Lars87

Since I am having some MAF problems (code 33), it would be nice if somebody would bother looking up their MAF sensor while the car is idling, and then see how it looks when the engine is turned off.

Mine is red hot all the time, and dosent change when the engine is turned off, which lead me to think that its the MAF sensor.

Their isent anybody near me with a corvette that could check out my self, thats why I hope somebody remember or could look at their MAF behavior..

Best regards

Lars

GKK

Check the MAF "Burn Off relay" mounted on the firewall.

When you first start the engine the Burn Off relay sends current to the MAF sensor and the wire inside turns red hot for a split second to burn off any contaminants. The relay could be stuck in the open position.

MARDAG

That doesn't sound right...

Lars87

Well i have tried to switch the to realys aorund, and it dident help...
Infact witht he car idling, I have tried to remove both relays and it dident change a thing...just the same idle and everthing.........

Am starting to pull my hair any time soon....

CMYC4GO

I think the burn off relay should only activate on startup, and only for a seond or less. If it's staying on, even with the car off, then you have to have an open circut someplace. You'd better get it fixed pronto. Those MAF's aint cheap to replace, and those wires in it are hair fine. It doesn't take much to break them, and if that thing is staying hot all the time, I would imagine the constant heat might melt them.

Lars87

Well...The wires arent red hot, with the car off, but when idling the wires are Red hot all the time, then when you give it some throttle they go out, perhaps because of the air thats sucked into the MAF.

I have tried to switch the relays around, and it was still Red hot under idle....'

I just want sombody to confrim that their MAF wires arent red hot under idle...

kopbet89c4

I got a MAF from Autozone for $170. Its a Microtech MAF. One that doesn't have a thin wire on it anywhere and my car has been running perfect ever since. Your MAF is a Bosch. I never liked the fact there was something German in my car. That Bosch MAF is also very delicate and just gave out so I replaced mine with a better one that claims more CFM than a substandard Bosch POS. Yeah, while you're at it, replace those relays and get a better MAF.

Lars87

is that MAF a direct replacemnet?

ElisTwoCents

It should be that is the one Im running in my car right now...

kopbet89c4

Does good, doesn't it?

PierEagle

The Burn-Off operates when the key is turned OFF.
"Due to contaminates in the atmosphere, a residue may build up on the MAF sensor sensing wire. To maintain an accurate reading from the sensor, a "burn-off" cycle will occur, when the ignition is turned OFF,
after the engine had been running a specified amount of time, and engine is warmed up. The burn-off function is enabled when the ECM grounds CKT 900, which energizes the MAF Sensor burn-off relay."

"A burn-off signal to the MAF sensor, while running may indicate faulty wiring or components. A burn-off signal to the MAF sensor, while running, may result in a Code 33. Be sure relay connections are clean and check CKT 994 for a potential short to voltage."

As above, I would check the connections on the Power Relay and the Burn-Off Relay. Make they are clean, secure and no bare wires. Disconnect neg post on battery for 30-45 seconds to clear ALDL codes. Reconnect battery and run car for a while to see if code resets. If it does, I would REPLACE both, the Power and Burn-Off relays. Don't what the cost is there. About $10 each in U.S.. Clear code again and run to see if code resets. If it does, check for short in CKT 994. I would do these things before I condemned the MAF itself.

Good Luck

OzzyC4

Bought a pair of them at NAPA last fall for $6.71 each.

blue 85

Gust had this same problem need to run the tree in the shop manual pg 6e3-51 sounds like the burn off relay it located behind the bread box or tou have a bad ecm good luck

kopbet89c4

On 86s and later, I think the relay is between the battery and firewall.

PierEagle

They are mounted together in the same bracket, on the firewall, behind the battery.

REDC4CORVETTE

BURN OFF RELAY'S
According to chevy they should be serviced on a regular bassis,they don't say what a regular bassis is.
I would also check the plug and see if the pin's are good.

Lars87

I have just measured the voltage on the wires at the MAF connection.
I measured with the car idling. and pin A( blk/white) as ground


E(ppl)=14.32V - Power
D(DK BLU)=5,10V - MAF Relay Burn of signal
C(DK GRN)=4.17V - MAF Signal


Correct my if i got the wire names wrong...

Does this tell me that my MAF is in "burn off mode" all the time?

kopbet89c4

First, before the SES light comes on, take a measurement. After the SES light comes on again, take another measurement. Post the results up here,

Lars87

I will give it a try..But I cant get the car to idle before the SES light come on.....
I´ll have to do one start for each wire.

Lars87

I have made some measurements on the MAF connection, before the SES some on, and on when the SES have come on.

Without SES light:

E(ppl)=14.3V - Power
D(DK BLU)=5,01V - MAF Relay Burn of signal
C(DK GRN)=4.76V - MAF Signal

With SES light on:

E(ppl)=14.3V - Power
D(DK BLU)=4.28V - MAF Relay Burn of signal
C(DK GRN)=3.76V - MAF Signal


Before I shut the engine off, I tried to disconnect the MAF completly, by disconnecting the connector under the MAF sensor. It made NO diffenrence at all, the car had the same idle.....