ABY ECU Intermittent issue

[edge_devil]

Hi all,

I have searched and cannot find a similar thread, forgive me if I've missed one.

First off, this is an ABY engine with the type A ecu (no immob) and it's built into a kit car. The AC and P/S pumps are removed, the original wiring loom is in use but has been shortened (by me) and the ECU is chipped, not by me.

I have added a black box with an LED and switch connected to the engine light output from the ECU so I can simply check for errors using flashing lights.

With engine running I have run the ecu test using the led, and the system returns 4444, all okay.....but last week and a few other times the engine cuts out and won't start. This could be while idling or driving. What is apparent is when I turn on the ignition, before it start the engine when the ecu is playing up the LED flickers or doesn't light up at all. When things are working fine the LED comes on and shines a solid colour as it should.

After this long preamble, the question I have is, what could cause this issue? The normal ground and 12v and lose connections on the ECU I have tried, but are there any external components (knock sensor etc) that could cause this issue?

I used this site for most of my information: http://www.sjmautotechnik.com/troubl...ng/ecu20v.html

[UrS4boy]

Potential solutions to why your AAN/ABY/ADU isn't starting

.. After this long preamble, the question I have is, what could cause this issue? The normal ground and 12v and lose connections on the ECU I have tried, but are there any external components (knock sensor etc) that could cause this issue? /url]

You can start by reviewing the AAN ECU pin-out documented here:

http://forums.quattroworld.com/s4s6/msgs/21009.phtml (knock sensors are not your issue)

And then move on to this:

Potential solutions to why your AAN/ABY/ADU isn't starting:

http://forums.quattroworld.com/s4s6/msgs/210191.phtml

Good luck

[edge_devil]

Thanks, looks like I need to go through it all...ps car running okay ATM so waiting for it to go wrong..

On another note.... My fuel pump runs when I switch on the ignition, but doesn't just prime, it keeps running. I know that's not normal, but could it be the upgraded chips in my ecu causing this?

[UrS4boy]

...On another note.... My fuel pump runs when I switch on the ignition, but doesn't just prime, it keeps running. I know that's not normal, but could it be the upgraded chips in my ecu causing this?

Not normal and probably nothing to do with the chips. Depends how you wired things. If the fuel pump is "running" then it should be priming, i.e. pressurizing the fuel rail.

The intermittent ECU thing could be a flakey ECU ground or, if you are using the thermal fuse on the ECU power, a flakey thermal fuse (Change it out for a spade fuse).

[edge_devil]

I've kept the fuel pump wiring as standard, with the feed being switched by the ecu controlled relay. I think I need to check some wiring, especially as you say the grounds and now I think the relay too!

Fuses are standard blade, I'll drop a photo later on.

[edge_devil]

uploadfromtaptalk1398871060992.jpg

Although simplified compared to the original. ..it does the job



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[UrS4boy]

Although simplified compared to the original. ..it does the job

Not sure how you've wired things. Looks like S2/RS2 but I can't tell from that photo (see RS2 fuse map below). Is the Blue wire at the FP relay going to Pin T55/3 at the ECU?



RS2 Fuse box cover map:

[edge_devil]

I'm away from home until Monday so I can't check on the car, but yes the blue wire is from the ecu. The red wires are live feed, the black ignition key feed (and the small blue ones on the right also). Comparing the fuse numbers with the picture you posted things are correct. I need to check the ecu pin is correct, but I'm pretty sure it is.

Do you know how the ecu decides when the fuel is primed?

For the FP relay it's only got one in/out pair right, the other pairs are for the fuse override in the upper housing?


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[UrS4boy]

...Do you know how the ecu decides when the fuel is primed? For the FP relay it's only got one in/out pair right, the other pairs are for the fuse override in the upper housing?

Here is some info that I have put together about the J17 Fuel Pump Relay

http://forums.quattroworld.com/s4s6/msgs/22583.phtml

Bottomline, for the AAN, ABY and ADU, unless the ECU gets a signal from the G28 that can be interpreted as the cranking speed is over 13 RPM, the ECU will *NOT* energize the J17 FP relay. This means no power to the G6 fuel pump, the injectors, the G70 MAF (at least not full power) or the N71, N75 and N80.

