88 chevy 2.8L Mass Airflow Sensor problem?

Crusing in my '88 Chevy 2.8L V6 and all of a sudden car starts bucking, huffing, slows to crawl... won't go over 10 mph.... feels like starvation for gas.
Check Engine Light never comes on... (although it will when I unplug the MAF).
Fuel pump powers up normally.
Car has 91,000, runs like a clock. Never had any trouble for 15,000 mi.
Car starts up, will idle forever, will revv to redline in neutral, but has absolutely NO power when in gear.
Suspect MAF. Car runs the same whether MAF is plugged in or unplugged. No difference.
Heavy Orange 12v MAF supply wire (fed through a relay) has no voltage on it, and infinite resistance (pushed a needle through it to test it). Nothing happens when I apply 12v to it either (naturally since it seems open in both directions).
Two input pins to MAF from ECM have 4v and 6v dc on them. All the rest seem uninterestingly dead. No variable signal on any MAF wire when revving up (of course I can't detect a 50 Hz square wave with an analog voltmeter).
This is one of those AC GM Thin Film type of MAF's.
1. Shouldn't there be 12v on the heavy orange supply wire going into the MAF?
2. Where is the "MAF relay" located that energizes the heavy orange supply wire?
3. Where is the 30 amp "inline" fuse that feeds the heavy orange MAF supply wire located?
4. Is it possible the film burned out and blew the 30 amp fuse at the same time? Why no check engine light if so?
3. Any suggestions: a. Does this sound like a MAF problem? b. Could this be a clogged fuel filter or some other stupid problem... a vacuum failure? I doubt it's ignition problems?
4. MAF's for this car are a dime a dozen in the junkyards, and easy to replace, should I just get one and try it? What about that blown 30amp fuse that's supposed to be energizing the MAF?
not even funny, .... Benny
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Chevy what?
On some vehilces of that era the MAF is there but non-functional. Power to the "Air Flow Meter Relay" has been disconnected.
Steve
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On Tue, 25 Oct 2005 11:37:10 GMT, "Steve Mackie"

sorry .... 88' Chevy Celebrity 2.8 V6 4door sedan with multi port f.i. (w/a.c.)
By the way I replaced the coil pack a year ago with a junkyard coil pack from a '90.... no trouble with that since.

oh for cryiin out louds...!
VIN number is: 1G1AW51W7J627 - - - -
... and the Check Engine Light does come on when I unplug the MAF while the engine is running.... it goes back off when I plug it back in.
this is the fully loaded model.. power windows, power seats, a.c., ... i'm 63 and it's the only car i've ever had with power windows!

Thanks Steve...... looks like big time car trouble .... Benny
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to
There is still a functional component, the Manifold Air Temperature sensor is part of the MAF. That may be why the MIL is coming on. Also, the MAF is still connected to the PCM, it just doesn't receive a signal.
To find out if you vehicle's MAF is functional, you need to know if it has the "speed density update." If you don't have, apparently you should get it. That's all I know, maybe someone else can tell you how to find out if you have this or not. Maybe the dealer will be able to help you with that info
Steve
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On Tue, 25 Oct 2005 17:10:28 GMT, "Steve Mackie"

"MIL"; is that an acronym for the "check engine Light"? What does M-I-L stand for?

Is the "speed density update" an electrical signal? Is this the 50 kc frequency output from the MAF? Or are you talking about whether or not the ECM itself is an updated version that doesn't use the MAF at all... i.e... "functional MAF" vs "non-functional MAF" model years?

