Sélection d’un remplaçant EPM/MEMCAL


les composants de ECM

ECM – Un gros problème avec le V8 5.7 LT1 de Chevy

What I know about the 1992/1993 Corvette LT1 ECM and MEMCAL —–

92 & 93 Corvette’s ECM and the 93 Camaro’s & Firebirds all use the same ECM.

The Correct ECM for a 92-93 Manual shift Corvette would be a ACDelco # 16159278 or the GM part # 88999183.

The Correct MemCal for a manual trans Vette’s ECM would be ” DELCO BAFN 3876 ” and if your ECM requires repairs, In my opinion, the best place to have it Tested and Repaired is Cardone.

It’s important to keep in mind that the 92-93 ECM is different from the 94-95 ECM and the 96 ECM is different from the 2 others. It seems that the 96 ECM it is the only ECM that is 100% ODB2 compliant. For this one reason alone, I suggest to those wanting to purchase a C4 to buy a 96 LT1, LT4 or any year ZR1. Again, only my opinion.

Based on the 31 year history of enjoying my 92 (purchased new in 92) it has been a very dependable & reliable machine.  Zero regrets.

However, back in 2007 I shipped the Vette to LPE in Indiana to have them work their magic on the motor and when the Black Prince returned home the motor had grown to 383 ci and gained another 140 ponies, torque increased to 430 with 395 WHP. But, age is catching up to the Prince and some parts are becoming more difficult to find – such as the 92-93 ECM, not to mentioned that when the Prince gained his extra HP, LPE calibrated a New EPROM for the ECM Memcal component. And, what to do if something should happen to the one and only modified LPE EPROM? Anyway, after searching for months I finally located an ECM out of a 93 Manual Vette and as we know the 92-93 are the same units (but the Memcal is specific to whether your ride is a Manual or Automatic ….. so take care when purchasing a Memcal). My next step was to find a local Electronic Auto repair shop, which I did, and they were able to duplicate my LPE EPROM and run tests of my newly purchased backup ECM. So, for the moment I now have a 100% compatible ECM as a backup  to the original one from LPE. I have swapped the two back and forth and the Vette performs equally well with either of them installed.

As it seems the holy grail of a LT1 ECMs is the ODB2 compliant found in the 96 – Do I know of anyone that has installed a 96 ECM in a 92-93 Vette. NO, not sure if this conversion has ever been done?  As I have not as yet to find anyone in any Corvette Groupe or any other LT1 group, provide any first hand knowledge, and based on what little I know – it appears that one would have to change at a minimum the WHOLE engine wiring harness…. and then it would seem one would have to REPIN the new harness to the PCM. There is documentation available to assist one do this, but is seems it would be a rather tedious task.

ALSO, as the 92 – 93 LT1 injectors are bank to bank firing, and the 94+ FLASH PCM are sequential firing, ALL the injectors would have to be rewired too. And, I believe when all of this is completed the signals from the Opti should work fine as well as all the other sensors. BUT NOT SURE.

Again, this is what I think I know and not what I can say is absolute.

Info on the 92/93 MEMCAL module.

The MEMory and CALibration (MEMCAL) device is a blue colored plastic Removable Unit that is located on the underside of the ECM and is found by removing it’s housing plate. MEMCAL is it’s general term for the components within; 1) a 27C256 EPROM and 2) it’s back-up fuel control system consisting of an IC and it’s analog circuitry.

The EPROM mostly contains the “fuel air calibrations” values along with several other base settings, such as the rev and speed limiters, etc. Note: It’s very important to use the correct Memcal dependent of the transmission – Manual or Automatic!

** That is mainly what I know about the device. I am not familiar about how one goes about making modifications to the EPROM’s data, which is referred to as a Tune (tuning). But it seems this process is much more complicated for the 92 – 93 than for the 94+ ECMs, therefore the necessity to have a complete backup ECM when your unit fails at some point in the future years! My thought anyway – be prepared as it will happen.

I believe Corvette Central wants to sell some parts and or services or both….. Click this link to see an ECM Unit and when you remove the four (4) screws on the underside you will find/see the Memcal.

1992 1993 LT1 5.7 Corvette Camaro Trans Am ECM PCM Computer ECU 16159278.

Again, the complete unit is the ECM and the EPROM not EEPROM (big difference) is the blue component inside the ECM and then inside the Blue Memcal you will fine the EPROM.

FYI – I purchased my 92 back in 1992 and the EPROM was aok for 15 years. Then in 2007 LPE modified the LT1 and the years since then the modified EPROM has worked flawlessly. Don’t know what else I can say ….

Alternate solutions that I am aware of but have not used nor spoken to anyone that has done so.

Other solutions available today for controlling your early LT engine is going to be with a 24x kit from eficonnection being driven by a Holley Terminator X ECU. This kit: 24x/1x LT1 Bundle – Holley Terminator X for Universal LT1 Engines – EFI Connection, LLC

There is a kit that includes a Holley HP ECU that allows for better logging and stuff but for a higher cost: 24x/1x LT1 Bundle – Holley HP for Universal LT1 – EFI Connection, LLC

This will correct controller problems, wiring or harness problems, optispark problems, and it will give you tuning capabilities. This setup will also bring new options like the ability to add or delete sensors as you see fit and also will allow for sequential fueling instead of batch firing a whole bank at a time.

Another possible source for reprogramming your EPROM would be TunerCATS – http://www.tunercat.com/ , and again have not used their products or solutions.

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