So for awhile now, cylinders 2 and 8 where always higher than the rest on the cct. It feels like a miss. I get no codes on my predator, and the dealer gets no codes, but I know something isn't as good as it could be. I took the truck to a local diesel performance shop that understands our trucks with tuners and aftermarket parts. The tech said it was most likely my injectors, but they only have 30k on them, so I have a hard time thinking that could be the issue. Im at a loss hear, especially since my last compression test showed all cylinders pretty equal, but low, at about 370psi each. Any ideas???

 

Sounds kind of like the mystery symptoms that started when the released the "improved" gray CPS to me.

 

Im running the black one

 

And I have a spare black and grey one, maybe it wouldn't hurt to swap them out. As im texting this, my rpms are going up and down a little like if the AC was kicking in. Damn gremlins.....

 

Where did you get the injectors? Anyway to get live data so you can tell us actual numbers instead of just contribution test codes? Is it 2 & 8 or 3 & 8? 3 & 8 are the ones commonly tied to the CPS.

Swap 2 & 4 and 6 & 8 and see which cylinders end up with the problem. The issue will either stay in the same holes or follow the injectors.

 

Hey Chris I got them from Swamps, and in the email I got back from Dave, he almost sounded offended thatr I could make the accusation that it's his injectors- and I wanna believe him, 'cause sticks just don't go bad in 30k- but I still need to figure out what the hell is going on.

So you want numbers, here's some numbers for you, all where taken on the DP 80E setting, as that's what I normally keep it in, and were read with my Predator tuner/scanner;

Cylinder contribution, low to high
1- 0.0- 0.7
2- 0.5- 0.8
3- 0
4- 0
5- 0
6- 0
7- 0.1- 0.7
8- 2.1- 2.6

MAPV- 1.38 - 1.45

Mass Fuel Desired- 3.2 - 3.8

ICP (mpa) 4.76- 4.87
ICP v- 1.6- 1.92

RPM's- 668- 705

So you can see, my issue seems to be with the first and last two cylinders at each end of te engine. I don't know if it's a fuel issue, but my fuel pressure is holding at 65, and I'm running a regulated return, both in at the front, exit the back, into the regulator and back to tank.

I just swapped in a spare black w/purple o-ring CPS I had, don't think it made a difference, so I think it's safe to rule that out.

I can swap the injectors around, but if the problem stays with the cylinders, then what? Could the damn engine wiring harness be bad? It looks old and worn out, but my knowledge of electrical circuits is they're either bad or good, no real in between, with the exception of an intermittant ground.

I'm looking to try damn near anything here, throw some ideas guys!!!

 

I expected to see worse Danny. Those numbers don't look bad at all. I'm guessing with those injectors and your mods, if you want a smoother idle you'll need to get live tuning to smooth it out more.

I'm also of the opinion that 0% on all 8 when fully warmed up is more of a theoretical, looks good on paper, than a real world goal to shoot for.

 

My thoughts exactly, Live tuning will do wonders for your truck.

 

I know it will but Jody won't be coming my way anytime soon. Thing

 

Is I live tuned it 3 yards ago, don't know what changed...

 

I would agree with these guys... they look good. Mine are better at 310K, but alot of guys with 1/3 the miles as I do have higher numbers than that. I agree on the live tuning. Never had it or even a DP-Tuner, but I know it won't ever be "right" until Jody can live tune it. Only thing I can't quite understand is why numbers 1 and 2... 8 is normal. Usually 3 and 8 are a tad higher. I don't know, I just find that the only thing "odd". As for the overall values, again I don't think they're bad at all.

 

My truck has similar issues, but it's #3 and #8... I chalked it up to the CPS, and haven't got around to swapping a new one in yet (I have the gray one) My idle is a little rough at OP Temp. Yesterday I dumped a bottle of BG 44k in the tank and made an interesting observation. After ~50 miles the idle smoothed out considerably and

I drive a very consistent, mostly flat 40 miles to work each day. Most of the way my cruse is set to 65mph, I have an AIC that digitally shows my rpm, so that equates to 1734-1738 rpms and they would fluctuate constantly. Yesterday on my way home I noticed the rpms were 1742 and only fluctuated 2 rpm, and not as often. I hit the coast once to see if I was just 1 mph faster, and I wasn't. Looks like with just 50 miles on the injector cleaner where I was getting 1734-1738 rpm for a given amount of fuel, I'm now getting 1742! You wouldn't be able to tell this with out a digital rpm gauge and I believe proof positive the cleaner is actually making a difference. I'll do some more testing, and hook my AE up this weekend. Might be something to look into.

 

What's bg44?

 

BG Website

 

Ummmmmm...aren't you supposed to use BG 244 for diesels? I thought the 44k was for gas engines.