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Malfunction Indicator Lamp

This is where this thread gets a little beyond my knowledge of the subject. I pretty sure it's an update to the ECM. A quick Google of "speed density update" says a bit. Any thing else I say on the subject would be merely a guess. I would sugest contacting your local dealer with your VIN and ask about the speed density update; if you have it or if you need it.
Steve
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On Tue, 25 Oct 2005 18:33:39 GMT, "Steve Mackie"

Well.... if the car has been running for 16 years there is obviously no reason to "update the ECM" at this late date.
But I do see what you are talking about... this 2.8 mpfi V6 is a "rare bird" in that it has BOTH a MAP and a MAF (most cars have one or the other).. and apparently GM did "update the ECM" in later model years of this car to eliminate the MAF and just run on the MAP... which of course called for an "updated (prom)" in their ECM. Meanwhile, they just left the MAF in the cars on the production lines, apparently because they still needed the air temperature sensor built into the MAF.
Whether or not my car is an "updated" MAP-only model or an older MAP+MAF model I don't know... and I guess I'll have to find out.... but in any case, I don't see any need to "update" the computer at this point... if the MAF is bad I'll just go to a junk yard and get another one!
But now.... since I find out that the orange supply wire to the MAF is dead..... and the MIL light never came on.... I SUSPECT that my model is a later model where the MAF is simply disconnected...... dunno.... but if the MAF did blow the fuse.... the MIL would be on, wouldn't it?
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My '88 Cavalier Z-24 2.8 MPI had a similar problem a couple years ago; to make a long story short the culprit was the ECM itself (no MIL due to this).
A failing computer causing operational problems can similarly fail at lighting the MIL or displaying codes. These are also well known for the crank sensor connections becoming oil-fouled (happened to mine twice), although it doesn't sound like your symptoms point to that.
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On Wed, 26 Oct 2005 21:41:35 -0500, snipped-for-privacy@webtv.net (James Goforth) wrote:

Na.... the MIL light comes on when I disconnect the MAP sensor, also comes on when I disconnect the MAF sensor, also comes on while engine is cranking like it should.
1. Mackie tells me me the MAF was "bypassed" by GM in the late model years of this car. VIN confirms it is an '89 even tho it is registered as an '88. I now believe the MAF is "bypassed" on this model and the ECM has a new production line prom updating it to the "speed densitiy" (MAP only) theory which GM finally turned to in '90.
2. MAP sensor and TPS check out absolutely ok. In fact the MIL light has NEVER come on, and still isn't on! Therefore, I don't think it is a bad sensor.
3. However it has all signs fuel starvation (starts, revvs fine, but NO power when in gear).. will only go 10 mph, bucking, huffing and stalling and going dead if the throttle is opened.
4. I'm beginning to suspect the fuel pump. Would low fuel pressure turn on the MIL light? (I'm guessing no).
5. Is it easy to check the fuel pressure on an '89 Celebrity?
Benny
PS... thanks for the attention... I'm riding a bicycle again and depressed as hell.... and mad at Detroit. I've had 50 cars since 1960.. and in the old days none of this "hi-tech" funny business even existed. Imagine putting a fuel pump inside a gas tank for cripes sake. Who are they kiddin!
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I'm thinking if the MAF blew a fuse, the MIL would be lit as the input from the sensor then would be out of range once it was in closed loop. Unless the ECM is malfunctioning and hence the MIL as well.
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btw - that supply wire should have +5 volts -- not 12. so the one you're getting 6 volts on is probably your supply wire. however, you should be getting a variable voltage on one of them, but not necessarily when you rev it in neutral - try putting it in gear, hold the brakes down & give it gas & see if any of the readings change. perhaps the diaphram inside it is stuck (would cause bogging for sure)
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Not sure the exact wire you are talking about, but in this case the "ORG" wire to the MAF the OP refered to will have 12V. The signal wire(s) will be as you stated.

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On Thu, 27 Oct 2005 10:23:10 GMT, "Steve Mackie"

Right... the heavy orange input to the MAF comes right from the battery through a 30 amp fuse... apparently it's for heating the thin film resistor in the MAF. I now think you're right... the VIN says this is an '89 not an '88 and it's well known apparently that they updated the ECM's on the production line with a new prom so as to run on "speed density" (MAP only) rather than MAP+MAF which was overkill in the first place. I'm pretty sure the MAF is bypassed on this mjodel except for the air temp. which they stll use, which is why the MIL comes on if I disconnet the MAF.
BTW... this car runs the same (miserably) even if the MAP is disconnected" I'm beginning to suspect the fuel pump.. simply bexcause the MIL light is not on and never has been on.

