Correct, and yes you can look inside the MAF sensor immediatley after you shut down and see it glow, best done with a helper. This event is only to clean the impurities from the wire.....another way is to ground Term E at the ALDL with the ign on, shut the ign off and quickly look into the MAF sensor, you have to do this quickly to see the wire glow. All this does is confirms that the burn off function is working.
frank

 

I thought that was the case from what I'd been reading on the Forum.

So I wonder what's up with FLYLOWGUY's setup; he says he has two on his 85.

Jake

 

I've seen my burn off module up by the ECM like the shop manual says, but I agree it does not say what the 1 relay is behind my battery - part No. 10032081, which is the same number as the engine fan relay. I have an early 4+3. Could this be the MAF power relay?

The fuel pump relay and OD relay are the same part no. too.......how convenient.

 

I guess I have a couple unnecessarily replaced relays whose true functions are unknown.
But it sure runs great.

EDIT:
I went back and searched and read most of the preceeding threads about this subject:
http://forums.corvetteforum.com/sear...archid=1044892
It's confusing but from what I gather, there are various locations and types of maf relays. And there seems to have been some midyear changes.
My book says the '85 has a relay that both powers the maf and controls the burnoff timing too. It's supposed to be behind the right hush panel.

 

The service manual indicates no relays for the 85 per the wiring schematic and other info. The burnoff module must contain a relay to send voltage to the maf to clean it up. According to an earlier post, other relays were added in 1986.

I keep getting a code 33 after shutdown and not restarting the engine for a couple of days.

I have performed all the tests in the GM service manual for the burnoff module (code 33) and it indicates a bad maf. In other words it appears the burnoff is functioing properly. Proper voltage at the Maf connector.

I also performed the code 34 (maf test) which is to disconnect the maf connector and start the engine and let it run for 1 minute. If the code set is 33 (not 34), , then the maf is bad.

So, I will replace the maf and see what happens. Will keep you forum members informed in hopes it saves you time and money should you have this problem in the future.

 

I got a rebuilt MAF at Autozone for $150. The first one they gave me was goofy. It threw codes and acted funny. They warranteed it, and the second one runs perfect.
It's best not to shoot any cleaners or anything through a MAF sensor. The fragile innards will get messed up.

 

some good reading here!!! i have an 85 that i rarely drive and now it wont start unless i squirt gas down the throttle body...it has a code 33 right now...it will crank all day but no start...it has good fuel pressure(checked with a gauge) and i just started messing with it again.....anybody have any ideas??????

 

I may be wrong about some of this because your car is an 85 and it has some different characteristics than my 86.

when you first turn the ignition key to "ON" do you hear the fuel pump run for 2/3 seconds? It's suppose to.

You should have a cold start injector, too, that primes the engine for quick starting. There's a sensor in the front of the intake manifold for this and I believe the pulse width is determined by the coolant temp the ECM detects as you crank the engine.

First try disconnecting the battery for 30 seconds to clear the stored code. Then see if the engine will fire without manual priming.

Then try disconnecting the MAF connector and see if it starts any easier.

The same checking procedures should be used:

Visually check the MAF wires to see if any are broken: they're really thin so look carefully.

Tap the base of the MAF with the engine idling to see if the engines stumbles.

Try borrowing a MAF from someone who's running the same one. Many 'F' body (Camaros, Trans Ams, etc.) cars use the same MAF.

Hope this helps.

Jake

 

no start at all!!!the fuel squirted in the tb will let it run for a few seconds only....and i can hear the pump at key on(also has pressure when the gauge is hooked up )i removed maff all the way and still no start up........i am going to hook up a noid light and check for pulse this weekend

 

Check the injector fuses.

Jake

 

Ok, I have one question about my SES light staying on, and throwing code 33. My car runs fine. Doesnt hunt for idle, has power, allthough lt lopes pretty low, around 800 RPM, its seems to run fine. But when I reset the battery via disconnect, it still throws 33. I talked to the previous owner and he says it started throwing 33 when he put Headman headers on it, and hollowed the cats out. Id like to get rid of my SES light at the very least.

Oh, I have an 86L .. If anyone has a good spare MAF they wouldnt mind parting with, PM me.

thanks


dan

 

Chances are the engine is dropping out of closed loop at idle due to the 02 sensor cooling off. This is a common problem when long tube headers are installed. Going with a heated 02 is the cure for this problem; it's what I had to resort to. They're about $45.00 at AutoZone.

However, this should not be causing a code 33. When I found out that my long tubes were causing the system to drop out of closed loop, it was only because I was monitoring the system with Diacom. No code was set and the idle quality only barely changed.

When a code 33 is set, the system resorts to programmed tables in the PROM.

On the 86, you have two relays one or both of which could be causing the problem. There is a burn-off relay and a power relay, Both are mounted side by side on the firewall behind the battery.

I'd first visually check the MAF wires by removing the MAF and taking a look inside to see if one is perhaps broken.

I'd then do the tap test with the handle of a screwdriver on the underside of the MAF as the engine is idling. If the engine stumbles the MAF's electronics are bad.

I'd then check the voltage on both relays.

If none of that finds the cause, I'd swap in a borrowed MAF. As I posted before, many mid 80 year 'F' body cars use the same MAF.

I got my replacement MAF off a wrecked car at my local wrecking emporium for $50.00 I was able to zero in on the MAF as a problem by borrowing a friend's MAF off his 85 when cured my problem, so I then knew my MAF was bad.

Hope this helps.

Jake

 

Had a problem with an intermitent Maf sensor and didnt want to spend the bucks to guess on the problem. Dealer wanted 450 dollars for maf, mid america wanted 350 for a new one, mid won. The measured output was not good mid range. These do fail, mine failed around 80000 miles.

 

Mine too was intermittent as stated in the original thread.

It is now Fixed! The Shop Service manual was correct, replace the MAF dummy, though it doesn't elaborate on intermittent conditions.

The old MAF sensor has been in the car for the 16 years I've owned it and I have put 240,000 miles on it. It is most likely the original factory MAF, new world MAF record, 290,000 miles. The od had 50,000 on it when I bought the car.

By the way, I removed the screens from the old MAF when the 383 stroker went in a couple of years ago. Have not removed the screens from the new AC Delco MAF. Can't feel any difference in power, low or high rpms.

My experience leads me to suggest to all who own these cars, invest in the shop manual if you are inclined to trouble shoot problems and try to fix yourself. The Haynes is ok, but the shop manual is much better when it comes to diagnostics.