5ktq electrical issues update...

[Cody]

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


---------- Original Message ----------------------------------
From: "Bernard Littau" <bernardl at acumenassociates.com>
Date: Wed, 1 Oct 2003 12:28:20 -0700

>Hi Ameer,
>
>What you say is technically correct, the ignition may be close to fully
>retarded, but not quite fully retarded.  The odds of that are vanishingly
>small, though.  As long as the ECU hears knock, it retards, so unless the
>knock goes away due to the retard action, the ECU will always hit maximum
>retard, and throw a code and flash the check engine light.
>
>If the knock sensor is damaged or mounted poorly, odds are it will signal
>knock independently of the retard.
>
>Your point about the air temp sensor is a good one.  What did you do with
>the original air temp sensor for the MAC-11, Cody?  If the wires to the
>MAC-11 air temp sensor are open, the ECU will think the resistance is
>infinite, which it interprets as very, very, hot intake air -- this will
>cause lots of retard.  The signal from the original ECU engine temp sensor
>is also still important, to wit:
>
>(From sjm's site:)
>In some cases the sensor can be intermittent when the engine warms up, which
>will cause some strange rich running conditions because the ECU will
>occasionally think the engine temp is much colder than it really is.
>Although it is not stated anywhere in the Bentley service information, the
>ECU will operate the cold start valve briefly as you begin accelerating when
>the engine is cold with a coolant temp below 150F. If the sensor is
>intermittent, the ECU may activate this cold start valve when the engine is
>warm and this will make the engine run very rough.
>
>Food for thought...
>
>Bernard Littau
>Woodinville, WA
>'88 5ktq
>
>
>
>
>> -----Original Message-----
>> From: Ameer Antar [mailto:antar at comcast.net]
>> Sent: Wednesday, October 01, 2003 1:00 PM
>> To: Bernard Littau
>> Cc: Quattro List
>> Subject: RE: 5ktq electrical issues update...
>>
>> Maybe the retard is not maximum, but still retarded a good deal, so no
>> error shows. It might be worth cheking proper torque of the knock sensor
>> bolt. Maybe something wrong w/ the air-temp sensor? I'm just trying to go
>> over what would cause an ECU to retard like that. Anyone else think of
>> anything that causes timing retard???
>>
>> -Ameer
>>
>> ---Original Message---
>> From: "Bernard Littau" <bernardl at acumenassociates.com>
>> Date: 10/1/03 1:44:47 PM
>> Subject: RE: 5ktq electrical issues update...
>>
>> >
>> > 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...
>> >
>>
>> This kind of knocking would throw a code and flash the check engine light
>> on
>> a MAC-11 car.
>>
>> Best,
>>
>> Bernard Littau
>> Woodinville, WA
>> '88 5ktq
>
>