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6.7 missing/ popping... i need some help

23385 Views 49 Replies 7 Participants Last post by  Alphamax81
looked everywhere on here for other threads with my symptoms with no luck. so here it is... just switched from h and s to efi live from fleece about 3 weeks ago. ran great till a few days ago. was driving to work at a steady speed and it had a little hiccup miss. Didn't think much of it. prior to this (night before) i got a map sensor code two times in a row after deleting them. when i went to leave work i had to give it a little bit of heavy throttle to keep up started missing/ popping. any time i would put a load on the motor as in heavy throttle or go up a hill it would have what i call a little hiccup miss or cut out got a split sec and you can feel the truck jerk back. when i made it home it had the a slight miss at idle but it would happen a random and just barely feel the truck jerk slightly. so i drove back to work and switched out both the sensors on the air intake and that seemed to help it.didnt notice a miss at idle and it feels like i have to really try to get it to miss under a load maybe once you get the revved up to 2800-3000 and get the boost around 40 it will really miss and jerk its worse. rail psi stays between 23-25kpsi. i think its electrical but what do i know. lol doubtful its an injector cause they just got tested a year ago and 5 rebuild by area diesel. has no smoke white at all on start up. any help is much appreciated!!
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If the tubes were leaking would it leak fuel in the oil?
No it returns in the same trac as the injectors do. Exits the rear of the head back to fuel tank.

The cooper washer is the seal on bottom and O-ring on top.
There is an allowable amount of fuel that will be returned. Even brand new injectors have return.

Allowable is 1.5 FL-OZ for 30sec crank time. (Dont Start)

Max 6 FL-OZ for 1min Idle time.
It starts quick and no white some what so ever. If the sensor on the rail or cp3 was bad surly it would throw a code right? I really think I'm leaning into getting the injectors or cp3 tested. Don't know which one to get tested first. Its 150-175 to get injectors cleaned and tested from area diesel. Don't have a clue who test cp3s or how much that cost

This morning going to work it did it even when it was lugging. But when it does it when it lugs its more like a slight miss not a pop. The more rpms is when the poping starts to happen
How long has the rail plug been installed?
You said this started after the sump instal.

Did you do anything else to the truck at this time? Instal CTS, Tap Any Wires, Rail Plug, ETC...
Rail plug has been in for atleast a year. I just did the sump that night. a week before i for it tuned we did valve springs, push rods and my nozzles but it just wouldnt hold rail at all. Week later i witched from mini max to fleece efi live and all was great for 2.5 weeks till this. On the morning this all started i had a buddy with me that wanted for feel the power so i slowed down a put and let it rev out in 4th-6th without any issue. 15 mins later just normal throttle it popped once and down hill from there. It was fine one min then 15 mins later is when i noticed it. Still no codes since i cleaned the map sensor.
Beings you've reused the connector tubes 5 times and only rebuilt 5 injectors, I think you need to check for high returns.

This will let you know if its injector/connector tube related.

If returns are normal, then its a good chance the cp3 is your problem.

Connector tubes will develope rings around the tips from sealing to the injectors. Over time and multiple uses the tend not seal properly.

The procedure is to cap the rail for each cylinder until the problem is isolated.

Fleece can test your cp3...
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cap the rail by taking the line off and putting a cap on it? I have never heard of this but ill do whatever it takes to get this unit back up on her feet. what if i did an injector kill test on one injector at a time and drove the truck to see if it quits popping on one of them. would that be the same a capping the rail? also can i visual inspect the tubs and see problems?
Part #4918298
Fuel System Leak Tester
Used to cut off injector fuel supply when diagnosing injector leakage
or malfunction. (Used on fuel rails with 18 mm threads).
cap the rail by taking the line off and putting a cap on it? I have never heard of this but ill do whatever it takes to get this unit back up on her feet. what if i did an injector kill test on one injector at a time and drove the truck to see if it quits popping on one of them. would that be the same a capping the rail? also can i visual inspect the tubs and see problems?

Im sure it would help narrow it down.

Yes, just look for a dent are bad groove cut in the sealing surface on the tip. They will most likely have a slight ring around them which is normal, just make sure its not deep are overlapping.

Theres also an edge filter inside the tubes. If you've ever had bad fuel you might consider changing them anyway.
I found a set from "injectors" for 260 for a set. Says they are brand new bosch with o rings. Sound like a good price? Like you said even if they aren't the problem it needs new ones cause i know they are the originals with 102k on them and had the injectors out 5 times. Id say they are long over due.
Pretty fair price. I get them a little cheaper but I also spend over 200k a year with these people.

Might check with Jeff at Mumau Diesel, hes a cummins dealer in PA. I buy a lot of things from him as he knows his parts. Its just easier and more convenient dealing with him as long as your not in a hurry for the part.

If i have time to wait for the two days to ship he gets my business!!
I'll check that place out. I tried the injector kill test and drive it. The truck missed so bad and had a lot less power i couldn't tell any difference. One kinda good thing happened when i got home tho. it started randomly missing at idle. once every 10 sec it. It didn't have the pop sound it was just a slight miss. So i got under the hood and started wiggling all the wires that had to do with fuel sensors nothing changed. Got in the cab and watched the fuel rail psi gauge on the CTS. It was bouncing every where like 4.6,5.0,4.7,5.0,5.2,4.5 the bam! 3.2, 4.7,5.0 and so on next time it done it it went to 2.9. This leads me to believe it is the sensor on back of rail, sensor on cp3, cp3 its self is bad or a bad wire. what do you think about the kind of sporadic rail pressure?
Pull your FCA plug and see if it maintains max rail at idle.
I just did it. Rail went to 29kpsi and truck started loping
I changed rail pressure sensor and its still the same. I took it for a little drive it and it was missing a lot more than normal. When it first started it was just a miss here and a miss there. It is much worse now. On my drive i also seen the rail go 0.0kpsi for a split sec two times.
Just changed FCA on cp3. No luck missing and popping much worse at idle now.

Rip if it was a wire do you think it would throw at least one code? And if it was the connecting tubes it would white smoke and be hard to start?
Checked the injector return and it was too high. Sent injectors off to get tested and waiting for results.
Took efi live off, Put all brand new Bosch injectors in it with new connecting tubes. Now it just pops every once in awhile. Any ideas?? The new injectors seemed to help it
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