MC2 running lean

[Mark Rosenkrantz]

Basically CIS-E, right?  It's admittedly been a while for me.  How about timing?  Incorrect timing by ECU or engine itself can also cause a lean mixture.  If the fuel really is spot-on, then it is too much air, pre-ignition (pinging/knocking), engine timing, or spark timing.  Did I miss anything?

Mark Rosenkrantz
Typos sent from my iPad

On Mar 7, 2012, at 2:00 AM, "Steve Buchholz" <urq at pacbell.net> wrote:

> MC-2 is still based on CIS, there really isn't that much the ECU does to control mixture.  If you disconnect the OXS fueling is completely mechanical.
> 
> You say that you tried everything, did that include checking the fuel and control pressures?
> 
> Sometimes a problem in one cylinder can affect the operation of all. How do you know the whole engine is running lean? Have you checked spark plugs?
> 
> I realize that you say that you have tried everything, but without a comprehensive list of tests and results anything any of us can recommend would not be much better than a shoot in the dark. That said, I think the likelihood that the ECU is causing a lean running condition is low.
> 
> Steve Buchholz (mobile)
> 
> ----- Reply message -----
> From: "Dag Bøsterud" <dag.boesterud at little-e.com>
> Date: Tue, Mar 6, 2012 2:35 pm
> Subject: MC2 running lean
> To: "'Mark Rosenkrantz'" <speedracer.mark at gmail.com>
> Cc: <quattro at audifans.com>
> 
> 
> Noo. Can't get hold of a MAC-14.
> I can buy one off of eBay from Germany, but some seller will charge me like €425. I won't pay that.
> That's way too expensive.
> 
> Do you have a spare?
> 
> /Dag
> 
> -----Opprinnelig melding-----
> Fra: Mark Rosenkrantz [mailto:speedracer.mark at gmail.com] 
> Sendt: 6. mars 2012 23:30
> Til: Dag Bøsterud
> Kopi: <quattro at audifans.com>
> Emne: Re: MC2 running lean
> 
> Yes, have you swapped it?  If all other reason fails, I often look at the ECU as the issue.... Sometimes, it is!
> 
> Mark Rosenkrantz
> Typos sent from my iPad
> 
> On Mar 6, 2012, at 5:22 PM, Dag Bøsterud <dag.boesterud at little-e.com> wrote:
> 
>> ECU like in Engine Control Unit :p
>> 
>> /Dag
>> 
>> 1990 Audi 100 Turbo Quattro Sport Exklusiv
>> 
>> 
>> -----Opprinnelig melding-----
>> Fra: Mark Rosenkrantz [mailto:speedracer.mark at gmail.com] 
>> Sendt: 6. mars 2012 23:11
>> Til: Dag Bøsterud
>> Kopi: <quattro at audifans.com>
>> Emne: Re: MC2 running lean
>> 
>> ECU?
>> 
>> Mark Rosenkrantz
>> Typos sent from my iPad
>> 
>> On Mar 6, 2012, at 4:52 PM, Dag Bøsterud <dag.boesterud at little-e.com> wrote:
>> 
>>> I've for a long time been troubled with my 1990 Audi 100 TQ MC2-engine
>>> running very lean. From June last year the car has been virtually
>>> undriveable. You name it, I've replaced it, tested it and tried it. Hoses,
>>> sensors, injectors, fuel pump, filters... brand new and double checked.
>>> 
>>> 
>>> 
>>> I read on the SJM-page that if you disconnect the temp sensor for the ECU,
>>> the car will run rich and pulse the cold start valve due to the fact that
>>> this is an NTC-sensor.
>>> 
>>> I disconnected the sensor in my car, and the car won't start. No way. Quite
>>> the opposite of what it's supposed to do...
>>> 
>>> 
>>> 
>>> ...how can this be???
>>> 
>>> 
>>> 
>>> /Dag
>>> 
>>> 1990 Audi 100 Turbo Quattro Sport Exklusiv
>>> 
>>> _______________________________________________
>>> quattro mailing list
>>> http://www.audifans.com/mailman/listinfo/quattro
>>> http://www.audifans.com/kb/List_information
>> 
>> 
>> 
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> 
> 
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