Lurked for awhile, finally joined.

I've got a 5.7tpi (90-92 map) and 700R4 swapped into a first gen S10. It's controlled by a 7730 ecm. My ses is on, but I cannot get the ecm to communicate to the aldl port with a scanner or the light to flash with a jumper. I've traced the wires, and checked continuity, from the aldl port to the ecm, and all look correct according to shoebox diagrams. The engine runs real strong, but very rich. I've replaced the ect and o2 sensors to try to get it to run leaner, but I think I really need to know what the ecm is doing, to really get it sorted out. Could the ecm be bad? What other symptoms might I be seeing if the ecm went bad? TIA

 

To see if the ECM is running from the PROM do this:

While observing the SES/CEL light key-on, engine-off. The SES/CEL should turn on briefly, blink off, then turn on solid. To repeat the test key-off for at least ten seconds.

If the CEL/SES doesn't blink off, then the ECM is in limp mode.

In this case the PROM could be bad or the ECM could be bad. Note that the '90 - '92 f-body's have VATs. So to bypass then there would need to be either a custom PROM burn or a bypass box installed.

It may be that the PROM is just missing from the MEMCAL. This will allow the engine to start and run in limp mode.

RBob.

 

Thanks, RBob. The SES/CEL comes on and does not blink. I conclude I am in limp mode.

The one piece of documentation I got from the PO is a receipt for a custom chip from 2008. I called the tuner and he looked it up and said he tuned for a bone stock 92 Camaro, 7730 ecm, 700R4, and deleted the VATS.

I opened the ecm today, pulled the cover from the MEMCAL. There is a PROM there, and it has an alum foil sticker on top that has "AVJP No VATS 5-7" handwritten on the foil sticker. Next step?

 

Actually, AUJP (not V, hard to tell sometimes).

Your choice, the ECM could be bad or the PROM could be bad. Just need to test each separately to tell.

RBob.

 

Thanks for clarification on AUJP. Is there a test for prom or ecm, other than the swap test? I hate the thought, but EvilBay has a 91 z28 ecm with AUJP prom listed near me. Is ecm 16198262 the same as my 7730? Will my harness work? Downside, other than another chip burn to remove vats?

 

Im new here but having a similar problem. I installed an 87 305 tpi in a 66 caprice lots of fun to drive, been having a problem with the idle.

 

monitered with snap on scanner, when the ecu communicates with scanner it runs fine, no codes, then while driving the scanner will blink and Ill get 4 to 5 codes one of them is 51 prom error. will do the ses light test to see. looks like easy solution to this is to buy a reman ecu from o'rileys and hyperchip for the prom best bang for our buck..

 

The 16198262 is the same ECM as the '7730, just a newer number. Will be able to use it and the MEMCAL to see which one is bad on your current set up. If the ECM then can use the current MEMCAL.

If the PROM is bad then will need to get one with VATs removed.

RBob.