ABY ECU Intermittent issue

[quattrostyle]

Moet kloppen, ik ken 'm

Got Dutch roots?

prj has MAP sensors.

[edge_devil]

Yeah I lived there for 10 years, moved back to the UK in 2010. I've sent Nero a pm, I guess the chips are probably fine so it's likely to be my wiring

My profile photo on the left is actually in Naarden.....

[UrS4boy]

On a side note, where can I get the upgraded MAP sensors?

EFI Express is one source http://www.efiexpress.com/catalog/pr...products_id=82

[edge_devil]

Thanks man... Stooped question, but if I change the MAP will the chips need reprogramming?


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[newsh]

Yes

[edge_devil]

Just a quick video so you can understand the nature of the issue. I switched on the ignition after checking the gnd and 12 pins, & this is what happens when it's playing up...

http://youtu.be/7sz0eJJ7ulg

The clicking is from the ISV btw.

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[twoqu]

Just two quick observations.
The first is that the fuel pump relay looks likes it off a 10V not a 20V as it has the fuse provision in the top to iniate fault diagnosis. Can't remember if they are the same from a contact point of view. If so ignore!
Second any faults codes will be stored by the ecu until they are erased. Thats relatively easy with VCDS/Vagcom. The only other way is to remove the 12V permanent power supply to the ecu for say a minute of two.
Just wondering if you are chasing a ghost fault code in effect. Obviously if you erase a code and it comes back then its an issue.

[edge_devil]

The FP relay outputs seem to be the same, so I'm risking that as okay. Re the fault codes I need to read up on what's involved etc etc and the I'll make the loom and get the software and start reading it all out. I haven't got the original diag pins, two were on the loom one was gone but I can re create it by opening my black box with the led and adding an extra loom plug for diag.


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[twoqu]

I am wondering if the clanging of the ISV means its in limp home mode due to the seriousness of that code. Its a grey area what happens in limp home but one documented occurance is that the idle speed is raised to 1100/1200 which can only be achieved by full stop activation of the ISV.
Nothing to lose. Temporarily power down the ecu and then reconnect and try. If the code comes back we will at least know it a current one!

[edge_devil]

I unplugged it afterwards and made another video I haven't posted and she ran fine.....then stopped again after two minutes. My gut feeling is a dirty/dry join in a cable or an unseen ecu issue.

I'm trying to have to avoid taking the body off, it's a 4 hour two man job, but if I have to I will and then go through all of the loom piece by piece again..... Sigh....

I do really appreciate the support in this forum, it's just a frustrating issue!


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[twoqu]

So effectively erasing the code (by removing ecu power) allows the engine to run for 2 minutes before presumably the same code comes back. There does seem to be three variables. Ground or power issues and of course the unseen properties of the chips! Hopefully soon you can eliminate as least one of those!

[edge_devil]

Ineed Robin, thans again m8, I'm crossing my fingers that it's the ecu, although a pain at least the issue will be solved!

[twoqu]

I was wondering why it says to check voltage with ign on at pin 37. This is to do with the holding relay. Rather than trying to explain, I suggest you take a look at Dave's explaination here:

http://forums.quattroworld.com/s4s6/msgs/102009.phtml

[UrS4boy]

I was wondering why it says to check voltage with ign on at pin 37. This is to do with the holding relay. Rather than trying to explain, I suggest you take a look at Dave's explaination here:
http://forums.quattroworld.com/s4s6/msgs/102009.phtml

Thanks Robin for providing Tim with that link. The holding relay is one of the more important secrets of the ECU function. From that link:

"When testing to see if the Holding relay is working, when you turn the ignition on, there should be 12v power to the injector terminals connected to the black wire with the red stripe (probe the connector with only ONE mulimeter probe, ground the second multimeter probe to the cam cover)."

[twoqu]

Think this is overlooked. Not only does it provide power to all the components prior to cranking/running but of course it allows the output tests which are conducted with just the ign on.
The two way supply is a bit confusing. Wonder when the holding relay drops out of the loop. During cranking/running?
Once the car is running it shouldn't have any input until its needed for the maf burn off after engine off.
Its a bit confusing looking at the schematics as power is fed out of pin 37 back up to the fuse box with ign on and then back down from the fuel pump relay when running!