NHRATA01

My '89 is throwing codes 13, 34, and 44. 2 of these are lean O2 readings at idle and cruise that I attribute to an exhaust leak at the passanger side manifold. The other code is for the MAF or MAP reading. Now, last winter the original MAF crapped out on me and the car would barely run and threw the MAF code. Replaced MAF, and car ran fine again, and still runs fine now. So my question is, do MAF cars have a MAP sensor, or do only the speed density cars have it? If they do where the heck is it? Also is it likely the MAF reading code could be set off because of the O2 sensor codes? I'm pretty certain the MAF isn't bad, but puzzled why I still have the MAF/MAP code. Thanks for the help.

RBob

iTrader: (1)

MAF third gen f-body's only have a MAF, no map.

RBob.

Project: 85 2.8 bird

MAP sensor for 85 FIrebird,
from Autozone:

Wells SU135 $47.99
AC Delco 213-185


Car also has MAF sensor.
edit: same info for 89 yr.

RBob

iTrader: (1)

They may list it but it doesn't mean it has one. Does your '85 actually have one?

My earlier statement is not entirely correct as the TTA uses a MAP sensor for the boost gauge. Not connected to the ECM so no you won't see a code for it either.

RBob.

NHRATA01

Yeah I saw autozone and GM Partsdirect listed a MAP sensor, but I thought that was for the TPI cars. I'm still not sure that the MAF MPFI V6 cars have them. Confusing...

Project: 85 2.8 bird

yeah, it's there by the coil bracket

RBob

iTrader: (1)

Wow, learn something new every day. Thanks,

RBob.

1991tealRSt-topGuy

RBob-

i believe that all OBD-I cars had some sort of a MAP sensor, whether it was carbed, TBI, or MPFI

i recall pulling one off of my 87 LG4

ALTHOUGH

they had a different name before 1990, it was something like barometric differential sensor or something to that effect

thunder69n

I am getting code 34, I replace maf sensor before in past for a waste of money.
Noticed in chiltons manuel for my 87 v6 2.8 says the code is refering to
Map Volts low/Vac HI

Maverick H1L

iTrader: (8)

Another long dead post risen again...

There is no MAP on an MPFI 87 year car... At least, not that I have seen, and my car is literally down to a long block with transmission and front suspension.

Code 34 may also indicate a vacuum leak, as the MAF is reading low air flow, or that either the power relay is bad or the power fuse has blown.

TomP

Agreed (although I don't think low vacuum is a cause- this is the reading from the frequency film vibrating)- none on '86 2.8 either- and no 85-89 has one. Only thing that would be on the coil bracket is the EGR solenoid and vacuum switch.

thunder69n

guess what was confusing me is in my book says for my engine that its either map sensor for Vin 1 or its Maf Sensor for vin 5

There is no 5 in my vin. Doesn't say wich digit this is coming from.

At http://www.troublecodes.net/GM/86-89_28S_mfi.shtml Says using the 8th digit mine would be vin S and under there code list says Maf

eseibel67

I just checked the engine control diagram for an 89 2.8l. No MAP sensor.

The VIN # they are asking for is the engine code - always the 8th digit in the VIN.

eseibel67

Your engine code is S. Maybe a typing error thinks it's a 5.

thunder69n

ok cool, yeah prolly just a bad typo in my book

thunder69n

Can't seem to find the thread that I found a posted link to the diagnostic flow chart for the mass air flow sensor. As far as code 34.

Testing in step 3 between terminal B of the disconected harness and ground wire I read just over 5 volts.
step 4 I hooked up a test light between terminal A and C and the light comes on. chart says if light on then Faulty MAF Sensor connection or Sensor. ( scicne this is tested with sensor disconected, power on, can't tell me if sensor good or not. Had replaced sensor previously and belive original to also be good.

But if light comes on between terminal A and C of the connector but I still get the 5v refrence from the ECM. What does this tell me? Does it mean the ground is broken? and direction form here will be helpful.

Terminal A is orange going through a relay/fuse/Battery. And Terminal C looks to be a ground. With light turning on between them. What does it tell me? That the wire from the battery and through fuse/relay is good? And is the ground suposed to stop the circuit? is that why the test light is not suposed to come on?

Maverick H1L

iTrader: (8)

First, the test light is SUPPOSED to light with a test light connected between terminals A and C of the MAF sensor connector. You're probing between power and ground, so it's obvious what will happen.
Second, a test light isn't going to help you much with the diagnosis beyond this point as you've proven the sensor has power and ground. You need a multimeter or scope that will measure frequency.

