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6.7 missing/ popping... i need some help

23195 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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I done a cylinder balance test with a snap on scanner and it all came back good all cylinders were 100% equal even when i would drive it and get it to miss. on my way home again today i got P0107(map sensor) i forgot all about the map sensor on the back side of the pusher intake. So i gave a little tug on the plug and it slid off the sensor!! I put it all the way back on and went for a drive. I got it out on the high way going up a big hill in 5th and let her have it. Of course started missing but not as bad i don't think. It didn't jerk as bad when it missed and i have to really lay into it. No more missing at idle tho. i did notice rail psi was around 22k going up the hill. i don't think that's low enough to make it pop like the rail is going dry do you? Also after i got into it hard another time it through the p1507. crank case restriction. I have about a four foot hose coming off the valve cover venting into the atmosphere. crank case filter has less than 15k miles on it. any more ideas where to look? I wanna look over everything before i take the injectors out and get them tested. Thanks for the help!!
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I also have a mechanical fuel pressure gauge from the fass to the cp3 and it drops from 16 to 15 psi under wot. I cant decided if its a fuel issue or electrical...???
what more information do you guys need? Give me stuff to try and ill do it! would a connecting tube cause this? I'm going look under valve cover tonight and check over injector harness. I have reused the tubes about 4 or 5 times but I don't know what a bad one looks like. Any help would be great!
Thanks for the replay! Crank time is normal. I know it idles around 5-6kpsi. I will shoot the manifold tonight and record the rail when i crank. I did remove the valve cover last night. Checked all the injector wires and Ithink the connecting tubes are fine casusethere is no fuel in the oil. i checked over all the sensors and grounds making sure they were all plugged in. so after all of this itook it for a drive just to see. It had one slight miss to it when i slammed into it going up a hill. which is much better than what it has been. drove for another 5 miles and tested it again on a hill. NO miss at all. stopped at a buddys places and stayed for 15 mins. on the way home it missed just like it did a few days before. you get it under a load and it has a few hiccups. its not a dead miss at all and the truck still has great power
When I start it the rail spikes to 16kspi then levels to 5.1-4.9kpsi. I didn't have much time to shoot the manifold temp but here is what I got. cold they were all 56-57 deg. after I few sec I got CYL#1-60 CYL#2-62 #3-62 #4-60 #5-66 #6-65 after a min or so.. CYL #1-65 #2-70 #3-73 #4-67 #5-76 #6-70. had to leave for work after that. I can get a better one tonight if needed. so now I know #1 is little cooler and #5 is a little warmer but I don't think its that much of a difference do you?
Is any time its under a load or heavy throttle. Right around 55% throttle and up. The more rpms it goes the more it misses and pops. Sometimes a little puff of black will come out when it does it. It runs pretty clean other wise. Also no boost leaks or blow by. Motor was fully rebuilt under 10k ago. It hasn't missed at idle since that one day It all started.
i just noticed something.. if you roll into the throttle really slow the rail stays around 26-27kpsi. if you keep it up there it dont pop or miss. but if you really slam into it and keep it on the floor when the turbo is trying to spool it will start to jerk and do its normal thing. but the rail is still around 23kpsi. never below 22k. to explain the pop it is almost like a back fire maybe? this really makes me think fuel prob but after i got into it fast and made it jerk a few times i went to go around a turn and was like 15-205 throttle and it did 2 little light jerk and misses.. im really at a loss on this
Stock cp3. I have 60% exergy nozzles in it but they tuned the injector duration down so it would hold rail. Fass stays at 15-16psi. Its not boost activated. I'll see if a full tank helps tonight. It doesn't sound or feel like you turn the key off at all. Its def more like a pop or backfire.. I'll check all the plugs on the cp3 and the fuel fail sensor tonight and let you know what I come up with. I did put a beans fuel sump in it the night before it started doing this but I don't think it has anything to do with it. I really appreciate all the help!!
All is well on the sump. Got the fuel level down to an 8th and filled it all the way up. Still the same. I have some more info for you that's odd. Driving home in the rain tonight it was popping/missing happened more often than it was. It would do it just normal driving. It wasn't as violent in the lower rpms tho. If you hold the brake and give it a good amount of fuel it seems to do it more. Also any time it pops louder a small amount of black smoke comes out the stack, just a quick puff.

I noticed something else very odd on the drive home. I looked at my edge cts insight and thought i seen the rail pressure drop then come back up. So i watched it really close with the truck set on cruise control. Rail was around 8k and would all of a sudden drop to like 3.2k and shoot back up to 8k. I caught it doing it around 4 times on the way home but it never missed or popped when it would drop. CTS messed up or think its accurate? Its only a mo old.

After i got home i checked all plugs and wiring on the back of the rail and cp3. All looked well but couldn't check out the wires that well cause they are all wrapped up. ! followed them as much as i could. I hope this helps!!
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I done a free rev to 3k and it is smooth the whole way. I revved it up slow and got into it fast still no miss or pop.
If the tubes were leaking would it leak fuel in the oil?
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
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.
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?
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.
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?
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?
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