Air bubbles in Davco 382 - hard starting series 60

UPDATE

I may have this solved. Turns out some ####### changed out the starter and did not put the ground strap from the starter to the block back on. My ECM was getting heavily fluctuating voltage at startup. We'll see in the morning.

This also caused severe corrosion between my starter, starter bolts, and bellhousing. I hope it didn't screw my block or liners.

 

Don't think the issue is solved, I'll know better after this trip. It being so #### cold out really throws everything for a loop. We shall see. I have a Nexiq cable waiting for me down south.

 

My truck is a bit different than most, the ECM wiring does not go straight to the battery. Instead it goes to a fused 135 amp relay. It looks like the positive from the batteries to this relay is simply too small, it's half the size of the alternator wire. It looks like the alternator wire and another wire meet the positive at the relay on the non-fused side, and the power to the cab and ECM is on the fused side. First step is to put a larger positive from the batteries to the relay, it simply isn't large enough.

Next trip I will replace the ECM wiring, put a fuse in the battery box for it, and go directly to the batteries.

 

Still having issues, found a few more small electrical issues. One new thing I've noticed is when it's very cold it can develop a slight miss. So the problem can be narrowed down to a "cold miss". While making boost there won't be an issue. It was -28C and I was coasting for about half a mile, downshifted gave it throttle and there was a lag, then it took off like a rocket and there was smoke. Almost like the cylinders were puddling up or something? Cam timing is still a good idea.

I've done the following:

- Fixed 2 injector trim codes that were incorrect
- Checked cam - it is correct 8309
- Checked for air bubbles again
- Checked for bent valves, found something, will get a better idea tomorrow. It looks like one of the intake valves is maybe 2 thou lower than the rest, putting a square pipe across the valves you can just barely see sunlight under one of them. Will run a feeler gauge tomorrow.
- Obtained a Nexiq cable and all detroit software, ran cutout test with fan on, but this was before changing trim codes on #3 and #6:

Baseline 4.06 @ 600 rpm

#1 4.41
#2 4.00
#3 3.97
#4 4.12
#5 4.57
#6 3.93

Baseline 4.09 @ 1000 rpm:

#1 4.77
#2 4.70
#3 4.71
#4 4.85
#5 4.81
#6 4.77

Injector response times:

#1 1.13
#2 1.14
#3 1.13
#4 1.12
#5 1.13
#6 1.05

Ran a few graphs in DDDL while starting, 12v and sensor voltage seems stable, none of the sensors seem to spike or anything. One oddity is it does not show BOI (Beginning of Injection, timing advance) for some reason, does anyone know how to turn that on? Also instead of AIT (Air intake temp) it reads ambient temp, which seems odd.

Tomorrow I'm going to replace the injector harness, I've had a few people say that it can cause a cold misfire. Also going to check cam timing and further look at the valves.

After this I'm going to #### around with the starting timing. But that cold misfire is still baffling me, that makes me think cam. I doubt Detroit would get the cold starting wrong. It was tuned by Leon, but he only touched the timing above a certain RPM and it still started bad with factory tune and known good ECM. Also, while cranking the voltage at the battery drops to about 10.8. I have the big 44MT starter, so it will drain a bit more, but that seems excessive.

 

Cam? Yes I will do that tomorrow. Will follow service manual, and I should have everything I need

 

See that's awful interesting because the IAT doesn't actually show up in DDDL, but "ambient temperature" does somehow? I should try disconnecting it see what that does. Also can I advance the cam if it's still within spec?