Rough/Disgusting Diesel Startup

[nemesisnight]

Here is a pic of my old GPR from the doghouse from when I tore my engine all apart for new injectors, crossover, HPOP, IPR, etc, etc , you can see it sits directly behind the alternator (upper right) as Saline mentioned. I replaced mine even though it was fine while I had it apart with a monster one from here http://www.dieselorings.com/16-009-white-rodgers-stancor-586-902-monster-glow-plug-relay.html

[Bbasso]

I did the AIH delete just over 2 yrs ago and zero complaints.

[saline]

pod is correct, the front is the air intake heater relay not the starter relay as I originally stated.

And holy hell nemesisnight!!! That's the cleanest 7.3L valley I've ever seen!

[maxswasser]

Originally Posted by saline

pod is correct, the front is the air intake heater relay not the starter relay as I originally stated.

And holy hell nemesisnight!!! That's the cleanest 7.3L valley I've ever seen!

Hmmm. So maybe the GPR isn't blown and the AIH relay is bad instead. I did not see two relays in there, so who knows which one I checked? Should the AIH relay be getting power when the key is on? I will try and test it again tomorrow.

[Ben10281]

Just out of curiosity, what were your opacity numbers on the CO emissions test?

I have noticed an increase in my numbers from last year's test to this year's test and will likely need to start hunting around to figure out why.

[maxswasser]

So definitely don’t even have a gpr. Insead have a gpcm. Do these go bad? Also, when I had the key set to “on” there was no power to the aih relay. Should that be getting power for a cold startup?

[carringb]

The GPCM should trigger an OBD2 code if there's a fault, as required under CARB emissions. That said.... I'm not sure it would trigger a code for an open glow-plug circuit, which can happen from both a broken wire, or an old glow plug with excess resistance.

[pod]

Iirc, the AIH doesn't energize at startup, but only during extended idle at low temps.
I also believe the GPCM can have its own code (P0670 possibly), but there are also other codes in the glow plug circuitry that can be issued as carringb noted.
I have the same setup as you (with GPCM) and I'm chasing down p0671-p0678 after a cold start. I've prepped to replace GPCM (as well as UVCH and GP's) as I've heard they can go bad just like the GPR.