gm91vette

Have an 87 with TPI system. SES light is on and is indicating a MAP sensor problem (Codes #33 and #36). However, this engine is also equipped with a MAF sensor. From what I can determine from the literature, this engine should not have a MAP sensor and I don't find one. Engine runs great, but not sure what do do about the SES light.

Thanks for any suggestions you might have.

GREGGPENN

Codes 33 and 36 both pertain to the MAF. 33 is high voltage...the other is saying you have a problem with a burnoff relay.

Replace your relays (cheap) and clean the 4-prone plug behind the MAF. See if that cures your problems. (IIRC, the relays sit behind the battery.)

AGENT 86

Clear the codes and see if they come back.


http://members.shaw.ca/corvette86/Code%2033.pdf

http://members.shaw.ca/corvette86/Code%2036.pdf

gm91vette

Followed your suggestions, i.e., cleaned the 4-prong plug behind the MAF, and replaced the 2 burn-off relays, but the two codes (#33 and #36) keep coming back. Also, in what may or may not be a related problem, the engine is becoming more and more difficult to start, although it runs fine after starting. Have replaced the fuel filter and checked fuel pump pressure and both are OK. If I squirt a little fuel into the boot just ahead of the throttle body, the engine will start immediately. Is it possible I have a defective cold start switch or cold start valve?

And thanks for your suggestions to date