[edge_devil]

Hi all,

So I have just been out and had a play and...... I made a wiring mistake an an incorrect assumption!

If you look at the FP relay pins 87 and 87a are switched via the relay and supplied by constant 12v from the battery rail in the fuse box. I assumed you could mix and match these outputs, you can't!

I had the fuel pump fuse and s28 connected to the same output pin on the relay, 87. If you follow the diagram you'll see s28 passes through the air mass sensor and cross connects via a hold over relay in the ecu, this was also powering the fuel pump... Oops!!!

I've now isolated the outputs from the FP relay as originally designed, although the lambda heater is switched via the ignition as per the original Audi 100, not as above, although I may change this later.

The big ecu plug still has an issue and I think this may simply be because of the sealing ring being missing, or the casting screw not being the original screw and therefore not the right size. It's working but it's temperamental so I'll need to run through that.

Due to an accident in my day to day car I can't risk going for a test drive at the minute as I can't recover myself! As soon as my daily drive is repaired I'll be testing again.


Thanks to your collective input, it is very much appreciated.


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[UrS4boy]

..So I have just been out and had a play and...... I made a wiring mistake an an incorrect assumption!If you look at the FP relay pins 87 and 87a are switched via the relay and supplied by constant 12v from the battery rail in the fuse box. I assumed you could mix and match these outputs, you can't!

Well that is good news.

Wiring is wiring. You have to stick with the original design intent or something will go kafluey elsewhere. This AAN J17 Fuel Pump relay diagram shows what you are talking about (where S72 = ABY S28 and S75 = ABY S24 and S17 = ABY S13)

[edge_devil]

I had a look at the ECU plug and the ECU location and have made a few changes... hopefully this will make my problems go away



Full article here:RussellWeb.EU

[edge_devil]

ECU Fault 1111

Ohh an update....

I just popped out, as I do now and again and check that the engine starts runs etc. It started, it ran, so I left it to warm up for a few minutes, then it stopped.... I have the Diagnostic LED in a blackbox attached to the loom so I held the button for 4 seconds and asked the ECU for a diagnostics code, the code I received was 1111.

Code 1111 - ECU

The ECU itself has failed one of its own diagnostic tests. The most common cause is a bad PROM checksum resulting from incompetent "chipping" - some companies apparently do not know how to recalculate the checksum after modifiying the boost tables. Remove the cover from the ECU, unscrew the upper board, and check that the original Hitachi PROM (it has a silvered sticker saying "MAC12") is still in place. The stock chip is soldered directly to the board - a modified chip will usually be in a socket. If the chip has been changed, a new chip with a correct checksum should be sourced.

Otherwise, check the ECU in a known good car.

Now I would have thought that ECU code 1111 couldn't be intermittent, it works or it doesn't because electronic components don't have bad days, its 1 or 0, on or off.

Anyone have any ideas how I can check the ECU I have, or a stock Chip I can drop in to replace the chipped one I have just in case this IS the actual issue?

[UrS4boy]

Your quote obviously is for an Hitachi ECU from a 10V turbo. Here is a 1111 code discussion relating to the 20VT Motronic ECU (similar to your quote):

•1111 (Blink Fault Code), 65535 VAG1551/2 Fault Code Number
Engine Control Unit (ECU) Defective memory circuits,
Incorrect Checksum for internal memory (EPROMs)
(this can occur on some modified ECU's) Check ECU ground connections, Check EPROM programming
Symptom: Check engine light may come on

Nothing about shutting the engine off. Are you sure 1111 was the only code and/or you don't have fuelling issue?

[edge_devil]

Nope fuelling is fine.... well saying that how would I know but I turned off the engine and restarted the car it started fine but still showed the 1111 code !

I'm going to check the ground connections as per SJM:

65535 1111 Engine Control Module Malfunctioning Poor ground connection to J220 at pins 10, 14, 18 or 24 / No voltage at pin 37 of J220 while cranking
Check J220 wiring, B+ and ground connections