5ktq electrical issues update...

[Cody]

I think you misread a post somewhere. This has nothing to do with 3000rpm. The engine missfires at all rpms, even bad enough (depending on how low the voltage is) to where it wont run at any speed with any throttle position. If I let the car idle and do not touch the throttle then turn on say the parking lights and the voltage goes to 12.8v I get a slight missfire and the engine will drop about 100rpm, then if I turn on the headlights it will get more severe and either stall or get close to stalling, and highbeams will nearly always cause it to stall. If I try to hold it at any given speed using the throttle it takes more and more throttle to keep it going. When the lights are on w/ highbeams usually it will be missfiring so badly that at WOT it won't go past 3000rpm, then if I turn on the a/c it just plain dies no matter what speed or throttle position. This is all voltage related. At 12.8v it misses slightly, at 12.6v is where it will barely run and at 12.4v or under it ju!
 st shuts off.

-Cody


---------- Original Message ----------------------------------
From: Ameer Antar <antar at comcast.net>
Reply-To: antar at comcast.net
Date: Thu, 02 Oct 2003 15:49:45 -0500

>I'm not really convinced that it's voltage related, although it could be... 12.8v is fine for most ECU's...most will crank in cold weather w/ under 10V. The 12.8V reading maybe just b/c the unit is draining lots of current. It seems to me the simplest fact you can verify is that the problem is rpm related.. Anything after 3k is no good. and now we know that the timing is being retarded at that time. A decrease in voltage should not necessarily lead to a large decrease in advance. I'd run the Bentley tests on the IAT and CLT sensors and their wiring. Those wires are real thin and maybe have gotten corroded under the hood somewhere. That way you'll start narrowing things down. Have you ever tried swapping the ECU setup into another car? I wonder if the problem would be the same.
>
>-Ameer
>
>---Original Message---
>From: "Cody" <Cody at mail.craincorporated.com>
>Date: 10/2/03 8:35:32 AM
>Subject: Re: 5ktq electrical issues update...
>
>My problem is voltage related. The car only misses when voltage is at or under 12.8v. The knock sensor should not detect more knock just because the voltage is lower.
>
>-Cody
>
>
>---------- Original Message ----------------------------------
>From: Ameer Antar <antar at comcast.net>
>Reply-To: antar at comcast.net
>Date: Wed, 01 Oct 2003 21:57:09 -0500
>
>>I'm not sure what you mean by the knock sensor being voltage-related. Of course the ECU detects voltage from the knock sensor, but this signal is AC, not DC. It's pretty much like a microphone, so the sensor doesn't output a higher voltage when it detects knock, it simply outputs a signal that corresponds to the vibrations it detects. In this system the ECU actually detects for knock through the sensor, much like your brain can listen for knock through the use of a stethoscope The stethoscope doesn't detect the knock, it allows you to hear it; you detect it. Check the knock sensing wires for frays or missing or loose shielding connections. Any noise on the line to the ECU that's the right frequency and amplitude can be interpreted by the ECU as knock. Which reminds me, maybe the RF/IF radiation of the injector control transistors (or FET's, whatever) in the EFI ECU are making lot's of noise for the original ECU at higher RPM. Are they next to each other? Try separating the!
 m!
>  or shielding the EFI box in a seale
>>-Ameer
>>
>>---Original Message---
>>Date: Wed,  1 Oct 2003 16:54:42 -0400
>>From: "Cody" <Cody at mail.craincorporated.com>
>>Reply-To: <Cody at mail.craincorporated.com>
>>To: "Bernard Littau" <bernardl at acumenassociates.com>
>>Cc: <quattro at audifans.com>
>>Subject: RE: 5ktq electrical issues update...
>>
>>The OEM IAT is still in place as it was. The thing about that though was that when I first got the car (back in May) it ran quite bad off of the transporter into the lot here, so I took a look and saw the IAT was disconnected (wires cut), and I have had one of them break on another 5ktq so I knew its effects. I soldered the connection back which as we know didn't help my running issue (same issue still now). Last night I decided to try another sensor from a parts car which didn't help either. I suppose I should ohm out the wiring for the IAT tonight.
>>
>>What will happen if I just disconnect the knock sensor for a test? I was thinking about the knock sensor before, but I forgot about it. I'll read up on the torque specs and testing procedure in the Bentley right after the shop closes today.
>>
>>Only trouble with the knock sensor theory is that it its voltage related. I would figure if theres knock sensor issues it would be retarding constantly rather then only when theres enough of an electrical draw. I'll still take a closer look.
>>
>>-Cody
>>
>>
>>
>