I've had an issue with my truck not wanting to start. It doesn't happen all the time, but it's becoming a problem since I'm about to drive to Houston next week towing a trailer.

I get a code P1277 (Cylinder #7 Open circuit, open injector, failed IDM). This is the only code I get (does NOT set a P1316), and only pops up under a KOEO test or an Injector Buzz test. It does not pop up on it's own, does not set a check engine light, and doesn't come up under any other tests. With the engine fully warm, cylinder #7 shows 0% change in rotational velocity. All other cylinders are normal range.

The problems I have is my truck will randomly not start. Another issue is that sometimes it does start, but acts like it's only running on half the cylinders. When it does this, I'll kill the engine, and restart over and over again until it runs correctly (it will not clear up on it's own, I have to recrank the truck to fix the problem). When it acts like it runs on only half the cylinders, it does not trigger any codes, and it smokes like crazy (grey colored smoke). I've pulled valve covers off way more times than I'd like to count, and the UVC harnesses are fully clipped in (and have the updated clips to keep them from popping off).

So I'm seriously doubting it's a UVC harness issue (no P1316 that is typically associated with it). It does this with or without a chip. With very little to go on, I'm not sure what to start checking. I'm going to re-ohm the passenger's side valve cover one more time just to make sure, but after that I need some suggestions.

Anyone?

 

Might check the bottom of that huge wire bundle on the drivers side valve cover, might have a wire rubbing through on it. think that would be my next look after UVCH

 

Ohm'ed out the UVC harnesses. Glow plugs are 0.7, injectors at 3.5. So UVC is good.

 

Yeah I had it off not too long ago and never saw anything when I checked it out. Guess I'll take another peek and see if anything new has popped up.

 

With all that smoke you mention it sounds to me like #7 injector is giving up the ghost and taking out the right bank.

 

Might suspect a IDM issue. Had a pretty wet winter up there, and a little water goes a long way...

 

What's strange is that it only smokes when it starts up rough. If it starts up normally, there's no smoke, and it runs fine. It also has no issues while it's running (ie. it won't start running rough on it's own after the engine is running normally, it only happens immediately after cranking).

Also the rough starts happen whether the engine is warm or cold. I haven't been able to pinpoint what triggers it. It's all random.

 

Yeah that's kind of where I'm stuck at too. I checked the wiring harness going into both valve covers, and checked for anything that has rubbed bare. All the wires look good, and there's no chaffing anywhere.

I'm not really sure if water got in there or not. We didn't get much snow this winter compared to previous years, and I only put about 3000 miles on my truck since November. It's been parked in the driveway most of the time.

Anyone in the Denver area have a spare IDM that I can swap in and test?

 

Well I have an idea to try before swapping an IDM out. I think I'm going to pull the valve cover off on the passenger's side, then swap the connectors on #5 and #7 (don't worry, I won't start the truck like this). With them swapped, I'll do another buzz test and see if the problem moves to #5, or stays with #7.

Thoughts?

 

good idea!

 

Good idea Curtis if there is some type of intermittant failure of some sort on an injector coil it may cause the IDM to shut down the bank.

 

Hmmm.... interesting. I've never heard of that before.

 

hi jim and guys,
hows everyone?

 

You could swap the solenoids if you wanted.

If it were me I'd focus on the no start condition. I've seen a bad injector soleniod take out the entire bank. Truck started up every time with no issues (other than missing on half the cylinders).

When you get the no start, any hints from the idiot lights not acting normal? Any smoke out the tailpipe while cranking? Check the wiring below and behind the 42 pin connector, the wiring harness over the driver front shock, the IPR & ICP wiring for any chaffing, etc.

Have you done the 140 mod to your IDM? If so, I'd pull it and inspect the solder connection to be on the safe side. I'd think IDM issues too, but that should have tripped some sort of code during the no start? Are you cranking a good 25 seconds or so during the no start condition to try and trip any codes?

 

Ok, so it could be a solenoid issue with my truck rather than an IDM issue. By swapping the connectors tomorrow and running a buzz test, if the problem remains with the #7 injector (would show up as #5 with the wires swapped), then that would tell me it's most likely a bad solenoid. If it follows the wire instead, then it's probably an IDM issue, unless I somehow missed a chaffed wire somewhere.

All gauges and dash light have been normal every time this has happened.

Yes, lots of smoke. ICP continues to rise as I crank also. So with the ICP going up and the smoke, it's trying to fire.

Yeah I checked all that, didn't see any signs of chaffing anywhere. I'll check again depending on the results of my testing tomorrow.

Still the same original unmodified IDM.

I was thinking so too, but wondered why it didn't until you and megawatt mentioned that a bad solenoid can disable the entire bank. So now I'm leaning more towards testing the solenoid first.

Yeah one time when it really wouldn't start at all I did some extended cranking, and didn't get any codes. It's odd that it won't trip any codes at all (other than my normal AIH delete and EBPV delete), and only pulls the P1277 with a buzz test or KOEO test. No other times will it display a P1277. No 1316 for the IDM, or anything else related.