redraif

Ok I have been thru 3 MAS in 3 days. The car just bagan running like crap. Shuttering and hesitating. finally it coded. MAS. So I have a few spares from the yard hunts. So I swap. It goes bad. I swap again, it goes. The last one was a reman. I was 99% sure it was OK.

Could it be something in the car making them go bad?

Are the 2.8L MAS year specific?

What about cleaning them. What do you use? Electrical parts cleaner?

Please anyone have any idea. I have one MAS left, or its parts store replacement time!

Help!

89camaroRSV6

well i think its MAF..
even though its a MAss Air Flow Sensor
its still called MAF

well ..does the SES light remain on??
if it did ...didya check the codes??
are u sure its the MAF...

i dont think u can clean it with parts cleaner that
sensor will go bad

WaynesRS

You can clean just the little line part with the orange thingy on it . Use a q-tip and put some break cleaner on this . I learned this from GM MECHANIC APPRENTICE . (1991TealRSt-topguy )

Also , when I took my car to the shop because I had it with it , one of the mechanics told me it was another bad MAF sensor . He said he got 3 of them one time in a car before he got a new one .

Unplug your MAF sensor ...How does the car run without it ? run good ? ...Then you have another bad maf sensor .

rezinn

What code are you getting? I'll tell you for sure that if you're constantly replacing the sensor then it isn't the problem. You need to replace the relays and clean the connectors that go to them and make sure the sensor is on tight with no vacuum leaks. I've used throttle body cleaner in the past to clean mine off, but this shouldn't really be necessary if the burnoff is doing its job.

89camaroRSV6

whatever u do ...dont take it close to water...(in ther words dont clean ur engine with a water spray....thats bad)

KED85

Rezinn has it correct
AND
Don't count out Electrical power to the unit
i.e. Alternator.

Nixon1

I had a buddy with a shot MAF..sucker was so dirty. He never replaced it..one day he got fed up and unplugged it. Took him 10 mins to start his car without it. It'd fire up and run for 1-2 seconds and abruptly die...

funstick

are you getting code 33,34 ??? if so check the 02 sensor. if its bad or out of range it will throw a maf code.ive seen more bad 02 sensor than maf's.

89camaroRSV6

thats soo true...

just on the side note...are the MAFs that we have in our car
frequency output / voltage output??

funstick

fq output. it keeps voltage at a steady 2.5. use a multimeter to check for maf fq. in hz. it should be between 26hz for idle to 130hz for wot.

also download this

www.winaldl.webhop.net

its a 160 buad scanner that works with yr ecm. this way you can see what going on in the brain there. also build the simple interface. mine works like a jiffy. select 0n the scanner setup or configuration

1986 2.8 mpfi

1991tealRSt-topGuy

thanx wayne

although i dont remember saying to use a q-tip

ok , here we go:

did you check your MAF grounds?
bad grounds are very common

how about the MAF relay?

the constant hot to the relay goes through a fuse (atleast thats what it says in my schematics diagram) i'm willing to bet its actually a fusible link

check that too


also, lets not ignore another possiblity (although rather uncommon) a fried ECM



given these clues, you should be able to figure out a diagnostic approach

89camaroRSV6

i used one of his eariler versions...

it did not support the 7302 ECM ...but i used to use
the 86 fiero mode that he had...also it worked as a 7747 ECM
but not all values were being logged...

i tried to build a Microchip PIC based system using a LCD
still mostly stuck in the code though...u cant do much with just
35 single word instructions that it offers (16F84)
plus only 1024 words of program memory..(and it doesnt support
sync IO so ill have to write routines for it too)


funstick have u ever burnt some proms for the 177302 Ecm???
can u please email me..i have a couple of questions..

redraif

Man, electronics are not my friend this weekend. Got home and the computer did not want to work with me. I think it was all the rain we had in GA this weekend. My phones get staticy and you can't get a decent internet connnection for crap. That and I lost the whole weekend moving my Scout from one small out of the way town to another. Long story, but it can't stay at my house!

Well we are going to check the voltage tonight. The car is coding for a MAF (don't know why I said MAS earlier, you guys got the point) The car has been coding for a MAF fault and as soon as we unplugged it the car runs perfect. So I'm guessing I just had a butt load of bad MAFs. I have one more. I'm going to check the grounds and fusable links. Recently I had to put in a new computer, so for now I'm going to say its OK.

I think the first one went bad due to a vacuum leak. The seal down the side does not look so good. I will check out the car and if all sems ok, I have one more MAF. I will let you guys know what we find out. There is a good chance I over did it with cleaning the last ones. Seeing as how they were yard MAFs they looked pretty bad inside. So they could have already been bad or I did it cleaning them the wrong way. I have a feeling I did it cleaning. So exactly how should I clean it.

TomP

If you search the V6 forum, you'll find a ton of info, but I'll just repost some of it anyway...

You can do a visual inspection of the MAF's. First visual inspection is somewhat easy, look for any cracks in the tubing (air leaks). Make sure your intake system has no air leaks before or after the MAF sensor. Second, take the MAF out, and look at the orange frequency film. The film should be perfectly FLAT, no ripples, no creases, no bends, no warping, NOTHING. The film vibrates according to frequency... if it's warped, it doesn't vibrate like it should (if at all). Lastly, examine the connector, both on the MAF and on the car's harness, for signs of corrosion.

There are two codes for a MAF, which code are you getting? Hopefully it's code 34, in which case, I'll repost this simple diagnostic chart for you... takes 10 minutes with a multimeter.

-----------------------------------------------
DIAGNOSTIC CHART FOR CODE 34 (2.8L MPFI ENGINE)
---------------------------typed by Tom P------

First off, they want you to check out the air intake duct for being loose or
damaged.

