200tq check engine light, but no codes!?

[Ivan Tuma]

Hey Ti,

Well ... tried your technique today ... and sure enough I did get an 
error code to flash out. It's 2113 which indicates a problem with the 
Hall Sender.

The MAC-14 computer on the '90 200tq model DOES have permanent fault 
memory, but I don't know why this fault wasn't registering before.
http://www.sjmautotechnik.com/ecuf_MC2.html#fctwo

The system isn't exactly foolproof, and I'm still not trusting the 
results. It still behaves much like a knock sensor problem vs. a Hall 
Sender unit. I'll probably have to buy KS #1 to prove this to myself.

 1. The check engine light doesn't come on until the engine reaches a 
certain temperature (knock sensor system doesn't come online until 
engine is at ~178 deg. F.)
 2. The light only comes on past 3000 rpm (knock sensor data isn't 
analysed until engine reaches over 3000 rpm when it is under actual boost)
 3. The hesitation, when present, is very much like the timing being 
severly retarded.

Thanks for your advice though... at least I got it to give me something 
... just don't know how accurate it is on a 15 year old car. Maybe I 
should reset the FLASH and
power cycle the computer using the battery terminals and try again.

Ivan