Odd injector misfire

[CSM]

there were always a couple 2000hhp pumps that would lope at idle on my old frac crew. I loved listening to the cat 6412s. VrrrraaaattttttTTTTT VrrrraaaattttttTTTT VrrrraaaattttttTTTTT!

[Mopar1973Man]

Made a trip south to get some stuff today.

 

Misfire is only on a fully heated engine (190-195*F of coolant). More pronounced after a long uphill climb with high EGT's 800-1000*F. All you need to do to cancel the miss is either put your foot heavy on the brake heavy or turn on the A/C and its gone. If left to idle for extended period say 10 minutes or longer it will go away. If you shut down the engine for all of 1-2 minutes and start again its gone too.

[TFaoro]

You posted a pic of your crossover tubes in my thread, but I don't see an updater here 

[Mopar1973Man]

Cross over tubes done today. Sounds different I didn't notice any misfire on the way home.

[TFaoro]

Good work!

Keep this updated please! I think I'll make the treck up to Cummins tomorrow... I hate having to buy grid heater gaskets and O rings at the same time :/

[Mopar1973Man]

I've got a intake manifold gasket set coming to the shop. Mostly likely get it when I get home.

[bondobuilder]

Moparman, What was your resolution to the misfire? My truck is doing the same thing: when the engine is cold it idles like a top; at operating temperature is misfires. I can conceal the misfire by loading the engine turning on the A/C, pushing the brake or full lock turning the wheel. 

 

Consensus is pointing toward VP44, injectors, APPS, or cam or crank sensor. Any insight would be appreciated!

[Mopar1973Man]

Pull the injectors and have them tested. If they are low you can have them re-popped and flow matched. 90% of the time injectors are the cause of weird misfires. I've had 3 set of injectors drop below 260 bar and they start doing weird things. idle misfire hot, stalling after long haul at stop or lights, typically no smoke with it. Even my stock injectors after 150k miles still ran fin but the lowest injector was 260 bar and all 6 where idling fine and drive fine but low in power and supper low in MPG. (Bad spray, too much large droplets).

 

Hence how I found that pencil injector MISSING a hole. Pull them all and had the spray pattern checked. Sure enough its missing a hole and injector had to be replaced. 

 

Case C580 pencil injectors. #2 was phyiscally missing a hole and only had 3 holes. Bad spray pattern from the Case factory back in 1984... Yes weird crap does happen and some just live with it. Again pull the injectors and have them tested. 

 

Another Story is @pepsi71ocean he bought a set of 100 HP injectors and after 28k miles the pop pressures dropped to 280 bar which is still a fail. Bottom end is 293 bar. After pop testing and resetting the injectors now his truck is running good and way less smoke he also increased to 320 bar (if I'm not mistaken).

[LiveOak]

On 2/26/2015 at 12:23 PM, Mopar1973Man said:

Damn... My misfire came back.

 

So I called Eric and he's suggested I called Rock Mountain Cummins directly and get the crossover tubes. I was shocked at the price of $166.40 a piece ($998.40 for six) for cross over tubes.

 

So I called Eric back I'll order them from him.

 

Wow!  Mike, that sounds REALLY high to me.  I just had all of my injector crossover tubes replaced when I had new Bosch 275 RV injectors installed when I had the head gasket replaced.  

 

Geno's Garage has them for $41.95 each

 

https://www.genosgarage.com/product/dodge-ram-cummins-crossover-tubes-with-orings-3936953/Fuel-Injector-Components-Gaskets#minicart_a

 

I am late to this party and have not read all of the posts to the end of this thread so disregard if you have already got them.  

On 2/26/2015 at 5:21 PM, Mopar1973Man said:

190k miles as it stands right now. I was hoping to clear 200k miles before it was replaced. I might just do it anyways. Cram the last 10k on her and then... But first try the cross over tubes first. I'm not going to complain much being that pump is 11 years old and 190k miles. Served me well. The OEM VP44 was replaced at 50k miles in 2004 under dealer warranty with a P0216 error code and heavy white smoke issues in the mornings.

 

This was about the same time AND the same code my VP-44 threw when I had mine replaced under warranty in the last month and last 2 weeks of the warranty.  Guess I was not the only one with this issue ehh???  

[bondobuilder]

I'll update this thread with info from my experience, in case someone has the same issue(s):

 

As I described a few posts up, my truck had a very intermittent misfire only when warm. I could "cancel" or "hide" the misfire by pushing the brake pedal, turning the steering wheel or turning on the A/C. 

 

I took Mike's advice, pulled the injectors to have them pop tested and flow matched. I dropped them off at a local injection specialist at 8AM, I got a call at 9:15 that they are all leaking. I bought a set of stock replacements and installed them, and did a valve adjustment. And just like that, my truck runs like a top!

 

Thanks again for the reply, Mike!

[Mopar1973Man]

On 9/6/2020 at 5:06 AM, bondobuilder said:

I took Mike's advice, pulled the injectors to have them pop tested and flow matched. I dropped them off at a local injection specialist at 8AM, I got a call at 9:15 that they are all leaking. I bought a set of stock replacements and installed them, and did a valve adjustment. And just like that, my truck runs like a top!

 

Thanks again for the reply, Mike!

 

Typically that what happens... Even Common Rail has limits anyone that tells me the injectors are still good after 100k miles is "ignorance is bliss" state of mind. Remember that nozzle is in the firestorm every cycle of the piston where its heated to the temps of the cylinders. Then the pintle opening and closing. Then the minute amount of dirt that might get through a filter and presto worn injectors. I don't care who makes the injectors that all start to wear past the 100k mark. Even my Bosch Stock injectors at 150k miles still ran great but like DAP told me they were not even close to pop pressure. My stock set at 150k was about 260 bar. Minimum by Dodge FSM standards is 293 bar. Typically popped at 310 bar. Even Common Rail injectors will degrade and lose some of it pop pressure too over time. Just means the injector fire early. The way to detect injector life... What is the engine load if it near zero or at zero percent engine load the ECM is trying to defuel deeper to attempt to reach 800 RPM. Typically the injectors will cause the idle to rise like my 150k stock injectors idle at 850 to 860 RPM at 0% engine load. I just found another owner with 0% engine load and his idle is hanging at 805 to 810 RPM. Injectors are shot. 

Edited September 11, 2020 by Mopar1973Man