Since you are getting the code 34, and no other error codes, we can kind of jump into
the middle of the chart:

1. Ignition off. Disconnect the MAF sensor wire. Connect a voltmeter between the
____harness pin "B" (center) and ground.
_______Less than 1 volt? Go down to "1A"
_______Over 4 volts? Go down to "2"

____1A: Disconnect ECM A-B connector. Check circuit 528 (brown/white, on connector
_________"B", terminal #6) for an open or short to ground. If it's not open/shorted,
_________it's faulty ECM connector terminal B6 or a bad ECM. By the way, this is the
_________MAF's "signal" wire.



2. Connect a test light between MAF harness pins "A" & "C".
_______Light on? Go down to "2A"
_______Light off? Go down to "3"

___2A: Faulty MAF sensor connection or sensor. So since you've tried two sensors,
________I'd imagine the connector's at fault. Try checking for corrosion on the
________connector's pins- I had that happen once. Also, try wiggling the connector,
________and seeing if you get a SES light. If I wiggle my current one, I can make
________a code 34 set, and the car almost stalls. I've gotta get another connector
________from a junkyard... Pep Boys sells new ones, but for an outrageous price.
---------update 10/2000: I replaced the connector (actually, the whole MAF harness!)
---------with one from a junkyard car. No more connector problems!



3. Connect a test light between MAF harness pin "A" and ground.
_______Light off? Go down to "4"
_______Light on? Go down to "3A"

___3A: The ground wire for your MAF, which is MAF harness pin "C", is open. Fix
________the problem with the black ground wire, either it's bad or burnt thru or
________it broke at the passenger-side-upper-frame-rail grounding point (a ring
________terminal on a screw).



4. Disconnect MAF relay, ignition "on" (not "start"). Connect a test light (at the
____relay connector) between CKT 840 (brown) and ground, and CKT 39 (black/pink) and
____ground.

____Okay, now, the MAF relay is located between your air filter box & radiator, on the
____radiator support, I believe. It should have one long black connector to the harness,
____NOT two connectors (one black and one gray)- that ones for your flip up headlights.
---------update 7/2001: For Camaros, you guys have a different location for your airbox.
---------But, the MAF relay's in the same spot, at the passenger side of the radiator, on
---------the radiator support. I believe it's the only relay you Camaro guys have down
---------there; just check the relay for the wire colors I mentioned for CKTs 840 & 39.


____The test on CKT 840 checks to see if voltage is getting from your MAF fuse to the
____MAF relay.

____As for CKT 39, that's controlled by your GAGE fuse. (So that's what it does! Cool.)
____It comes on with the car's ignition- that's why you need the ignition "on". When this
____black/pink wire gets power, it flips the MAF relay's magnet ON, which basically switches
____the MAF on- that's how power gets from CKT 840 to the MAF.

_______Only one light? "repair the open circuit".
__________No light on CKT 840? See "4A"
__________No light on CKT 39? See "4B"
_______Both circuits are fine? Go see "5"

___4A: If no light on CKT 840, find the MAF fuse- it's under your hood, screwed down
________to the upper-frame-rail on the passenger side of the car, closest to the
________headlights. You'll see two little black boxes, each with two wires coming out
________of them, screwed down to the upper frame rail by one screw each. One of them
________has a red wire and a BROWN wire coming out of it- that's your MAF fuse holder.
________Pop the top off to see the MAF fuse. (The holder with red & orange wires is for
________your computer and fuel pump.)

________If the fuse looks fine, try replacing it anyway... I've had that happen to me-
________the fuse looks fine but's really shot. Perform test #4 again. Still no light?
________Probe the MAF fuse holder's RED wire with a test light to ground. This checks
________the MAF fuse holder's connection to the positive-junction-block, located on the
________passenger side of your radiator support. If it's bad, follow the red wire to
________the junction block & fix it. Do test #4 again- still no light? Check
________for corrosion on the MAF fuse holder's contacts. You should get a light by now-
________unless your test light's shot!

___4B: If no light on CKT 39, check the GAGE fuse in the fusebox. As I said up in "3A",
________if the fuse looks fine, try replacing it anyway. Do test #4 again. If you've
________got no light, you get to trace CKT 39 thru the firewall, so hopefully you get
________a light on this one. This one would be a bitch to fix. All I could tell ya is
________that the black/pink wire goes to the GAGE fuse, and the GAGE fuse gets turned
________on when your ignition switch gets turned to "on".



5: Connect a test light between circuit 840 and CKT 450 (black ground wire from the
____relay connector).
_______Light off? See "5A"
_______Light on? See "6"

___5A: Fix the bad ground wire (open on CKT 450) from the relay to the chassis.
---------update 10/2000: This is buried! It follows the wiring harness along the
---------passenger side lower frame rail. You'll have to trace it the whole way. It
---------joins with 5 or 6 other ground wires at one point. Then, after that junction,
---------one wire goes to a ring terminal on the rear driver's side head.



6. Check out the condition of the orange/black wire that goes from pin "A" of the MAF
____connector to terminal "E" of the relay. If this wire is fine (not shorted or open),
____then your relay's bad... you could get a junkyard one but I think a new one is only
____$10 or so from GM.

LT1guy

iTrader: (1)

I think it was probably the cleaning...I don't remember spraying anything directly on the board when I cleaned your old one (long ago), but rather concentrating on the wire...when you sprayed them down, you pretty much saturated everything, which is most likely where the problem is. The car runs far better with the MAF disconnected, BTW, so we're sure its MAF related. The first one I suspect may have been done in by vibration from the nearly rigid intake plumbing.