200 might be sick again, then again.....

[Kurt Deschler]

I agree that the check engine light is likely the result of knock in one 
form or another. The potentiometer that I was referring to the CIS 
potentiometer, which is only important on CIS-E cars. The throttle 
position switch is unlikely have any direct effect on this problem. 
Disturbing the knock sensor should be a last resort once all other 
possibilities are eliminated.

 	-Kurt

> Message: 7
> Date: Wed, 1 Nov 2006 20:18:40 -0500
> From: "E. Roy Wendell IV" <erwendell at mac.com>
> Subject: Re: 200 might be sick again, then again.....
> To: quattro at audifans.com
> Message-ID: <9A0C3CD0-BF5D-4701-A3F2-6C00A00DE0CB at mac.com>
> Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed
>
>
>>
>> The potentiometer on the MC2 is only used by the MFI and can be
>> ruled out.
>> I have had symptoms like this before in my 200 in moist weather due to
>> failing ca5Bp/wires and from bad gas.
>>
>
> snip
>
> Not sure I get this...MFI? In any case it's not a potentiometer at
> all even though it looks like one. It's actually an idle switch and a
> full throttle switch in one housing. Common voltage supply on one pin
> and signal out for each switch on the other two. If your idle is
> correct at 800 the idle switch is ok and if you see more than 1.1 bar
> than the full throttle switch is ok. The idle switch tells the idle
> controller and ISV to do its thing and the full throttle switch tells
> the ECU to up the boost via the boost control solenoid and enrich the
> mixture via the mixture control solenoid.
>
> In any case, check engine light without storing of code is a
> sustained knock indication. It may be either real knock or a faulty
> knock sensor signal. Consider cleaning knock sensor connector and
> checking that it is torqued down properly. As this is an MC2 you have
> two sensors.
>
> As always refer to http://www.sjmautotechnik.com/trouble_shooting/
> trouble.html
>
> Scott has spent untold hours distilling the various Bentley manuals
> into something that is actually readable and combining it with his
> unparalleled practical troubleshooting experience to produce the one
> stop shop for all things turbo CIS related. Let his pain and
> suffering be your salvation.
>
> Roy Wendell
> erwendell at mac.com
> Too many type 44 tq
> A pair of MR2s