Differences between 7A ECU - 2 plugs

[mihai_antony]

Hello!

What are the differences between these 2 ECU, both with 2 plugs and both for early 7A engine?

893906266B
893906266

Many thanks in advance
Mihai

[Nuno_Cristiano]

Maybe other to NM engines?

[UrS4boy]

Hello! What are the differences between these 2 ECU, both with 2 plugs and both for early 7A engine? 893906266B and 893906266

In the beginning there was 893906266. 266 was dropped in favour of 893906266B on 31/12/1988. 893906266B in turn was dropped in favour of 893906266BA on 15/12/1990. All of these were 7A ECUs.

Some interesting reading:

http://workshop-manuals.com/audi/90_quattro_20v/l5-2309cc_2.3l_dohc_%287a%29/relays_and_modules/relays_and_modules_powertrain_management/relays_and_modules_computers_and_control_systems/engine_control_module/component_information/technical_service_bulletins/all_technical_service_bulletins_for_engine_control_module/249102/

Subject: Engine - Minor Load Slap In Drive Line Occurs When
Changing From Deceleration To Acceleration While Driving

Model(s): Coupe Quattro, 90 Quattro

M.Y. 1990

Condition: Deceleration fuel shut-off remains momentarily activated during acceleration.

Production: Introduction of improved ECU software for MPI engine management system. ECU P/N 893 906 266D

As of: April 1990

VIN: 8A_LA208061 ; 8B_LA13615

Service: A) For vehicles produced after the above
date/VIN, the new style ECU (893 906 266D) should be used.

B) For vehicles produced before the above
date/VIN, replace ECU 893 906 266B with P/N 893 906 266BA (ECU has improved software to correct shortcoming)


Accessible reference to BA PN = http://audi.7zap.com/en/rdw/audi+80+.../906-115010/#7

The NM ECU was something else entirely with PN 811906266.

[quattrito]

Yes, NM ECU was completely black and with red code label if I remember correctly.

[UrS4boy]

The NM ECU was something else entirely with PN 811906266.

Yes, NM ECU was completely black and with red code label if I remember correctly.

[mihai_antony]

Thank you guys, a lot of useful informations
I have the first release 893906266, I will check for the 893906266b or BA

Mihai

[A1QSHIP]

Allegedly, the later 7A ECUs were tuned for more horsepower. This was done to compensate for the switch to a cast iron exhaust manifold from the tubular exhaust manifold found on the early 7A powered Coupes. I put a tubular exhaust on my Coupe & it did seem to wake it up a bit. Sounded better for certain.

[Bowie69]

They were of a different tune, yes, as well as having 4 ECU plugs, not 2

The book figures were still 3BHP down, to 167BHP on the cast manifold motors, so the tune couldn't really compensate the good headers.

and yes, I have the tubular manifold on mine ('91), after I found the cast one was cracked underneath, no wonder it made lotsa noise...

[Bowie69]

They were of a different tune, yes, as well as having 4 ECU plugs, not 2

The book figures were still 3BHP down, to 167BHP on the cast manifold motors, so the tune couldn't really compensate the good headers.

and yes, I have the tubular manifold on mine ('91), after I found the cast one was cracked underneath, no wonder it made lotsa noise...