i got a check engine code but that could be related to alot of things so before i go just throwing money away i want to know what exactly happens when my MAF is going bad.....

BTW my air filter is dirty, would that effect anything as far as a check engine code indicateing maf?

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1989 pontiac firebird
bright red exterior(just repainted)
grey interior
5 spd
305 TBI (stock)
WS.6 formula wheels
3.73 posi rear end
http://members.aol.com/j007golden/Mikey89.html
http://www.geocities.com/firebird/myfirebird.html
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1985 trans am
factory bright yellow
4 wheel disks
16 inch wheels
305 TPI
power antenna and mirrors
t tops

 

First off inspect the hot wire in the tube to make sure it's not visibly broken.

Then with it hooked up, check your voltage at the green wire and ground. You should have about .5v at idle and 5v at wot.

If it's 5v at idle(code 33), either the sensor is bad, the maf power relay is bad, or the connection at the maf is bad.

Swap the maf power and burn off relays and see if you get a code 36 instead of 33, then you know it's the relay.

Check the plug. Even though mine looked ok, the socket expanded out and wasn't making contact with the sensor, setting the 33 and only after buying another maf I figured this out...

The computer sends out a 5v reference which the sensor 'pulls down to ground' at idle. An open in the green wire anywhere will set the 33.

If you do have 5v at idle, and swapped the relays with no luck, you will need to start checking all the wires at the sensor. Check (ohms) both the black and black with white stripe wires to ground. They should have continuity (0 ohms). Check the maf power wire for 12v.

After doing these checks and still have:

- Ground on both black and black w/ white stripe
- 12v on the maf power wire
- 5v on the green wire
- Plug is making good contact

The maf is pretty much toast.

The only other wire is the burn off ckt and since you have no code 36 you don't need to check this, but this could be done by probing a test light between the burn off wire and ground. Running the car for a while (needs to go closed loop and timers must run out) and shut the car off. After about 3 seconds you will hear the 'click-click' and the light should flash for about 1-2 secs.

Hope this helps you... MAF troubleshooting isn't much fun, but it isn't very difficult. A good book with schematics will help...

 

that was quite alot of info . I dont know if i already said this but i got a code for a bad O2 sensor too so tomorrow o will check the MAF as u said above and get my new oil pressure sending unit and my new O2sensor. Ill keep u updated as to how it goes.....

 

quiick test for you wiithout having to dissasemble anything when the engine is at operating temp let it idle lightly rap the housing of the maf sensor if the engine stumbles or stalls goodbye maf reset the computer first before testing

 

Actually, since he has an 85, he does not have a MAF power relay. All power for the MAF is controlled by the burnoff module red wire, I believe it's terminal "D".


Like I said.... he has no relays

That very well could be the cause... mine was freaking out for two years until I replaced that plug. I had to keep cleaning the contacts about every month or so. When it wasn't bad contacts it was the burnoff module so I switched over to the 86-89 "165" setup.

That's not true... like I said, my burnoff module (piggybacked to the ECM) kept giving me a code 33 until last July when I made the switch..... not a problem since I went to the 165 ECM and relays.



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Kevin Irving
85 Trans Am WS-6, 305 TPI, custom burned '86 PROM with '87 "165"ECM, Accel Supercoil & 8.8 Wires, MSD 6AL, Aluminum Driveshaft, Wonderbar, TB Coolant Bypass, Ported Plenum, Modified MAF, Syclone Fuel Pump, JET Airfoil

15.556 @ 86.65mph, Nov 10, 2000.... I know it sucks.. but it will get better!

http://www.geocities.com/transam85tpi/

Member - The Tidewater Trans Am Club, Norfolk VA http://www.geocities.com/ttacva/

 

Good points.... I forgot about the 85's and the stange setup they had...

 

well i replaced my O2 sensor and my oil pressure sending unit but i still get a MAF code 34 so tomorrow ill order my new MAF from autozone. The O2 sensor and oil pressure sending unit are both in and working fine, no more codes fom them....

 

Ouch....buying a new MAF! I feel your pain, I bought a new one last year! They aren't cheap in comparison to other parts on our cars!

About the tapping on the MAF housing to tell if it's bad....that doesn't always work! My '86 TA had a bad MAF and the engine didn't stumble or die when I tapped on the MAF housing!! Also, I can unhook my MAF and the engine will still run fine but I have a continual SES light!! Don't know about high RPMs with the MAF unhooked though! I imagine that is where I'd run into problems with running no MAF!!

 

[This message has been edited by Ken88GTA (edited April 26, 2001).]

 

Hey ONEFINE8T9,

You might want to consider the Wells SU-145 MAF. It's half the cost, flows a little better, and a more reliable design. Iv'e had mine 6 months without any problems.

Ken

 

ken88gta what is the wells145 MAF?? is it a direct OEM replacement just maybe higher flow?? i heard of some people switching to the later model MAF sensors and i really didnt want to go through the hassle of doing that. If im stuck paying 150$ than i guess thats what i gotta do

 

The Bosch MAF is about $500 from GM, at least that's how much I paid for it about 3 years ago before I knew there were aftermarket and reman ones. You can get the Wells MAF which flows better (about 700 cfm) from World Discount Auto for about $160, I don't have the number on me now but I've posted it before... do a search of this board for either "Wells" or my name and it'll come up.

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Kevin Irving
85 Trans Am WS-6, 305 TPI, custom burned '86 PROM with '87 "165"ECM, Accel Supercoil & 8.8 Wires, MSD 6AL, Aluminum Driveshaft, Wonderbar, TB Coolant Bypass, Ported Plenum, Modified MAF, Syclone Fuel Pump, JET Airfoil

15.556 @ 86.65mph, Nov 10, 2000.... I know it sucks.. but it will get better!

http://www.geocities.com/transam85tpi/

Member - The Tidewater Trans Am Club, Norfolk VA http://www.geocities.com/ttacva/

 

Get friggin real! I got a regular hot wire, remanned by bosche MAF at the local parts store for less than $110 after tax.

So I guess I'll be in business selling mafs online at this price? Want one?

 

That's about what I paid for mine Joel! I feel sorry for the guys paying $160-$170 or even $500 for that matter!!