Diagnosis Help

TARM · Jul 30, 2014

Have you confirmed fuel pressure is fine?

The way its happening stumbling then taking off fine and being better once warmed up does not sound like the typical HPOP going bad. Such as with the Stealths its usually the exact opposite i.e. once warm it falls on its face and dies but tends to be good when cold and the oil is thicker.

The high IPRs makes it sure seem like something oil related. You never see those kind of ramping up % at idle unless something is wrong. You could always try swapping out HPOPS to see as that is the next easiest step before tearing under the VC.

To me the one thing that stands out is what was related to when this all started. i.e. you installed the injectors. Before that everything was GTG right? Seems like that is where I would be looking. Be it oring or actual oil side injectors issues or somehow electrical I think them happening at the same time should be the focus.

strokin'_tatsch · Jul 30, 2014

Is the truck losing any oil? Any oil in the fuel system??? Is the fluctuation in ICP when it is idling rough greater than normal? If this started when the injectors were installed and has gotten worse, I'd start by checking that and ohm the electronics. If the wiring ohms OK, I'd yank the injectors and have them checked out by the vendor if you can afford the downtime. I've seen injector o-rings cause a very rough running condition when cold and then smooth out a bit once warm, but the truck was still low on power. That's where I'm leaning towards so far. A cut external o-ring or possibly some messed up internal o-rings. Even though internal o-rings don't fail very often, it is possible for them to be damaged during assembly..

V-Ref · Jul 30, 2014

backwoodsboy said:
Yeah I've got a few spares floating around the shop. I'll try swapping it out and see if any difference is made.

Tried to get a video tonight, but it was dark enough the auto focus on my camera wouldn't work. I'll try and get another tomorrow.
Summary:
60% TPS
850 RPM
2400 PSI ICP
30% IPR DC
This was trying to climb a short little hill onto a main road. Truck just sat there and lugged, then all of a sudden took off. Very strange.

Took it into town to get fuel, and on the return trip noticed it hazing while sitting at a stop light. Hazed through 1st and 2nd. Not sure if it cleared up in 3rd or if I was moving fast enough that it wasn't noticeable.
Then developed a miss in 3rd OD locked. First time it has had a miss once engine was up to temp.
Truck is going to get parked until I can investigate further.

Really sucks because I spent my days off prior to starting this new job doing the injector install, re-plumbing the fuel system and a bunch of other routine maintenance so I wouldn't have to touch the truck for a while. Result is I've gone from having a reliable rig to this chit.

TPS/IPR/DC/PW/ENG Rpm video would still be great....especially if you can catch in the act during its sluggish antics.

And don't sweat the reliability part...it's gonna be a good truck once you get this sorted out. I had a 200% nozzle 76mm inducer single truck that was super reliable....yours will be too.

Can you describe the replumbing of the fuel system you did. Can you walk us through what exactly your fuel system is now? Did you remove/reinstall the hpop during this maintenance/upgrade event?

backwoodsboy · Aug 8, 2014

Well since the cat is out of the bag over in General, I'll admit that these injector are MFI (maybe?), and were purchased through Greg.
They will be coming out of the truck this weekend, and if the symptoms clear up with my old set I will be contacting MFI to see what they can do to make things right.
First step is going to be confirming whether or not these are in-fact MFI injectors. I'm hoping they can provide me with the serial numbers on the solenoids (to prove that they actually built them) as well as a flow sheet of some sort.

Moral of the story, sometimes a good deal IS too good to be true.

backwoodsboy · Sep 1, 2014

Injectors are out.
6 of 8 have some degree of o-ring failure on the HPO side.
6 of 8 have less than 0.002" armature clearance.

Think I found the problem.

TARM · Sep 1, 2014

Well that I think answers your question right there. I would have them gone thru completely to make sure nothing else is out of spec.

lincolnlocker · Sep 1, 2014

backwoodsboy said:
Injectors are out.
6 of 8 have some degree of o-ring failure on the HPO side.
6 of 8 have less than 0.002" armature clearance.

Think I found the problem.

dam... well at least now you know whats up.

live life full throttle