Mass Air Flow/Vane Air Flow Sensor Circuit Above Maximum Voltage (O,M,R) Causing CEL

[Rob95DFW]

Hello,

I have a 1995 Mustang GT with the following mods:

E Cam
Longtubes
Mac Prochamber
SLP Dumps
CAI
C&L 76mm MAF (Calibrated for 19lb Injectors)
No Smog Pump
All EGR is in place and hooked up

Everything else is stock. However, I am getting a 56 - Mass Air Flow/Vane Air Flow Sensor Circuit Above Maximum Voltage (O,M,R) code and I don't know what I need to do to get it resolved.

I have cleaned the MAF, replaced IAC (AutoZone part), replaced all vacuum lines, replaced EGR gasket and cleaned it, replaced TB/Upper Intake Manifold gasket.

When I replaced the IAC, the car began to have a hang idle issue as well. When I shift gears, the idle increseases 300 - 400 RPM and then will fall down. When I come to a complete stop the car will idle about 1100 RPM and eventually fall down.

I don't know what else to do with this. If I run the car, the CEL will illuminate, but if I turn the car off and re-start it, the CEl is off for a few minutes and then comes back on.

Any help would be appreciated!

Robert
1995 Mustang GT 5.0

 

[ttocs]

I would try replacing the maf and see if it clears it up. Double check the wiring going to it so ensure there is no bare copper showing or loose wires.

 

[Addermk2]

Disconnect the main ECU harness and the maf harness plugs. Check continuity at each end of pins 9 and 50. While both ends are disconnected, turn the key on, and look for voltage on pins 9 and 50. Also check the voltage on the red wire in the MAF harness.

Assuming your car does not have a tune. The 56 code you are getting it set by the ECM triggering PID VMAMAX. Basically either pins 9 or 50 are seeing more than 4.9vdc at a given time.

 

[Rob95DFW]

If they are getting more than 4.9 how do you fix that?

 

[toyman]

How can a '95 get a 2 digit code (56)? They are all 3 digits. MAF codes for the '94-'95 are 157, 158 and 159.

 

[Addermk2]

http://www.troublecodes.net/ford/