Could a bad MAF cause poor idle in cold weather and open loop? Could it cause the engine to stall under sudden deceleration? Could it cause flooding? I have pulled a code 34 before. Any other ways of knowing if the MAF is bad? I cant disconnect when the engine is running cause the alternator is in the way and I can't reach the wires.
Will a '86 Maf work with a '85?

thanks
Matt

 

Try disconnecting it and then start the car. If the problem is the same or worse you can probably rule out the MAF. Could also be the MAS module, it is piggybacked on the ECM and controls MAF power and burn-off functions.
Yes an '86 MAF will work on the 85.

 

Before replacing the MAF try replacing both relays. One is the MAF power and the other controls MAF burnoff which essentially is a cleaning function for the MAF unit. They are the same part #, NAPA# is AR-279. Its very common for these relays to cause intermittent operation of the MAF. Sometimes when its idleing you can tap the top of the relays with the handle of a screwdriver and notice the engine stumble. I guarantee if one is bad the other one will be intermittent also. The MAF sensor is actually very reliable as long as it is not struck or dropped, and you DON'T want to buy one if you can help it.

 

He is running an 85 ECM setup, he doesn't have the relays, he has the MAS module.

 

When I upgrade my ECM to the '86-'89 versions does the MAS get replaced by the relays or do I still retain it?

Need these answered:
Is there any physical way of seeeing if the MAF is bad?
Would a bad MAF cause a bad cold idle AND a bad idle in open loop?
Could a bad MAF cause stalling after deceleration?
What other symptoms of a bad MAF are there?

Thanks

Matt

 

Yes, the MAS module gets replaced by 2 relays when swapping to the 165 ECM.
Other than the obvious broken heated wire...not really, no.
No, in open loop the ECM ignores all sensors except the coolant temp sensor, looking for the temp to enter closed loop
Yes. But then again several things can cause that too.
Belching black smoke and then dieing as soon as you take your foot off the gas, poor performance, high fuel consumption, hesitation,.....the list goes on and on, and sometimes it will set a check engine light and other times it won't.

 

Morley,

Not to question you, but I was under the understanding that the early '85 TPI engines used a Delco/Rochester digital (FM output) MAF and the '86-'89 TPIs used the Bosch analog output MAF. Am I confused or what?

 

The MAF that came in the car when new was a Bosch unit....was replaced when 2 weeks old (water ingestion) with another Bosch unit that I am still using on the same car.

I'm using my 85 MAF in an 870 system converted to 165 and running a modified ARAP code, seems to work exceptionally well and the scanner software reads what you'd expect to see during operation. No codes set, ever with this setup.

P.S. I ordered the car in Feb 1985 and was delivered in May 85, so that is about as early as the TPI's get.