RE: MAF Sensor 1986 Corvette HELP!!
Thread Starter
Pro
Joined: Nov 2006
Posts: 727
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From: Ocean City Maryland
RE: MAF Sensor 1986 Corvette HELP!!
How can I tell if the MAF sensor is bad? I replaced the fuel puimp which I know had a drain down issue so that problem is resolved, the rail is holding pressure now but the caqr won't start until I unplug the MAF but it still won't idle in that configuration. Help!!
Le Mans Master
Joined: Jan 2003
Posts: 5,858
Likes: 7
From: Santa Maria CA
If you can't track one down, and if you want to be really sneaky, just buy a new one from the parts stores. Swap it into your car and see if the problem goes away. If it does not, just put the MAF back in the box and make sure it's clean and immaculate the way you got it. Then just return it. If it works, keep it. 
I've fixed/diagnosed several problems like this because I had no other choice.
I've fixed/diagnosed several problems like this because I had no other choice.
Safety Car
Joined: Jul 2004
Posts: 3,840
Likes: 30
...after checking any relays (oops, i forgot, no codes displayed), UNPLUG the maf and if the car "runs" better, there might be your answer...there are a few posts on this if i recall correctly...
Le Mans Master
Joined: Jan 2003
Posts: 5,858
Likes: 7
From: Santa Maria CA
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Safety Car
Joined: Jul 2004
Posts: 3,840
Likes: 30
Le Mans Master
Joined: Jan 2003
Posts: 5,858
Likes: 7
From: Santa Maria CA
He had already done that before you posted. Says his car only starts with it unplugged.
Safety Car
Joined: Jul 2004
Posts: 3,840
Likes: 30
...do a search on the subject...
Thread Starter
Pro
Joined: Nov 2006
Posts: 727
Likes: 0
From: Ocean City Maryland
Re: Maf
Well Carlise show is coming so I have to hurry and get this car back on the road, I go every year and am looking forward to driving it there. I'm only 1 1/2 hours from it. Darn it!!!
Le Mans Master
Joined: Jul 2007
Posts: 5,043
Likes: 8
From: Tampa Florida
MAF Test
MAF test:
Below is the Fuel pump circuit/MAF circuit. The two circuits connect to a degree. A possible culprit for your car's condition could be low voltage on on circuit 998 - which restricts the injectors pulse per second. Good news it's easy to test it! All you need is a noid light, a dc volt meter and a long piece of wire. Noid light should be hooked up in series with RED lead of the voltage meter.
Test: (Test assumes that car battery is fully charged at 12v! Lower battery voltages may produce lower test results)
Hook one end of a long piece of wire from the a postive 12v source (battery) and now connect the other end of this jumper wire to term"G" on the ALCL.
With the Noid light hooked up in series with RED lead of the voltage meter now ground the meter's other lead (black)to the engine or negative battery post). With the MAF sensor hooked up push into the MAF's middle wire - the voltage on this wire(the middle wire - dark green)should be 2.5v with the key in the "on" position and a postive 12v jumper wire to term"G" on the ALCL. If less than 2v it's most likely a bad MAF sensor!
Push into the same wire with a test probe.With the MAF un-hooked the voltage should read 5 v with the key in the "on" position and a postive jumper wire to term"G" on the ALCL. If less than 5v wire may be grounded/shorted out or you could have a bad ECM.
With the MAF still unplugged you can also test ensure that you have 12volts going to pin "E" (circuit 993).
Below is the Fuel pump circuit/MAF circuit. The two circuits connect to a degree. A possible culprit for your car's condition could be low voltage on on circuit 998 - which restricts the injectors pulse per second. Good news it's easy to test it! All you need is a noid light, a dc volt meter and a long piece of wire. Noid light should be hooked up in series with RED lead of the voltage meter.
Test: (Test assumes that car battery is fully charged at 12v! Lower battery voltages may produce lower test results)
Hook one end of a long piece of wire from the a postive 12v source (battery) and now connect the other end of this jumper wire to term"G" on the ALCL.
With the Noid light hooked up in series with RED lead of the voltage meter now ground the meter's other lead (black)to the engine or negative battery post). With the MAF sensor hooked up push into the MAF's middle wire - the voltage on this wire(the middle wire - dark green)should be 2.5v with the key in the "on" position and a postive 12v jumper wire to term"G" on the ALCL. If less than 2v it's most likely a bad MAF sensor!
Push into the same wire with a test probe.With the MAF un-hooked the voltage should read 5 v with the key in the "on" position and a postive jumper wire to term"G" on the ALCL. If less than 5v wire may be grounded/shorted out or you could have a bad ECM.
With the MAF still unplugged you can also test ensure that you have 12volts going to pin "E" (circuit 993).
Race Director
Joined: Sep 2003
Posts: 16,837
Likes: 337
From: Database Error Indiana
Replace the relays. I have had MAF codes 2 times 6 years apart. Replaced both relays both times. Never the MAF sensor itself. About 129 k miles on the car now. Relays suck, but at least they are cheap. 
