Dave M

I'm posting this for a friend:

Does an 89 2.8 have a MAP sensor? He says his engine doesn't have a MAP sensor but he says he's getting codes 33 and 34 which are supposedly MAP high/low codes. I'm not sure why his manual says that what the codes mean if it also says he doesn't have a MAP sensor but can someone shed some light on this problem? What are codes 33 and 34 on an 89 2.8, and if they are MAP high/low where is his MAP sensor?

Derickab

For 89 and earlier V6 MPFI the codes can be for the MAF sensor ( also for the TPI V8's). You are correct though there is no MAP sensor on 89 and earlier V6 and 8's only after those years. This info is straight out of the Haynes book 82-92.

Hope this helps.

V6sucker

look at the intake tract... is there a black plastic tube roughly 4" long with a 1-1.5" plug with 4? I think wires?

If so then he is MAF. But the year alone says it is MAF. But a 90-up SD (Speed densisty) system could have been swapped in.

Project: 85 2.8 bird

the 2.8s don't have a true map sensor, though it sure's hell looks like one. IT's called by a different name, baro swirtch or something like that

bru333

What manual is he using? Some of them aren't exactly accurate.

Code 33 and 34 are used interchangeably between MAF and MAP, since you only have one or the other never both.

As was stated earlier an '89 should have a MAF unless someone swapped in a SD system from a '90 and up.

From GM manual:
33 MAF high gm/sec
34 MAF low gm/sec


MAF sensor:

xplane

hey in that pic you have a big MAF that is the same size as the intake tubing is that a different than stock one? mine squeezes down to about 1 1/2 in across at the MAF.

Project: 85 2.8 bird

that's stock size. Are yo sure you didn't have a fwd one slapped on?

xplane

well i did not do it but my car always has run much better with the intake hose off of the plenum mabe that has some thing to do with it. i just figured it was cause i have crappy cheap filters.

bru333

Sounds like someone put a FWD MAF on. They are a bit cheaper (about half price) than the ones for our cars, so that is prolly why they did it.

fwd maf:

xplane

ya thats it will i get any better performance/ fuel economy if i install the correct one? or should i just not worry about it? it looks to me that there is an very large amout of air flow being blockedcompared to the stock one. also would having the wrong one be the cause of my ECU burning the fan chip? i really dont think so but i will ask any way. another thing how much can i expect to pay for a new proper one?

xplane

another question. i have noticed that the car seems to start loosing power at about 3500rpms i have heard that this is where our engines are in their powerband if so wouldnt the engine still be holding strong for a bit more? i try not to run the car that hard but that is where the trans shifts at even at really light throttle. at WOT it shifts at about 4500 or even as high as 5000. talk about pissing every body off they all think that im holding the trans from shifting just to tick them off. got the cops called on my by an old lady that lives next door and the cop wouldnt believe me till i took him for a ride.

TomP

Dave M, your friend isn't using a Haynes or a Chilton to do diagnostic, is he??? STOP and buy the real shop manual for that car from http://www.helminc.com !! I never use my Haynes for diagnostic. Haynes is good for dropping a gas tank or rebuilding a suspension- but NOT diagnostics or wiring diagrams!!!

Xplane, your tranny won't shift below 3500 rpm? Start saving $$ for a new transmission. You're like me, with a pre-87 transmission, and your fluid pump is probably slowly failing. Your TV cable is also probably way out of adjustment- but if you put it to the proper setting, I bet you'd kill the trans even faster. (When a trans runs at the wrong TV setting for too long, it wears out, and then can't handle the correct pressure ever again.) Trust me, start saving money- I'm on my third transmission.

xplane

well the trans was suposedly rebuilt with all new internals by my sisters boyfriend about a month before i got it so mabe he just didnt put the cable back properly.

xplane

hey i went through and checked all my connections and found that my MAF was not all the way pluged in now it says i have a code 34 and acording to the FAQ it means high vacume at MAF so caould the smaller size be the cause? smaller diameter = less space for air to get through? also is it normal that when i tap the throttle that the line from the MAF to the intale will draw in on its self? i noticed that mine does that a lot