Na.... the MIL light comes on when I disconnect the MAP sensor, also comes on when I disconnect the MAF sensor, also comes on while engine is cranking like it should.
1. Mackie tells me me the MAF was "bypassed" by GM in the late model years of this car. VIN confirms it is an '89 even tho it is registered as an '88. I now believe the MAF is "bypassed" on this model and the ECM has a new production line prom updating it to the "speed densitiy" (MAP only) theory which GM finally turned to in '90 However there is still an air temp. sensor inside the MAF which is stilll being used, and that's why the MIL light comes on when it's disconnected. Mackie told me all this, I researched it and I think he's correct. That's why the MIL light is not on even tho the orange supply wire (which is connected to the battery thru a fuse) is dead... they simply disconnected it on this model.
2. MAP sensor and TPS check out absolutely ok. In fact the MIL light has NEVER come on, and still isn't on! Therefore, I don't think it is a bad sensor.
3. However it has all signs fuel starvation (starts, revvs fine, but NO power when in gear).. will only go 10 mph, bucking, huffing and stalling and going dead if the throttle is opened.
4. I'm beginning to suspect the fuel pump. Would low fuel pressure turn on the MIL light? (I'm guessing no).
5. Is it easy to check the fuel pressure on an '89 Celebrity?
Benny
PS... thanks for the attention... I'm riding a bicycle again and depressed as hell.... and mad at Detroit. I've had 50 cars since 1960.. and in the old days none of this "hi-tech" funny business even existed. Imagine putting a fuel pump inside a gas tank for cripes sake. Who are they kiddin!
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reset snipped-for-privacy@hotmail-dot-com.no-spam.invalid (superchuckles) wrote:

What diaphragm?
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On Thu, 27 Oct 2005 13:00:32 GMT, aarcuda69062

right... I don't think there are any "diaphrams" in the mass air flow sensor... there certainly are no vacuum lines connected to it.
Benny
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On Thu, 27 Oct 2005 03:15:35 -0500, reset snipped-for-privacy@hotmail-dot-com.no-spam.invalid (superchuckles) wrote:

Na.... the MIL light comes on when I disconnect the MAP sensor, also comes on when I disconnect the MAF sensor, also comes on while engine is cranking like it should.
1. Mackie tells me me the MAF was "bypassed" by GM in the late model years of this car. VIN confirms it is an '89 even tho it is registered as an '88. I now believe the MAF is "bypassed" on this model and the ECM has a new production line prom updating it to the "speed densitiy" (MAP only) theory which GM finally turned to in '90 However there is still an air temp. sensor inside the MAF which is stilll being used, and that's why the MIL light comes on when it's disconnected. Mackie told me all this, I researched it and I think he's correct. That's why the MIL light is not on even tho the orange supply wire (which is connected to the battery thru a fuse) is dead... they simply disconnected it on this model.
2. MAP sensor and TPS check out absolutely ok. In fact the MIL light has NEVER come on, and still isn't on! Therefore, I don't think it is a bad sensor.
3. However it has all signs fuel starvation (starts, revvs fine, but NO power when in gear).. will only go 10 mph, bucking, huffing and stalling and going dead if the throttle is opened.
4. I'm beginning to suspect the fuel pump. Would low fuel pressure turn on the MIL light? (I'm guessing no).
5. Is it easy to check the fuel pressure on an '89 Celebrity?
Benny
PS... thanks for the attention... I'm riding a bicycle again and depressed as hell.... and mad at Detroit. I've had 50 cars since 1960.. and in the old days none of this "hi-tech" funny business even existed. Imagine putting a fuel pump inside a gas tank for cripes sake. Who are they kiddin!
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