Blueangel73

I recently acquired a 97' Z28, was told that there could be a possible short in the harness in the engine bay. He said he believed it was somewhere in the harness near the connectors where the MAF sensor, Ignition coil and Coil module are located. I noticed that the MAF sensor connector looked to be damaged and confirmed that although the pink wire going to the MAF sensor looked to be intacted, it did look flimsy. If the wires inside the shielding aren't fully intact any more (been bent/twisted so much that the wire itself has broken apart but not the shielding), making intermittent contact in the shielding, could this completely prevent the engine (no contact) from starting or cause the engine to just die when running (had contact but lost it via vibrations or movement at wires the possible damaged location).

Injuneer

Typically, the harness bundle that contains the MAF sensor wiring also contains the coil and ICM connectors, four injector connectors for the driver side of the engine, and the coolant sensor connector for the dash gauge. A single injector problem wouldn't shut the engine down. Coolant temp gauge has no affect on anything other than the gauge. A short in the ICM or coil wire would cause the problems you describe. In theory, if the MAF sensor is lost the PCM defaults to speed-density, and the engine should still start and stay running. But that's not always the case.

A common problem, associated primarily with the 97, is the pink wire that supplies 12V to the MAF sensor breaks somewhere in the harness, and sets a code for an MAF fault. And therein lies a clue to how you solve your problem. Problems with any of those circuits except the coolant gauge should set trouble codes. Does the SES light come on? Have you scanned it for codes?

Blueangel73

Thanks for the feed back!

Only code is the MAF, previous owner (I have known for over 20yrs) says it is new, but the starting/stalling/running issue isn't. He showed me that just moving the bundle effects it, car wouldn't start, shook the bundle and it started up (sometime a few shakes needed), move the bundle and it stalls, I think its a short or a faulty wire. I ordered a new pigtail to fix the MAF connector, hopefully that removes the MAF code and allows me to further trouble shoot.

I pulled the harness shielding back and didn't notice any obvious damage to any of the wires, it all appears to be OEM (just old and faded). Maybe you can confirm something for me. The black w/ white stripe wire on the MAF goes back to a point where it looks like it is joined up with a few other black w/white strip wires and a all black wire, I am guessing these are all sensor ground wires and the all black wire goes to the ECM. There are two other all black wires in the harness, one goes into the ICM and the other is at a terminal point on the block at the ICM, which I believe is acting as a ground. The two tan w/ white stripe wires are also terminated at that point. All the pink wires seem to do the same thing as the blk /w wht wire and all go back to a centralized point and are tied together. Both tie together points for the blk w/ wht and the pink wires are both near the third injector on the drivers side. Does that all sound correct? Do you think its possible that there could be a short or faulty wire in either of those tie together points that could cause the issue?

Injuneer

Which code for the MAF? There are several. P0100 sets if the pink wire loses 12V. Pull the harness connector of the MAF sensor, and key on/engine off check the pink wire pin for 12V.... first between the pink wire pin and a chassis ground, then between the pink wire pin and the black/white ground wire pin. Jiggle the harness while testing.

The break in the pink wire is typically not at the connector, but somewhere back in the harness. Many people just replace the pink wire completely.

Blueangel73

If I remember correctly, P0100 looks correct, but I can't check now, not until I get the pig tail installed. Like I was saying the pink wire didn't look good at the connector, had been twisted way to much and broke the wires inside the shielding. The shielding separated at this point last nigh and confirmed the wires was broken. So when I get the pig tail installed I will be able to confirm what the code is and if it stays away when cleared. But even with the wire being broken I should be able to test the wire for 12v and see if there is an additional problem up the line.

The red arrow show where the wire was weakened from the twisting, this is where it broke. (sorry the pic is so big)


The red and pink arrows are the tie points I was referring to where the black w/white wires and the pink wires come together.

Blueangel73

I managed to fix my MAF sensor issue. The wires at the plugs had been so twisted up that they had broke all the wire withing the shielding on the pink wire. I could pull the wire and the shielding would stretch. So I ordered a pigtail connector to replace the plug and it worked, the code went away.

So, now that I fixed that issue, I have moved on to the running issue and harness sometimes cutting the motor out if the harness is moved. I isolated it down to either the connector at the MSD ignition or the ignition control module. When I move the wires at the connectors the engine would stall. So I ordered new pigtail for both connectors and will hopefully have them in and the issue fix by next weekend.