MAF wire length sensitivity? ... other ideas?
11-22-2009, 01:35 PM
#1
On The Tree
Thread Starter
MAF wire length sensitivity? ... other ideas? Well, my MAF got lose from the airbox and fell into the pulley turning on the check engine light ... no roughness in engine power, just the chk eng light. The MAF body got a bit of a grind by the ps pulley and one of the wires to the MAF at the connector got cut. The body of the MAF looked intact where there doesn't seem to be a possibility of air leak.
After disconnecting the battery, I repaired the cut wire (brown wire at the end of the connector opposite the yellow wire at the other end) by soldering in a 1" piece of wire. The chk eng light was gone and everything was running fine afterwards with this temp fix. No check engine light continued after a few days of driving.
I ordered a replacement OEM Delphi connector with 12" length wire and soldered it into the original cable assembly ... which added about 11" inches to the original wiring harness assembly. Being the thorough person I am and since things were disassembled, I cleaned the throttle body with CRC TB cleaner and the the MAF with CRC MAF cleaner ... and patted myself on the back with a job well done.
Well, guess what happened next. The check engine light is back on after a few miles of driving and the engine runs rough now. The roughness was new and did so intermittently during moderate acceleration in any gear. The Autozone guys flashed the ECU which reflected P0062 (heater control circuit error for O2 sensor 3 in bank ...) and P0102 (MAF sensor condition with a return signal error ... probable cause per the report include vac hose leak or blocked, throttle body intake leak, BARO/MAP defective, VAF MAF sensor dirty or defective).
Would spraying throttle body cleaner past the butterfly and into the intake cause this issue? I would think that any residue would get burned off after the engine ran a bit ... it did start up rough which is what I'd expect.
Is the MAF signal path sensitive to the length of the wires? I am not familiar with the signals sent to and from the MAF thinking that these were dc levels and not very exotic. Are any of the signals sinusoidal / square wave / digital where the additional 11" in wiring might induce a change in resistance or impedance that the computer doesn't like? I visually checked the 4 sensors in the MAF body and everything looks OK ... nothing broken or floating around.
Any ideas would be greatly appreciated.
After disconnecting the battery, I repaired the cut wire (brown wire at the end of the connector opposite the yellow wire at the other end) by soldering in a 1" piece of wire. The chk eng light was gone and everything was running fine afterwards with this temp fix. No check engine light continued after a few days of driving.
I ordered a replacement OEM Delphi connector with 12" length wire and soldered it into the original cable assembly ... which added about 11" inches to the original wiring harness assembly. Being the thorough person I am and since things were disassembled, I cleaned the throttle body with CRC TB cleaner and the the MAF with CRC MAF cleaner ... and patted myself on the back with a job well done.
Well, guess what happened next. The check engine light is back on after a few miles of driving and the engine runs rough now. The roughness was new and did so intermittently during moderate acceleration in any gear. The Autozone guys flashed the ECU which reflected P0062 (heater control circuit error for O2 sensor 3 in bank ...) and P0102 (MAF sensor condition with a return signal error ... probable cause per the report include vac hose leak or blocked, throttle body intake leak, BARO/MAP defective, VAF MAF sensor dirty or defective).
Would spraying throttle body cleaner past the butterfly and into the intake cause this issue? I would think that any residue would get burned off after the engine ran a bit ... it did start up rough which is what I'd expect.
Is the MAF signal path sensitive to the length of the wires? I am not familiar with the signals sent to and from the MAF thinking that these were dc levels and not very exotic. Are any of the signals sinusoidal / square wave / digital where the additional 11" in wiring might induce a change in resistance or impedance that the computer doesn't like? I visually checked the 4 sensors in the MAF body and everything looks OK ... nothing broken or floating around.
Any ideas would be greatly appreciated.
11-22-2009, 02:22 PM
#2
No. I recently added about that much wire (and a 6-pin Weatherpack connector) during my 102mm MAF conversion with no issues at all.
Try swapping the V's MAF with the MAF from your Yukon (they're the same) and see what happens.
If it fixes the problem, then its an issue with your harness replacement (cold solder joint, wire color/connector position transposed, bad pin/plug in the connector, etc.).
Sometimes the colors on aftermarket replacement connectors are terminated on different pins in the connector than they are in the OEM connector. I've had this happen twice before (two different connector vendors), so now I think that it's best to count pins and verify colors on both to be sure.
Try swapping the V's MAF with the MAF from your Yukon (they're the same) and see what happens.
If it fixes the problem, then its an issue with your harness replacement (cold solder joint, wire color/connector position transposed, bad pin/plug in the connector, etc.).
Sometimes the colors on aftermarket replacement connectors are terminated on different pins in the connector than they are in the OEM connector. I've had this happen twice before (two different connector vendors), so now I think that it's best to count pins and verify colors on both to be sure.
11-22-2009, 09:41 PM
#4
On The Tree
Thread Starter
Thanks gents for your feedback.
You had the same idea I did scatillac. I did install my V's MAF into my wife's Yukon and it seems to be working fine ... no roughness, no check engine light, etc.
I I did check the wiring and compared with the oem connector. The wire color and order match up between the connectors and my solder skills look good enough for NASA. I did notice a gap on one of the pins of the new connector that doesn't exist on the others. This might be an issue. I used the same cable assembly guy in the past for my Impala's crank case position sensor and never had an issue with his work. He uses oem delphi parts and better than oem wire (larger gauge).
If the wiring and connector do check out, I wonder of the CRC throttle body spray I shot into the intake is causing my problems especially since it is a cleaner and light lubricant.
Thanks again.
You had the same idea I did scatillac. I did install my V's MAF into my wife's Yukon and it seems to be working fine ... no roughness, no check engine light, etc.
I I did check the wiring and compared with the oem connector. The wire color and order match up between the connectors and my solder skills look good enough for NASA. I did notice a gap on one of the pins of the new connector that doesn't exist on the others. This might be an issue. I used the same cable assembly guy in the past for my Impala's crank case position sensor and never had an issue with his work. He uses oem delphi parts and better than oem wire (larger gauge).
If the wiring and connector do check out, I wonder of the CRC throttle body spray I shot into the intake is causing my problems especially since it is a cleaner and light lubricant.
Thanks again.
11-24-2009, 04:50 PM
#5
On The Tree
Thread Starter
It was the connector after all. I installed the original maf electrical connector via a very quick solder job and the car works fine now. The source for the connector was very apologetic and is sending me a free replacement.
