5ktq electrical issues update...

[Cody]

Last night I decided to double check what my dad was seeing with the timing. I dunno what he saw, but I noticed 2 things.

1)It didn't retard like he said it did.
2)You can clearly see with the timing light at night sporatic missfires. Even just with the car idleing and no extra electical stuff on and the engine not audibly missing you can see that about 1 out of every 5 or 6 times the plug doesn't fire.


So last night I had an EE friend over helping me. We went through testing all of the grounds, everything good. Checked all of the Mac-11 feeds and grounds too. Then powered the EFI off the battery with a test lead (no time to do relay yet), which didnt help. Then we powered the injectors directly off the battery and the car seemed to be fixed. During all of this it was charging to 13.8v and dropping only down to 13.3 at the lowest with A/C and lights w/ highbeams. With the injectors not off of the ignition switch the car wouldn't miss at all, so I wired in a relay and put everythong back together (door panels were off for window issues, most of the dash was out for testing stuff) and went for a 5 minute cruise arround the shop. All was good so I decided to take a longer ride, so I called a friend and put him on resue alert in case it died on the road, then went driving for an hour. I got stuck by 2 trains near a station doing 5mph and was idleing for a good 20min of that hou!
 r. About 45 minutes in I started noticeing the car was missing momentarily as the rad fan turned on, but then it would be ok once it was running. I looked over at the computer and the voltage was back down to ~13.3v cruising, 12.9 when the fan turned on. 5 minutes later (I had turned arround at this point) it got to the point where when the fan turned on I had to turn out the lights to keep the engine running, and voltage was going to 12.3v when the fan came on. I did end up making it home, albeit barely.

I'm confused. Seems theres 2 problems, 1 with intermittent charging, and another with something not getting enough voltage when the battery is at or below 12.8 causing the miss. Seems when it charges right it charges enough to mask the missfire issue by keeping the voltage up above that 12.8v mark.

-Cody


---------- Original Message ----------------------------------
From: Huw Powell <audi at humanspeakers.com>
Reply-To:  audi at humanspeakers.com
Date: Thu, 02 Oct 2003 00:57:16 -0400

>
>> 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.
>
>A miss results in unburnt fuel making things look "rich," but also
>leaves oxygen in the exhaust stream provoking your OXS to register some
>O2.  So it can be confusing.
>
>You need to figure out if it is *really* "missing" somehow...
>
>--
>Huw Powell
>
>http://www.humanspeakers.com/audi
>
>http://www.humanthoughts.org/
>
>