Fast Ticking at Full Load, Injector Seal?

[dmaxdallas]

Hey guys,

So I've recently had my truck out after having the top end of the motor apart and adding some 65 overs and a Stg2r. After chasing other issues I've finally been able to start getting some miles on the truck. Last night while driving and actually laying into it for the first time I noticed something odd, a ticking/clicking noise coming from what seems to be the driver's side of the motor when I was at full throttle/full load. The ticking was quite fast paced and basically only present when at full throttle. I was thinking exhaust leak at first but the fact that I am struggling to hear any out of place noises while at low speeds/low load and idle is making me think otherwise. Basically I'm starting to lean towards one or more of the injectors leaking compression past the copper seal. When I put everything back together I spent an excessive amount of time cleaning and checking the injector bores so I was pretty certain I wouldn't have this issue; however, some of the signs are still pointing in that direction.

What I'm looking for is any advice on how to pinpoint which specific injectors the issue might be coming from instead of just pulling them all again. I was thinking that running a compression tester on each of the cylinders might reveal more and I have access to one if that would indeed help.

Attached is the balance rates taken in park with coolant temp around 175 degrees. The injectors were brand new with Bosch Motorsport nozzles. I have the flow data if anyone is interested.

I was thinking that the higher ones could potentially be culprits but then again this is simply a guess as I haven't dealt with this issue before, and along with this do the injector numbers on the CTS correspond with the traditional dmax cylinder numbering?

Lastly, are they any other possibilities from all of your collective experience that this issue could potentially be, as I don't want to jump to conclusions based upon my somewhat limited knowledge/experience in this realm.



I am hesitant to drive the truck much more until I figure out if the injector seals are in fact the issue because I don’t want the injector(s) to become coked and stuck in the bores causing difficult removal.

Any and all input is greatly appreciated

Thanks
Dallas

 

[fastpunker]

Your thought of doing a compression test first is a good idea... great starting point, pay attention to cylinders 6&8.. the positive numbers are a bit concerning. A positive number can mean a bent rod... don't want to scare you, but its the truth. Good luck

 

[BLACKMAX1]

Are any of your injectors wet with fuel? You can unplug your cp3 regulator then start you truck and let it idle at full rail while checking each one, this way you wouldn't have to pull any and would see/hear any leaks. I wouldn't be worried about those balance rates.

 

[dmaxdallas]

Your thought of doing a compression test first is a good idea... great starting point, pay attention to cylinders 6&8.. the positive numbers are a bit concerning. A positive number can mean a bent rod... don't want to scare you, but its the truth. Good luck

Lets hope its not rods yet! was hoping she'd live a bit longer ha

Can hopefully get a compression tester on it this weekend.

 

[dmaxdallas]

Are any of your injectors wet with fuel? You can unplug your cp3 regulator then start you truck and let it idle at full rail while checking each one, this way you wouldn't have to pull any and would see/hear any leaks. I wouldn't be worried about those balance rates.

All injectors are dry. I'm more concerned that the copper crush washer may be leaking compression by, but I'm thinking it would be hard to tell at idle as the rubber o-ring on the injector body would block most of the carbon from spreading to the exposed portion of the injector I would think.

 

[IOWA LLY]

What did you torque the injector hold down bolts to?

Did you clean the bolt holes out before you installed the hold down bolts?

Did you install the bolts dry, or with lube?

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[dmaxdallas]

What did you torque the injector hold down bolts to?

Did you clean the bolt holes out before you installed the hold down bolts?

Did you install the bolts dry, or with lube?

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22 ft/lbs IIRC

I attempted to clean the bolt holes best I could and I installed them dry, thinking I should probably double check proper torque on them to begin with

Also not sure how relevant this piece of info is but this is on all an optimized stock tune for now

 

[IOWA LLY]

I'd start pulling injectors on the driver side. You should be able to tell which one is leaking.

I spray some brake parts cleaner down the bolt hole, then use compressed air to blow the crap back out. Repeat until clean. Stuff a rag down the injector bore to keep stuff from falling in there.

I had an issue with my LLY leaking around the copper washers after I first built the engine. Ever since I've always taken extra care to ensure proper torque and I haven't ever had an issue since.

I use arp assembly lube on the bolts. Under the head, and the threads. I've always torqued them to 24 ft lbs. Then once there all torqued I back them off and re-torque. I'm sure this isn't all necessary, and probably somewhat overkill but once I find something that works I stick with it....

