This is going to be fairly long but it may help someone. About five years ago my Vette quit while driving home one day, I had the good fortune to call Jay at Vette2Vette while Gordon Killebrew was visiting there. He (GK) told me I needed a new MAF. He also told me to get one for a newer model Vette. I got a reman Bosch from NAPA and installed it. The car was up and running again but I started having idle problems right away. Hunting idle, rich exhaust and less than crisp throttle response. Over the past five years I have posted many times on this idle problem and got lots of good advice. I found some vacuum leaks which made things better when I fixed them but the car was still not right. I changed the IAC, TPS, and every sensor I could find to no avail. Fast forward to last week, I was pulling the car into the garage when I noticed the dash lights flickering, bad regulator in the alt. I changed the reg. and the car ran like sour owl **** when I got done. I did the min. air idle process again and it was better but nowhere's near right. I couldn't figure why the extra charging from the alt would mess up the idle. Then I started trying to help forum member cwyates4 with his problems. At this point I want to thank anesthes, hooblyboobly, & calderone, for disagreeing with me about the '85 MAf being all by itself. I knew better but these guys put enough doubt into my head that I decided to see if Jay at Vette2Vette had a good '85 MAF. He said he had one but he had sold it to someone and they claimed it was bad for some reason so Jay refunded his money and got the MAF back. I asked him if I could just try it anyway, that is when he told me it wasn't an
'85 but an '86 but that it would work. He let me try it just to see if it was really a bad unit. Not only was it a good unit but it solved all my problems instantly. I now have a car that will idle normally, has a nice crisp throttle response and doesn't run me out of the garage from being too rich. Naturally I bought the MAF from him, the NAPA reman is in the can, the darn thing never was right but I never saw a trouble code through all this. I can only guess that the higher charging rate of the alt. affected the way the MAF was working. ??? If anyone can shed some light on this please do
I'm sorry this so long but if it helps anyone it will be worth the time it takes to read.

 

Wow...thats interesting. Maybe you were getting too much voltage at the MAF and it roasted it??? I know that both of the MAF I've tried on my car are good. When I put a bad one on it from my trans am...it made the condition much worse, car would not run at all.

So we know now that the 86-89 Maf sensors work on the '85, but stay away from napa reman. units!

Glad to hear your running good now, problem sounds exactly like mine. Hopefully I'll be giving a report like this in a week or so.


BTW, got that Burn off module for $13.

 

I need to thank you too, if I hadn't started trying to help you I would have never found the problem. I can't believe you got that BOM for $13 congrats on that! I don't think there was too much voltage because I always keep an eye on the gauge plus the problem existed for over five years, it was just a bad MAF to start with. I don't want to bash NAPA, I would go get another one there if need be. Bad units can turn up anywhere.
I want to hear a similar success story from you soon.

 

For a Couple of years I ran one of the Adjustable aftermarket MAF's on mine. Amazing what a difference you could make just by turning that little screw....

Long story - but I finally threw the thing away. More trouble than it was worth. I Think, maybe, that the air temperature compensation in the thing was goofy - or not there at all. I could adjust it so that the car ran well with Cold air temps (as in Winter), and it would become very lean with the arrival of warmer weather. OR I could have it working well during warm temps (summer), and it would become ridiculously rich as the air temps fell getting into Fall.

This was OK as a Seasonal thing, but try driving the car to Florida in February (From Vermont)!

Anyhow - you could See the issues with the MAF output when datalogging (or with a scan tool) - the numbers just wouldn't be where they Ought to for the RPM and load. After a while you get used to what the particular mechanical combination does - what the Air flow readings ought to be at a given idle speed, for example.

I think I about wore Out the little adjustable potentiometer on the thing chasing the adjustment around. Finally it just got to be more hassle than it was worth - into the trash can it went. Might be a fine idea for a Track car, but not something street driven...

Does point out (the Moral of the story..) how important the MAF reading is. Not just that the MAF is Working, but how Accurate is it. Of course you can always "tune" around whatever the MAF you have is showing - adjust the conversion Tables in the PROM. It's not Supposed to be that complicated, however.

 

Amazing, I recall reading that the 86-89 can use a 85 MAF but the 85 can not use the 86-89 MAF, not sure why.

I changed my ECM from the 870 to the 165 and I wonder if this still holds true.

 

Amazing is correct, if I had even thought that I had a defective MAF or that the '85 would not accept the 86-89 MAF I would have taken the MAF back to NAPA right after I installed it but I kept thinking I had other problems. My scans showed some discrepancys but no one knew why.


I really don't know but I would imagine that any year MAF would be compatible with the new ECM.

 

I never risked it and got the '85 MAF, yes the '86 MAF worked on mine too but I've heard they send different signals (one analog and one digital) but I think that may be refering to the later ones used on the LT1 because I never saw a difference. Either way my problem was directly related to the Burnoff computer and not the MAF on my '85. You can wire up two relays in place of the computer but you have to swap the ECM for a '86-'89 and do some rewiring. I ended up fixing my MAF computer though so if it aint broke dont fix it