200tq check engine light, but no codes!?

[Ivan Tuma]

Hello All ...

Just trying to see if anyone has had similar problems.

On my '90 200tqw 10v ... I have intermittently felt the engine hesitate 
drastically under load. Last year, I had replaced knock sensor #2 based 
on having the error codes read with an analyser at my mechanics shop ... 
this seemed to help performance temporarily.

I recently put in the "missing" check engine light bulb into the cluster 
so I could flash out error codes on it myself.
I have noticed that after the car warms up a little, the check engine 
light always comes on at ~3000 rmp corresponding precisely with the 
occasional hesitation. It stays on regardless of engine load as long as 
I stay above 3000rpm.  

If I try to flash out error codes, all I ever get is 4444 (no error) ... 
even after I reset the flash (temporary pull of fuse #21) and a week of 
driving. Is my assumption correct that knock sensor #1 is now starting 
to go bad, just not bad enough to report a permenent error to the ECU? I 
was expecting to see any of the following codes: 2141, 2142,2143 or 
2144, but so far none of these has shown up ... I did have some old 
codes in there dealing with previose trouble (these I wiped out), FYI 
they were  2123, 2312, 2214 and 2224 (none of these are related to knock 
sensor problems however).

The SMJ Autotechnik website (noted in the FAQ) is a God-send for 
learning how to pull the codes. Also extremely helpfull is the 
carsoftware.com site for actually interpreting them without owning a 
Bentley.

http://www.sjmautotechnik.com/10vtecu.htm
http://www.carsoftwares.com/audicode.html

Tschus,

Hans.