djf85vette

After much frustration (and countless trips to the parts store) I now know the cause of my problem (well my cars problem anyway). I have attached a prior post below so you can get an idea of what I have gone through. I finally gave up and took the car to my friendly (and expensive) local Chevy dealer. After much diagnosis work, they informed me that the MAF burn-off sensor has an intermittent failure. They then told me how much it was going to cost for them to fix it .

I decided I would try it myself. Is it difficult to change? What do I need to know? I'd appeciate any advice you can give.

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I have a 1985 vette that I bought about a year and a half ago. It didn't run when I bought and I was told that it had some problems when he had last drove it (it sat for about a year before I bought it).

The first problem I found was a huge vacuum leak at the runner to intake manifold gasket (It had a lingenfelter superram plenum and runner with a 58mm throttle body). Basically I am just looking for stock performance so I removed the lingenfelter and replaced it with the stock plenum and runners.

It still didn't run very well so I asked some folks what I should try next. I was told that the 58mm throttle body was overkill for the stock plenum so I replaced it with a stock TB. It seemed to run better but still had a problem.

The problem is that at low RPM it will not idle smoothly and when I apply a little gas pedal it will bog and sometimes stall. I figured it was either a fuel problem or a spark problem. I set out to replace each component of both until I solved the problem. I replaced everything (plugs, wires, cap, rotor, coil, ignition module, fuel pump, fuel filter, fuel pressure regulator, EGR valve, TPS, etc.).

The problem is still there. One thing I noticed was that everytime I replaced something, the car would run good for a while. I then figured out that the problem could be corrected by disconnecting the negative battery cable. I then assumed that the problem was with the ECM. I replaced that but the problem still exists.

When I disconnect and then reconnect the battery, the problem seems to clear itself and the car runs great until I shut it off and restart it at a later time when it again will not run at low RPM. Any guess what it is?

86VX1

replacing the maff relays is easy, the one inside the cockpit by the passanger side is a pain to get to. The one in the engine compartment is also easy. If you want to test them before you buy them, switch the fuel pump relay in place of either one and see if your getting fuel to the rail, if you are then the relay is good. if you don't then the relay is bad. But if the guys at the dealership told you it is intermittent then you should probably replace them anyway along with maff. good luck. I'll check in to see how it went.

Bluevette85

85's have a Burnoff module behind the breadbox.

goldeneye_vet

Yep! Just a burn off module that is very expensive, time consuming to replace and a bear to get to.

Morley

Are you sure they said the MAS module was bad? If you are absolutely sure that is the problem, PM me, I have 3 of those little gems...GM wants almost $800 for one.

rons85

IF it's really the module (and in my experience they are about as reliable as the Frame...) NAPA has them (at shop price) for about half of the price at a GM store. Same Bosch part in the same Bosch box. Before I condemmed the module I would be taking a real hard look at the wiring and connectors, and the MAF itself.

djf85vette

I asked the mechanic at the Chevy dealer if he was sure and he said he was positive. I have to believe him because I've changed everything else (including the MAF twice!!).

As far as reliability, I've been doing some surfing on the web and found out that this has been a troublesome part for a number of owners. Here is a quote from one website I looked at:

"NOTE: 1985 MAF systems used a MAF Burnoff module in conjuntion w/ the ECM and were very unreliable, and should be avoided."

I did check with NAPA and they quoted me around $350 for the part.

MrNuke

Mine's all original, never been replaced, 122k miles.. No problems...It's an expensive part to get replaced, as it's not made anymore, but I wouldn't call it 'very unrealiable'...