Excuse me if this is a stupid question with an obvious answer but I am currently restoring my GTA and decided to look at the internals of the ECU. Can someone give me some information on the below? Is it a stock ECM is it has an aftermarket chip?

Not stock. It's from Jet.

Any info or link to some more details on this JET chip?

How would I be able to know what's in the chip? Do you think this is one of those mail order chips? Can I simply remove it or would I need a stock chip instead?

It may or may not be a Jet chip. It appears that there was a label on it, but is gone.

With the window open it may have been erased and re-burned. At a minimum get a small square of black electrical tape and cover that window.

Had a thought, pop the cover off the ECM and see if the chip label is in there someplace. Maybe it just fell off?

RBob.

Your original EPROM is attached to the carrier you see in the pic. It by=passes your chip but uses a 90 degree header to connect your original NETRES. You will have to remove the case cover to see (or remove) the original chip. HTH!

Hi guys. Thanks for all the information. I actually plan to go into prom programming at a later phase as currently I am focusing on rebuilding the car. I do have some experience with electronics so hopefully I will grasp the subject once I focus on it. I did myself a standalone MP3 player back in the late 90s using PIC and interfacing a standard ATAPI Interface.

For now I will try to open the ecm case and see if there are any stickers and also take a peek at the bypassed prom. Will probably post pictures again.

I opened the ECM and found the original GTA PROM.
Pic below.
Question : if I want to put it stock and remove the adapter and chip I am assuming it will work stock correct? The car does not have a Catalyser most probably it has been disabled. Would they have made those changes inside the aftermarket prom or the stock one? Sorry if my question seems stupid.

Currently the PROM on top in the socket w/o the tape over the window is running the ECM/engine.

To put it back to stock pop the adapter out of the ECM socket, carefully pull the MEMCAL off the adapter. Then plug MEMCAL into ECM socket.

RBob.

So it means that any feature that might have been disabled or enabled such as smog pump checks, egr checks, etc would be in the Prom without the tape correct?

Yes, that is the PROM that is/was running the engine.

RBob.

Understood. Thanks for the info. Really appreciate it

Just confirm a few things before putting the stock memcal back into position then starting the engine. A lot of times users will install an aftermarket chip that was written for their new modifications, so be sure your base timing is set to factory specs, and make sure your injectors are stock in case the chip was written for larger injectors...

I am going to open the engine to change all gaskets. Will verify timing and injectors while I am at it. Thanks for the tip.