Our 1989 244 has occasional no start problems. (cranks, no start) Tonight I checked the computer readout per Bentley's and it showed a code of "3-1-2," which appears on their chart under fuel injection, as "anti-knock signal missing." Then I tried car, started perfectly. Restarted fine several times throughout the evening. I can't find knock-sensor in the Bentley book anywhere. I am checking all connections, replacing fuel pump relay, already replaced the in-line blade fuse with ipd's conversion....may replace the speed sensor on bell-housing if all else fails. So what's the deal with the knock-sensor code??? Tips would be appreciated, thanks, Dennis

Dennis,

I have the same error code on my 89 244 and have had it for 6 months now, I do not believe this is the cause of the no start condition. I haven't bothered diagnosing it because the knock sensor is buried on the engine block drivers side behind the engine breather box. Since the car just passed jersey "enhanced emissions" test and there is no pre-ignition problems i am going to leave well enough alone.

I have diagnosed a no start situation a year or so ago and it turned out to be oxidized pins on my mass air sensor. After a cleanup and electrical grease my no start condition cleared up.

Typically the RPM (hall sensor) will fail after the engine (and sensor) heats up a few minutes. After a cool down time the motor will restart.

Also ckeck the fuel pump relay:

http://brickboard.com/FAQ/700-900/Engine-Fuelinjection1.shtml#Fuel Pump and FI Relay Diagnostic Tests

http://brickboard.com/ARCHIVES/1997SEP/3391.shtml

no start ckeck list:

http://brickboard.com/ARCHIVES/2001MAR/20136231.shtml

Regards,

Dom

Dom:

Thanks for the info. Gives me more to go on. I also doubt the knock sensor is my starting problem. I more expect it to relate to something dirty (your oxidized contacts) as the car sometimes sits 2/3 weeks without going anywhere.....after that is when we have the problem. My wife uses it to go out-of-town to see her parents (coming up soon) and therefore I worry about trouble on the road for her. I think I may put in my new fuel pump relay and keep the original in glove box. Then clean all contacts and read the references you mentioned. Maybe I should worry about the Hall sensor too. Thanks, Dennis