Here's some additional info.

http://www.thedieselstop.com/faq/949...les/032136.pdf

 

Thanks DND58, that diagnostic procedure is very helpful. However, it appears to me by following this procedure that pretty much ANY problem that could occur with this system (everything from bad plugs to bad GPCM to shorted or open wires in the control circuit from the PCM) should result in codes. I'm getting no codes. I'm really thinking that my performance chip may be the cause of this. Here's a post from someone who had a similar problem with this chip:

TS performance chip disabling glow plugs? - Diesel Forum - TheDieselStop.com

It seems unlikely that such a common product could have been shipped with a programming flaw like this, but I suppose it's possible. They do custom program each chip depending on the options you select. I'll find out this weekend when I take it out.

Battery voltage only drops to about 12 V from 12.6 when the GPCM is supposed to be powering the plugs, so I really don't think that the plugs are getting power. Someone else on this thread said that his voltage drops to around 11 V when the plugs are heating.

 

Yes, they do. At this point, I think you are taking the prudent move by removing the chip and going from there. I feel bad for initially stating that the chip is probably not the issue, because it is looking more like it may be.

 

I'll try taking the chip out this weekend.

 

Oil temp sensor?

 

Just reporting my findings on this.

First, I recalled that five years ago when my starter died when I put the new one in it cranked a lot faster. Slow cranking doesn't generate much compression heat so it can take longer to fire up. I've got a lifetime warranty on the starter so I swapped it for a new one and it does crank A LOT faster now; maybe 3 times faster. There was some corrosion on the connection from the battery so that might have been part of the slow cranking problem too. However, this didn't fix the hard to start when cold problem.

Finally, I took the performance chip out and the next cold morning it fired right up. I've done this several times now; attempt to start on a cold morning with chip in, hard to start. Remove chip and it fires right up (and I mean INSTANTLY) the next cold morning, so it does appear that the chip is the culprit. Time to contact TS Performance. Maybe this chip was set up for an engine with a glow plug relay rather than a control module?

I went ahead and pulled the Autolite plugs and replaced with Motorcraft. All the Autolites came out easy, looked great, and all tested at 1 ohm so I think they were perfectly good, but better safe than sorry. I just put those plugs in a few years ago so maybe Autolite had changed the design by then.

 

Glad to hear you got them replaced. Also sorry to hear it was your chip, but glad at the same time. It should be an easy fix to re-program it. Contact TS, like you said, and see if there is a difference in programming between relay equipped trucks, and GPCM equipped. I would be very interested to hear the answer.

 

Pardon me for jumping in,,how hard is it to replace a glow plug?

 

It's not bad. Pop the valve covers off, pull the wire from each glowplug, and extract the glowplug. The trickiest part is getting the glowplug out. The rocker arm is right there, in the way of spinning the glowplug out with a socket. The trick is to take a deep 1/4" drive 10mm socket and just loosen the plug, then leave it there for the next step. Take a piece of tubing (I use 5/16" plastic fuel tubing) and slide it over the top of the glowplug. Once the tubing is firmly seated, you just spin the glowplug out.

 

Thanks Rich, nice trick btw

 

I got the chip back from TS Performance after the no-charge reflash. Problem solved. Lesson for all Excursion owners; make sure you tell your Tuner that you've got California emissions or your glow plugs may stop working.

 

Glad you got it fixed. Free even!

 

I have a 2002 F350, California truck, so I also have GP control module, not GP relay. Like bradleyj, my truck is starting harder than it used to, even though GPCM looks Ok, I put in 2 new batteries, new starter. Question: would all the GP fail codes generate a check engine light? I think so...

 

With a stock ECU program and a GPCM pretty much any glow plug system problems should generate a CEL. Have you checked for codes even if you don't have a CEL?

 

I have and didn't get any...but my "code scanner" is actually my programmer, which i've run for over 10 years without an issue...trying to stay on the outside of the VC, but maybe that's the next step...without a CEL light, though.....hmmm