with the clutch in. My 3rd gen cars don't do that. I will run this test AND get the code off the PROM and post it. TY

 

As soon as he told me he swapped the ECM I asked if he also kept the old ECM and he asked why would he do that. And then I told him I thought the "chip" was unique and he said he didn't know that. So the original chip is gone. TY

 

I'm no third gen expert (actually a 2nd gen guy)... but wasn't the 1LE just suspension and brakes?

I didn't think they had engine modifications... in which case, it should just be standard PROM for that year car.

Which also means your driveability issues are most likely mechanical/electrical problems rather than calibration problems.