5ktq electrical issues update...

Ameer Antar antar at comcast.net
Wed Oct 1 15:19:00 EDT 2003

Maybe the knock sensor is triggering and retarding the ignition too much. If the ECU thinks the engine is knocking and nothing changes that, the ECU will retard the timing all the way, which is not good to run w/ for long periods. This can damage exhaust components b/c the ignition is occuring so late in the cycle. I'm not sure but maybe someone has figured out how to tell when the MAC ECU's are sensing knock, or maybe that was a different ECU. Just a thought...


---Original Message---
Date: Wed,  1 Oct 2003 08:50:54 -0400
From: "Cody" <Cody at mail.craincorporated.com>
Reply-To: <Cody at mail.craincorporated.com>
To: <quattro at audifans.com>
Subject: 5ktq electrical issues update...

Ok well I got to work on the car for real yesterday. I did play with it some Sunday, but didn't really do much. Ok so last night I put the timing light on it (should done this a while ago) and checked to make sure that while missing if it still has all 5 plugs going. It does. Now this is where it gets weird. With the battery topped up as it is now I have to turn the a/c on to get the rad fan going AND turn on the lights to get a slight miss, then highbeams gets a good solid miss that wont rev above whatever rpm it was at when you hit the highbeam switch. Trouble is that now it seems as if the problem isn't that its loosing spark. Quantity and quality of spark seems perfect or at least as good as it needs to be. What is confusing me is the fact that when the engine is missing its dumping black smoke and showing every sign of being rich except the O2 sensor reads as ever so slightly rich at about 5v at idle with it tuned for a slightly richer 5.5v at idle. Even once I've leane!
 d it out significantly for a test it still acts rich (but reads lean). Now timing is under question. I was in the car keeping it running and switching the lights and such on/off while my dad was checking the timing. He says it was ~0 TDC at idle and advanced as it should when I sped up the engine (didn't note how much now that I think of it), but he says that when I hit the lights and it started missing that the timing reversed and went to retard at all rpm. Could it be retarding enough to cause a miss? What would cause this? Checked the hall earlier in the day and it read perfect (4.3 on the 4v+ spec pins 1+2, 11.5v to the 9v+ spec pins 1+3).

My dad keeps telling me that he thinks all 3 of my spare Mac-11s are bad. He says that in his experiance they go bad left and right, claiming one story of a friend that went through 3 in a year before selling the car. I've never heard anything like this, and never had one hicup on me. Any truth? I still doubt I've got 3 bad. Just to satisfy his mind are there any listers with 5kt's in the Delray Beach/ Boca Raton area that would mind stopping by for a second sometime to let me rty your Mac-11 in my car? I have seen 2 arround town (one goes into a neighborhood a block away from me) recently (and an 80 yesterday, first one besides mine I've ever seen).

Oh I forgot to mention that for this test the EFI was drawing its power directly off the battery, no longer through the MAC-11s power feed. Ground is still 4 wires with 2 ring terminals bolted to the chassis.



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