P0300 Running rough after cam and lifter swap

[stc315]

My 2014 Ram 1500 5.7 had wicked lifter knock and has 135k miles so I swapped out the MDS cam and lifters and all of the valvetrain (springs, locks, retainers, pushrods, etc.). I also put MDS plugs in place of solenoids. I had previously added a Diablo Sport Diablo 87 tune and shut off MDS. Now upon restart, engine won't stay running unless I keep the accelerator pedal down (about 1/4 throttle) and dies when I let off. It runs very rough and I get P0300 multiple misfire code. I also added new spark plugs. I have no idea where to start. I double checked all connections and have no fluid leaks I can see. Background on my skill level, I'm a mid level mechanic (basic diagnostic skills on muscle car era engines). I have good mechanical skills though (remove and replace). I made sure I kept the timing chain tight and the timing marks all lined up when I added the new cam. I kind of wonder if I have a vacuum leak, but can't find anything not connected. I did notice a hose that runs along the drivers side of the intake manifold that's not plugged into anything but can't find anything to plug it in to.

 

[crackerjack1957]

If you are sure timing is correct then the rocker arm assembly & or push rods were probably not installed correctly. Pull valve covers & check to make sure all valves are opening the same amount.
If not pushrods are probably bent.

 

[stc315]

I checked them before closing top end up. Put brand new pushrods from Mopar and checked them before install.

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[stc315]

Here is a picture of the hose I mentioned.

 

[crackerjack1957]

I have a 2014 5.7, will see if I can locate when I get home this evening.
Is this on the drivers side at the front?
How does engine run if you plug the line?

 

[stc315]

Thank you. It's on the driver's side above the fuel rail. I haven't tried plugging it up. I will try it when I get home later.

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[stc315]

I tried capping the line and no change. Still won't run without giving it throttle and it runs like crap. Can also smell fuel smell from exhaust (unburnt fuel). It's driving me crazy. I should note that rough running started when I replaced MDS sensors with block off plugs. I just thought my bad lifter gave up finally (when I took it apart one of the lifters was galled up). I also found the number 1 cylinder exhaust bolt was broken (put new bolt in after swapping out valve springs). Everything went back together smooth with no issues. Checked all the electrical connections again and everything was tight.

 

[crackerjack1957]

Was not able to lift hood on truck due to snow to check vacuum hose.
Will try again today.
Thinking you have another problem though if you plugged line off & have same issue.

 

[stc315]

Update:
Pulled the pass side valve cover and found to problem causing the missing. 3 exhaust pushrods were not in the right hole (were in crevice by valve cover rail, my son put that side in and I didn't double check his work). So got it started and running. But now I have super loud lifter knock again coming from passenger side. Going to pull valve cover again and check for pushrod play. I'm thinking maybe I have a bad rocker arm or bent pushrod. Fortunately I have the old pushrods if one of the new ones got bent. Other thing that concerns me is that I might have hydrauliced a rod by running it with three exhaust valves not opening properly. It appeared that the valves were slightly open though when I discovered the problem. Out of daylight, will start working on it again tomorrow morning.

 

[stc315]

Update and closure:
Opened up valve cover and noticed that #4 exhaust rocker was misaligned and somehow the edge of the rocker was under the washer for the center bolt on the rocker shaft (feel like a dumbazz!!!). Loosened up the rocker shaft bolts, realigned all 4 rocker arms and retorqued bolts. Buttoned it up and fired her up. Had lifter noise for about 3 seconds until oil pressure came up and it faded away. Running perfect now. Engine has lots of power again. So relieved it was something simple to fix.

Should hopefully get another 100k miles until I have to rebuild bottom end lol. That'll take me just over 2 years and she'll be paid off by then. Either trade her in for new truck or build a blown stroker for her lol.

Special thanks to charonblk07 for posting the 4th Gen Cam Installation thread!!!

https://www.ramforum.com/threads/how-to-4th-gen-hemi-cam-installation.82531/

It was a huge help!!!

 

[Tach_tech]

Glad you got it figured out. That hose you were wondering about is just a vent line for the transfer case or transmission, can’t remember exactly which one.

 

[huntergreen]

Good to hear it was a simple fix.

 

[Raymond Jahnsen]

Did the valves still open when the rocker arms were pinched under the washers? I’m having pretty much the same issue and have checked everything. Compression and all and checked to see if the valves were all opening and closing correctly and they seemed to have been. But I didn’t look to see if I had that issue with the rocker arms.


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[Trader40]

I know this thread is older but it was very helpful. If you get the PO300 code after a cam and lifter swap check the push rod alignment first. if i do another one, i will be turning the truck over before the valve covers go back on.

 

[Tach_tech]

I know this thread is older but it was very helpful. If you get the PO300 code after a cam and lifter swap check the push rod alignment first. if i do another one, i will be turning the truck over before the valve covers go back on.

Should always turn the engine over by hand at least twice anytime you mess with cam/crank timing or any valve train components.

 

[James OBrien]

Update and closure:
Opened up valve cover and noticed that #4 exhaust rocker was misaligned and somehow the edge of the rocker was under the washer for the center bolt on the rocker shaft (feel like a dumbazz!!!). Loosened up the rocker shaft bolts, realigned all 4 rocker arms and retorqued bolts. Buttoned it up and fired her up. Had lifter noise for about 3 seconds until oil pressure came up and it faded away. Running perfect now. Engine has lots of power again. So relieved it was something simple to fix.

Should hopefully get another 100k miles until I have to rebuild bottom end lol. That'll take me just over 2 years and she'll be paid off by then. Either trade her in for new truck or build a blown stroker for her lol.

Special thanks to charonblk07 for posting the 4th Gen Cam Installation thread!!!

https://www.ramforum.com/threads/how-to-4th-gen-hemi-cam-installation.82531/

It was a huge help!!!

It's not difficult to mis-align pushrods on these during re-assembly, after many off and on evolutions trying to get mine set just right I ended up putting a dollop of assembly lube in the rocker arm cups, that seemed to keep them in place finally while tightening things down.

 

[James OBrien]

Should always turn the engine over by hand at least twice anytime you mess with cam/crank timing or any valve train components.

Amen on this, saved me from really screwing my engine up!

 

[dbstotty65]

that hose you couldnt find where it goes is your transmission vent, it doesnt plug in anywhere