Check that the terminals in the MAF connector are making contact with the MAF terminals. Again, check for vacuum leaks and leaks in the air intake between the TB and the MAF. You can tap on the MAF with the engine running with the handle of a screwdriver right on the board housing in the side of the sensor. If the engine stumbles, the MAF needs to be replaced. Remove the MAF and examine the orange film inside as well. If the film isn't completely flat, you need a new MAF.

thunder69n

Ok thanks Maverick H1L, I got a multimeter just a nub to the electrical side and how to use it. How I go about checking the frequency?

I had previously checked terminal B of the harnes settign multimeter to 20 dcv read 5.3v coming from there. I had tempted to run a wire touching terminal B when Maf was conected. With engine at itle, multimeter still set to volts, the volts were very speratic from .01 to about 4 volts mostly jumping in the 1-3v range. Is there another way to measure the frequency, and when i do what ranges should I see?
(currently if maf plugged in car shuts off after engine turns over, if unplugged car starts fine.)

Pulled maf off, made sure no obstructions, out of electric cleaner so just blew compressed air to remove particles. made sure I was getting plenty airflow connecting to my throttle body. Seen somthing previously on here about testing the vacuum in gh of the manifold, I plugged in my hand vacuum pump and gauge to a hose in from of charcoal canister that runs to my manifold. at idle it moved between 15 and 16gh, open throttle and the vacuum would drop release throttle and vacuum jumps to 20 but back to 15-16gh

playing with maf sensor off the car I noticed continuity between ground a power terminals but thats way its suposed to be when put multimeter between the two correct.

Maverick H1L

iTrader: (8)

Standard DMMs don't generally measure frequency. When my old DMM crapped out (IDK why), I went out and bought a Craftsman 400A AC/DC clamp DMM that also measures temperature (approximately $100). However, the "plug in and die and unplug and run" probably means you need a new MAF. Like I said before, look at the film inside... Needs to be flat for the MAF to work right. If you have a Bird, I have a 3-month old GM MAF I'm looking to get rid of. I don't recommend aftermarket MAF sensors... I've had 2 different ones that each lasted only a year a piece (and at $80 a pop they will get expensive quick).

thunder69n

yeah this one I replaced in August, its remanufactured. film looks flat. When i was done playing with maf, plugged her back in car started but still the light. Blah bad timing for it to act up again. got inspection next month and my speedometer just went wack recently, guessing speed sensor scince it has no cable. also gotta replace drivers side floor in that time. Guess nowadays an old 3rd gen wasn't the best idea for a day to day driver but hey i love em. Car drove sweet when I got it almost a yr ago now, and has almost 200k coming up and seems its magic number for everything to fall apart lol.

I seen that theres vacuum hose that still needs to be replaced on my break servo, but not sure if that would be effecting the air intake.
Ive been running around with my charcoal canister unplugged, couse she used to do the rpm sure on start. and one time finally got her to stop after replacing list of sensors and stuff.

When this MAF code and problems showed up this time , I had just got done messing with my exaughst, becouse were a clamp was conected in front of my cat that the metel it was holding broke off, so I adjusted it got clamp on and sound comes goes nicly through my cat again. But right after MAF code started acting up.

Random coninsidences and potential issues Parts definitly add up when ur throwing them at her.

thunder69n

Didn't think they would, but I called O'riellys, place I get my parts through, and is a 1 yr warrenty on the MAF sensor I got in August, so going to replace it tommorow, least even if it doesnt work hopefully helps rule out bad maf sensor, worse senerio, best senerio, she runs again, and i can get back to spending money on other things that need before inspection

Will replace couple servo hoses while I am at it tommorow. and then use me new handy dandy hand vacuum pump to bleed any leftover air in my breaks. Guessing when u press the brake, the res not suposed to splash around. ( had to replace brake line form frint to back and never was able to get brakes bleeded on my own.

On the 85 by the ignition coil, is it actually a different part of the vacuum system instead of a map, thought for sure this was the map on mine but was so confused with it being electrically conected to somthing else that doesnt come with the map sensors. still has a vacuum tube and electric plug similar to the map sensor. My hood diagram called it a vac switch, and thing conected to was a vac regulator

86ttopbird

That is the EGR vacuum solenoid. Very pricey bugger too at around $195 a piece. There is no MAP sensor on these cars unless you have converted it to speed density or its a 90's model.

thunder69n

replaced MAF and mine fixed btw