Hi, I am trying to find whats wrong with my 740GL - 1989 (B230F, LH 2.4). Yesterday morning the "Check engine" light turned on and the car started running rich with quite strong and strange (not gas) smell.

I got it home and checked the fault codes:

113 - Fuel trim (lambda control) too lean or rich
213 - Throttle switch full load setting faulty or grounding short
231 - Fuel trim (lambda control) too lean or too rich at part load

The first thing was to check the oxygen sensor. It was stuck at 0.9V (too rich). I tried to make a "small vacuum leak" (as explained in the 700/900 FAQ), but it stayed at 0.9V. Then I made big vacuum leak (pulled the hose between the IAC and the big plastic tube in front of the throttle) - the reading went straight down to 0.1V as it should. I also checked the wire from under the hood to the ECU - OK.

Next - temperature sensor - OK. Wiring to it - OK.

I dont know why code 213 was set. The throttle never went to "full" and the switch is OK.

Later on I turned the engine on again - it was still too rich and it set a new code - 131 - Ignition system RPM signal missing on starting. The FAQ says that the car shouldnt start if thats true, but it started OK?!?

Today I had to drive nearby and the engine died twice when stopping at traffic lights and would not idle after I restarted it. Then I parked for 10-15 min. and when started the car again - the idle was about 1500-2000.

When I reached home there were new fault codes:

131 - Ignition system RPM signal missing on starting (again)
213 - Throttle switch full load setting faulty or grounding short(again)
121 - Faulty signal to/from Air Mass Meter (new)

The only test for AMM in the FAQ is to unplug it and see if the motor runs better. Well, my one run worse so the AMM should be OK.

Later on I tried to unplug/plug all electrical connectors. They all seemed OK - 3 years ago I sealed them with dielectric grease. Then I got even more fault codes:

312 - Signal missing for knock-related fuel enrichment
221 - Fuel trim (lambda control) too lean at part load - !?!
213 - Throttle switch full load setting faulty or grounding short(again)

The idle in Park is still high - about 1000, but in gear is OK and the car doesnt run that rich any more. Now when I clear the fault code memory and start the engine for a few seconds only the "Check engine" light stays off and only 2 codes are set - 312 and 213. If I leave it to idle for about 5 min - the codes change to 213, 221 and 131.

213 seems to be wrong as the TPS tests OK. 131 seems to be wrong as the engine wouldnt start if no RPM signal. The rest... I dont know.

Anyone seen something like that? Any suggestions?

Thanks,
Andrew

P.S. Part of the problem is that I am very short on cash right now. The wife just came out of hospital after spending there over 2 months and I have to stay mostly home to look after her.