I have an '02 Excursion with a 7.3 Truck has 327K miles. Since '06 I have been driving the truck with an 80 HP Econo tune from DP Tuner in the PCM.


I've been fighting two issues since fall - poor running at startup and chewing up alternators.

I'll start with the poor running. As it started to get cold last fall I found the X getting hard to start. Discovered it had thrown P0672, P0674, P0676 and P0678 codes. All of the glow plugs were replaced at 225K miles, the mileage at the time I found the codes was about 298K. I didn't touch it at the time - I just parked it in my garage and plugged it in and had no issues starting/driving.

In February, I performed an ohm check on the GPs (at the connector outside the valve cover) and observed the following readings:

cylinder 2 no reading / open
cylinder 4 33 ohms
cylinder 6 27 ohms
cylinder 8 33 ohms

I went ahead and replaced the GPCM and the 4 glow plugs on the drivers side.

I should also note that I hooked up my AE and performed all the available tests with no unusual results. I also still parked it in my garage, but stopped plugging it in.

Replacing the GPCM did not help. The truck continued to experience rough running at startup, but once warmed up, ran smoothly with no noticeable issues. This issue continues today.

I went out this evening and hooked my AE again and not only discovered numerous codes, this time it produced many (seemingly) abnormal results upon running the various tests.

I attached screenshots of the DTCs stored in the PCM plus the three test results with abnormal results. I'm not terribly concerned about the P0475 because I gutted the EBPV many years ago and believe that is the result. I also get a P1211 which is due to the tune (I think - I've had it since installing the tune in '06).

I am not a diesel expert by any stretch of the imagination and need help interpreting what is going on here.


As for the alternator issue - the truck has been eating alternators since fall. At first it was going through them every 2-3 months, but the last two have only lasted 2-3 weeks each. I checked my batteries last weekend with a cheap-o hydrometer and replaced one of them because of an abnormal reading, but my digital voltmeter is down to 11.9v while running this evening, so another alternator has perished.

It never really occurred to me that these two issues could be related, but given the overlap in their timing, now I wonder if they might be.

 

What do the pins inside the connectors for the uvch look like. Both the connector for the gasket itself and the pigtail going to it. You may have a burnt pin shorting out don't know if that's causing the alternator problems or not, I kind of doubt it sounds like two separate problems

 

In addition to great advice above, inspect the pins on the green and black GPCM connectors. And eyeball the wires there too for damage. Under the 42 pin harness where it drapes across the valve cover is also possible, I suppose.

Ignore the codes for the KOER switch test. The unwritten instruction is you must activate each switch in order and AE tracks which ones fail. Without you pushing each button in order they will fail and presto; codes.

Cylinder contribution usually fails #3 and #8, no worries.

Anything hacked into the wiring recently? Stereo, alarm, LED lights etc?

A cheap voltmeter plugged into the cigar lighter might show interesting things. Static voltage, how big a dip with GPs on/starter engaged, etc.

 

For a foundation, I would start with pulling the chip and clicking the UVCH link in my signature.