ace4aday

OK. Here's my story.....About a mile after filling up a nearly empty gas tank, my Pathfinder quiet died at a red light. It started easily, but surged and slowed and quickly died, the CEL staying on. Luckily, we were only a half mile from home, a relatively straight shot with only two lights and we decided to risk it. We pulled into the driveway many stalls, starts, and a few horns and fingers later, and I proceeded straight to the toolbox.

The scanner reported 3 codes, P0100 - Mass Airflow sensor or circuit fault; P0325 - Knock sensor or circuit fault; and a P0100 Pending (I have no idea what Pending means). I start it up and it runs for a couple of seconds and dies. I pop the hood and start it up and it runs with the rpm constantly changing. There is also a tick tick ticking sound in time with the engine, similar in sound to a small electric discharge, coming from the area of the EGR valve. I shut everything off and clear the codes. I turn the vehicle on a it sounds great, strong, no ticking, nothing. I let it run for awhile and then hop in for a run up the street. I got to my turn around point and it dies. I limp it back home again. The P0100 error is back and so is the ticking.

While checking out the MAF, I notice I can kill the engine just by grabbing the wires behind the plug and wiggling very lightly. Repeatedly, without fail. Now I wondering...bad gas? Bad MAF? Bad wiring harness? I clear the code, and it doesn't always come back after I exercise my new-found godlike powers over the wiring harness. Next, I disconnect the harness and check the power and ground circuits to the sensor and got a nice even 12v. I reconnect the harness and back probe the signal wire. I get about 1.3v at idle and it runs up to about 1.8v at 2k rpm. Finally, I crawl under the dash and disconnect the wiring harness from the ECM. I checked continuity of the white and black signal wires between the MAF connector and the ECM harness while aggressively twisting and bending the MAF end of the harness. The annoying whine of my DMM confirms the wiring harness to be in good shape.

I plug everything back in, clear the codes, and start her up. She sounds nice until I touch the MAF wires which kills it instantly. The tick (and the P0100) is back when I start it up.

So what's the general consensus? Do MAF's die suddenly? Can an MAF failure manifest itself to look like a harness problem? Are they that sensitive? Could it be gas? Should I have the MAF itself further tested. Should I try cleaning it? Break down and change the MAF? Help!

smj999smj

The fact that it runs nice until you touch the MAF wires would lead me to believe you either have a wire that is broken within the insulation making intermittant contact, a loose pin terminal in the harness connector or a bad MAF. If the circuit proved good during the continuity test while wiggling the wires, the next thing I would do is tighten the terminals in the MAF harness connector to provide greater tension on the pins. If it still acts up, a new MAF sensor may be in order.

Running low on gas shouldn't affect the MAF sensor. At worst, it might damage the fuel pump and cause the engine to run lean, but I doubt that's the issue. You could always confirm a good fuel pump by testing the fuel pressure.

ace4aday

Thanks for the response...I tightened up the terminals in the connector and that didn't change anything. I can still kill it by touching the wires and sometimes by just placing a finger on the MAF housing.

As for the gas, I never went empty. I still had a couple of gallons. I just couldn't rule bad gas out since my Pathfinder died only a mile or so from the gas station. Just enough time to use up the old gas in the lines. Timing is everything.

Anybody ever use one of those remanufactured MAF's? A new one is soooo expensive.

ace4aday

I guess I'll find out. Broke down and bought one from Schuck's ($134 + $55 core). Put it in and everything runs great now. We'll see if it lasts!