My 89 L98 engine shows a 33 code soon after start up. Using the
factory trouble shooting procedure there is no problem found.
replacing the maf with a known good one after erasing the 33 code still results in a 33 code and putting my maf sensor in the doner car does not cause a code. The sensor output wire is continous to the ecm pin. . the dc voltage to the ecm pin stays at 5.0 volts regardless of rpm. Does this point to a problem in the
ecm box or the eeprom?

 

Have you checked the TPS and the air duct for the MAF sensor? What kind of air filter system are you running?

 

I haven't checked the TPI recently. Using open k&m 3 inch diameter filter. No air leaks after maf sensor.

 

Sorry, I meant the TPS. I will check it this friday or before.

 

The code 33 would be set if there was too much air going into the MAF sensor at start up or soon after.

 

My code 33 was driving me crazy. Long story short, correctly setting the TPS (mine was at 3.5 @ WOT instead of above 4) solved the problem. Haven't set the code in months. Good luck.

Kevin

 

Could be your MAF relay. With your car off, remove the ducting to the MAF sensor (but leave the MAF wiring harness connected) and look at the heating element/wire inside the MAF. If it's glowing your relay is bad and this can set a code 33. I had this happen to me, drove me nuts....and a new MAF realy fixed the problem! Good luck.

 

Check out these posts, it may help you some:

https://www.thirdgen.org/techbb2/sho...hreadid=267568

 

Thanks guys for all of your recommendations. It turned out to be the ecm.