MAF OBD1 Code 34

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#1
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MAKE:Buick
MODEL:park Ave
YEAR:1989
MILES:205,000
ENGINE:3.8 V6
DESCRIBE ISSUE....Engine stumbled 2-3 times and died at stop signs and check engine light appeared . My old OBD1 OTC scanner pulled code 34 ( No MAF signal for over 4 seconds while engine was running) It also showed it always running lean (instead of lean- rich- lean-rich as normal).

I cleaned the contacts and MAF with electronic cleaner, but there was no change.

Then I installed a used, but known good MAF from another running car with identical great running engine. I did not want to purchase a new one for trial since they cost $100 or more. Plus known good used is always better than unknown new .

I cleared the code memory, ran the engine, but for the first several minutes the check engine light flashed about once every second and my scanner said NO DATA.

But after several more minutes, perhaps after closed loop ???, everything cleared up and car ran fine and no check engine light and no code 34.

I have never experienced that flashing light situation before. Is that normal or should I be expecting a future problem?
 
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#2
Hey jack - saw your post and I am confused (again), are you sure its a MAF code - I see a MAP code on quick check....

Can we confirm - MAP or MAF? obd1 really challenges my memory
 

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#4
To restate, maybe I am just over thinking the several minute flashing CEL after installing the known good MAF?

Driving for two days, there is no CEL on, no codes and no drive-ability issues. Perhaps just a glitch with my scanner or with the car's ECM or relearning ?

I will have to return the test known good MAF.

On the old original MAF I have cleaned and checked continuity on both miniature wires. but it still throws a code, is there anything else I can do accept purchase a new one? Seems like the problem is internal and therefore not repairable.
 
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#5
going by your information, 34= no MAF signal for @4sec... on 2 different MAF's -
might want to check wiring, could be bad connector at MAF or a bad wire, they often fail within several inches of the connector.
3 wires correspond with 'ABC' on sensor
1 is 12v C
other is ground B (center)
and MAF signal A, is a Hertz signal...

Eng at idle, with a DVOM set to Hz tug wiggle harness to see if Hz reacts.


I do not think there would be freeze frame to help, nor do I think your scanner would show live data from ECM, as you tug shake harness.
As likely that the signal is lost anywhere over length of harness and or ECM connector...
Again my quick check jumped to incorrect trouble tree, tonght I will 'dig' into this need more time to find the OBD1 stuff.

PS: What is 8th character of vin#?
 
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#8
Installed the new Walker MAF sensor and it worked fine the first day. Then on the second day, every time I started the car , hot or cold, it had a minor miss for about 30 seconds or about a block. No CEL comes on.
Third day all seems well. What???

At first I was going to condemn the new part, because the old borrowed known good part I was using gave me no problems for 300 miles and a week of driving.

Is there a "learning period" on OBD1 ? I know there can be on OBD2, but I do not recall that there was one on OBD1.
 

billr

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#9
I would assume there is. If it has long-term fuel trims, those were "learned".
 
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#10
It does have PFI (one injector for each cylinder). Does it have long term fuel trims? I don't know.
I can read Block Learn on my OTC scanner which say the numbers indicate long term adjustments made to the fuel mixture. Since this is way after my formal training, I am not sure what to do with that info.

Just got back from another drive and it runs perfect. Hopefully yesterdays misses was just relearning???
 
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