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[BLACKMAX1]

Did you reuse the bolts? I've stretched two of mine, one blew the oring and was pushing fuel out and the other was pushing air out. I agree with what Iowa said as well, I also torque down the injector, install the fuel line then go back and check the torque.

 

[dmaxdallas]

Did you reuse the bolts? I've stretched two of mine, one blew the oring and was pushing fuel out and the other was pushing air out. I agree with what Iowa said as well, I also torque down the injector, install the fuel line then go back and check the torque.

These were fresh bolts, sounds like I'll just start digging into her

 

[Awenta]

I think a leak down test would be more useful here than a compression test.

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[x MadMAX DIESEL]

I usually just pull them bad boys out one by one to find it..... BUT an air plane trick would be wrap aluminum foil around the injector and drive the hell out of it. Leaking air will cut through it. Only thing is, idk how well you could cover the injector bores


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[TheBac]

Your thought of doing a compression test first is a good idea... great starting point, pay attention to cylinders 6&8.. the positive numbers are a bit concerning. A positive number can mean a bent rod... don't want to scare you, but its the truth. Good luck

What?!? If it was +15, then yeah...I could see your point, but +2?

Iowa has some very good ideas.

 

[BLACKMAX1]

Well just getting back to the basics, could the ticking your hearing be normal? You're not feeding normal injectors anymore. Are your fender liners in or out? You could also have someone hold your throttle down while you listen to each side and hear if there's air pushing out.

 

[dmaxdallas]

Well just getting back to the basics, could the ticking your hearing be normal? You're not feeding normal injectors anymore. Are your fender liners in or out? You could also have someone hold your throttle down while you listen to each side and hear if there's air pushing out.

Fender liners are in but all firewall and hood insulation has been removed

 

[x MadMAX DIESEL]

Some of those leaks take a lot more than compression test pressure to unseat. If you can tin foil (never tried on this) that's the best bet for finding air leaks


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[BLACKMAX1]

Fender liners are in but all firewall and hood insulation has been removed

Not going to say that's it, but what do you think.

 

[dmaxdallas]

Not going to say that's it, but what do you think.

I can definitely tell there's more engine noise than before but this ticking seems out of place and stands out a bit

 

[fastpunker]

What?!? If it was +15, then yeah...I could see your point, but +2?

Iowa has some very good ideas.

Yes, it is true.... if there is lower compression in that one cylinder than the others it causes an in balance in the back pressure being supplied to the injector nozzles.... i.e. less pressure the injector has to fight to spray the fuel into the cylinder. Less back pressure means it is easier for that injector to spray a bit more mm3 into that cylinder. Typically a balance rate will be over 12, or whatever, if there is a hole in a piston.
The balance rates are calculated via the rail pressure sensor using the calculation P1*V1=P2*V2, (P= pressure, V=volume) in other words the pressure in the rail just before and just after the injector is fired.... and this is also why our balance rates only show at idle (or barely above), because the software computational rates in our ECM's are not fast enough to do it at higher RPMs. and this leads to why one bad injector can throw off other balance rates. Because if one drains rail more than desired, the cp3 is unable to increase pressure back to desired in the uS between one injector firing and the next. Slight different pressures, even if only minimal psi differences, it will affect the outward volume spray.

 

[TheBac]

Yes, it is true.... if there is lower compression in that one cylinder than the others it causes an in balance in the back pressure being supplied to the injector nozzles.... i.e. less pressure the injector has to fight to spray the fuel into the cylinder. Less back pressure means it is easier for that injector to spray a bit more mm3 into that cylinder. Typically a balance rate will be over 12, or whatever, if there is a hole in a piston.
The balance rates are calculated via the rail pressure sensor using the calculation P1*V1=P2*V2, (P= pressure, V=volume) in other words the pressure in the rail just before and just after the injector is fired.... and this is also why our balance rates only show at idle (or barely above), because the software computational rates in our ECM's are not fast enough to do it at higher RPMs. and this leads to why one bad injector can throw off other balance rates. Because if one drains rail more than desired, the cp3 is unable to increase pressure back to desired in the uS between one injector firing and the next. Slight different pressures, even if only minimal psi differences, it will affect the outward volume spray.

But instead of jumping directly to bent rods, which IMO is the extreme, wouldnt you tend to think a slight + number would be more related to the natural variations in an engine? Slightly different ring seal, slightly different protrusion number, slightly different compression between cylinders. Even the differences inherent between individual injectors could cause the same thing.