ECU

[saysomestuff 0]

Hi All,

 

I have a 2.0l KE Jetronic 9A 16v C (still with me? :lol:)

 

Does anyone know exactly what information the OBD1 ECU gives out? i.e. what does it control?

 

I'm assuming it controls the fuelling by calculating optimal fuelling based on input from the different senders (o2, knock etc.).

 

I know it monitors revs etc but does it control them?

 

Also I guess it logs any faults with the ABS. Can anyone think of anything else?

[saysomestuff 0]

nobody? If i fit stand alone fuel injection and remove ABS do i need an ECU?

[RW1 0]

Summary:

 

16v 9A 2.0ltr Corrado

 

Understand first that there is more than one “brain”. When coupling up to the diagnostics, you are coupling upto a data bus on which hangs the individual ECUs. There are upto 4 ECU’s possible on a 2.0ltr 9a 16v Corrado – Engine, Autobox (see notes below for UK), ABS & Key Immbiliser (See notes below for application).

 

9A 16v Engine ECU.

 

Reads:

 

Lambda Probe, Coolant Temperature, 2 x Knock Sensors, Hall Ignition sender & Firing Point Sender, Airflow Potentiometer in the Airflow head, Idle & Full Throttle switches.

 

Controls:

 

Idle Stabilisation Valve, signals the ignition module to fire.

 

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To access the Engine ECU on the Corrado’s data bus, the PC isolating interface needs to be electrically isolated. Optical interfaces will not work. Secondly, the initial interrogation baud rate must be 4,800 baud for initial interrogation or the ECU chokes. To clear the choked ECU, back fully out of VAG-COM, switch the ignition off, pause, switch the ignition back on and re-enter the ECU at 4,800 baud rate. VAG-COM can be preset to this data bus speed.

 

The ECU is simple in operation. It has a defined set of fault codes in accordance with those used elsewhere on VAG cars but only those relevant to the engine, eg. 00515 – Hall Sender but be aware of differences using the same terminology! The Hall Sender G40 in the VR6 this is the Camshaft Position Sender, while in the 2.0ltr 16v it is the Hall Effect Sender in the Distributor. There are less fault codes programmed into the engine ECU than the VR6 as the engine electronic sensors & switches are fewer in number.

 

There is only one set of measuring blocks on group 00. It consists of 10 fields for Coolant Temp., Engine Load, Engine Speed, Idle Stabilisation, Lambda interrogation, Lambda adaption, Road Speed signal, Switch position condition - various, Calculated Ignition Firing point. These are all fields with values where a prescribed action sequence generates a number that has to be compared with a specification for that field to pass or fail relevant to the test. So unlike the VR6 ECU, they don’t resemble anything sensible, just a set of numbers jiggling about as the engine runs.

 

 

9A 16V - ABS, Autobox & Key Immobiliser ECUs

 

9A 16V ABS, Autobox & Key Immobiliser ECUs can all be interrogated with either an optical or electrically isolated PC interface & cable. The interrogation speed is ideally 9,600 baud rate but these units don’t choke if the wrong speed is used initially. VAG-COM will find them eventually on the data bus.

 

The ABS is without traction control but otherwise it uses the same components generating a similar subset of fault codes as the VR6.

 

The Autobox option is obvious, if it isn’t fitted, nothing to interrogate. In the UK, this option doesn’t appear to have officially been offered to customers but the Autobox does exist for this engine and was fitted to the UK 8v engine Corrados. The faults codes are the normal set. The Autobox ECU has to be “adapted” to the Engine ECU & Throttle Position Sender otherwise it will “jump” gears on auto change. ie. 1 to 3, 4 to 2.

 

The Key Immobiliser is only fitted to post October 1994 (chassis 50SK000719 onwards) – June 1995 (end of production) made Corrados. Very few fault codes. One group (Grp 001) of measuring block fields associated with seeing the key on engine start.

 

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[saysomestuff 0]

Thanks very mch RW1 - I knew you'd come through for me :D

 

I am essentially trying to figure out what info I could get off the ECU if I had some kind of interrogatino program for revs/temp etc.

 

excuse my stupidity in this question but as I have a mechanical dizzy, which fires each plug as it passes the node, how can the ECU retard ignition based on knock sensors.

 

Also, I'm assuming the MFA just crunched these numbers to come up with the info.

[RW1 0]

The ignition trigger passes through the ECU so the ECU must be set to fully advanced as an internal design value and then the electronics adjust it by delta retardation to suit according to the two knock sensor's feedback.

 

And I don't see any link of Engine ECU to ABS ECU other than the diagnostic bus common wires.

 

Coolant temp is Grp 00, field 1, revs are on field 3 but scaling as you will find is not a direct readout and a factor has to be applied plus it won't be accurate as the readings are truncated.

 

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