Severe misfiring and poor idle after MDS delete

[narshbox]

2014 Ram 1500 5.7 8-speed. Roller bearing failed on cylinder 5 lifter which subsequently destroyed the cam. I ended up replacing the lifters and cam with non-mds versions from Mopar (camshaft p/n 53022314AD, lifter and carrier assembly p/n 05038784AD). MDS solenoids removed and plugged. ECM calibration updated to disable MDS.

When I first started the engine after repair, it was misfiring and wouldn't idle for more than about 10 seconds. There was also a pinging sound (sounded like pre-ignition). Later I discovered that I had misaligned the timing mark on the crankshaft by literally one link. At this point I was concerned that the pinging sound may have been the valves hitting the piston. There is more history here if it helps: https://www.ramforum.com/threads/vvt-solenoid-keeps-going-bad.181286/post-3039675

Problem: I have since corrected the timing chain alignment. No more pre-ignition or other bad sounds, but the engine is still misfiring and won't idle for very long. The only remaining code is for a random misfire.
P0300 - Random Misfire Detected (SES, Pending, Current, History)

Here is a screen capture from the VCM scanner during a startup: https://youtu.be/O3CtoQaV77s

Cylinder 6 seemed to be the worst offender for the misfire so I put a borescope in the combustion chamber and it appears there was no valve-to-piston contact so I do not suspect any bent valves or pushrods at this point. See pics below.

May be a clue that there is a lot of soot on the spark plug (see pic) - those are brand new plugs I just installed.

Thanks for any help on this. I'm stumped at this point.

Exhaust valve:


Intake Valve:

 

[jws123]

You need to tune the truck not just tune to disable mds It needs to be tuned to run on a non MDS cam or it will run rough I had this issue years ago before I worked on alot of hemis. Also have you done a compression test?if so what where the results.

 

[Sillygoose]

check your pushrods?

 

[narshbox]

Thanks for the suggestions. I did the compression check on cylinder 6 last night and the results are zero compression. Literally the needle didn't move. I thought at first my guage was bad or had a leak but I checked it with compressed air and it is registering and storing pressure until released. It was also tight in the spark plug hole with a good o-ring. If it's right, that would mean a gross opening, like a stuck open valve, vs. a head gasket leak.

Then it occurred to me that the valves may not even be in the correct positions (see previous pictures of cylinder 6). The piston is at near TDC which means both valves should be closed on compression stroke, or both slightly open during overlap on the end of the exhaust stroke. That intake valve is clearly all the way closed.

I'm going to pull the valve covers tonight and see if the pushrods are dorked up. I checked them when assembling but maybe I missed something.

 

[crackerjack1957]

Thanks for the suggestions. I did the compression check on cylinder 6 last night and the results are zero compression. Literally the needle didn't move. I thought at first my guage was bad or had a leak but I checked it with compressed air and it is registering and storing pressure until released. It was also tight in the spark plug hole with a good o-ring. If it's right, that would mean a gross opening, like a stuck open valve, vs. a head gasket leak.

Then it occurred to me that the valves may not even be in the correct positions (see previous pictures of cylinder 6). The piston is at near TDC which means both valves should be closed on compression stroke, or both slightly open during overlap on the end of the exhaust stroke. That intake valve is clearly all the way closed.

I'm going to pull the valve covers tonight and see if the pushrods are dorked up. I checked them when assembling but maybe I missed something.
View attachment 573319

Pushrods or bent valve stems.
Rods fell out of lifter if you're lucky.
Unlucky then the pushrods or valve stem bent with the incorrect timing you already confirmed.

 

[EdGs]

........Then it occurred to me that the valves may not even be in the correct positions (see previous pictures of cylinder 6). The piston is at near TDC which means both valves should be closed on compression stroke, or both slightly open during overlap on the end of the exhaust stroke. That intake valve is clearly all the way closed.

I'm going to pull the valve covers tonight and see if the pushrods are dorked up. I checked them when assembling but maybe I missed something.

In your pic, the intake valve is closed, bit the exhaust valve is open.

Will be interesting to see what you find out.

Good luck. Hope it's an easy fix.

 

[narshbox]

Pushrods or bent valve stems.
Rods fell out of lifter if you're lucky.
Unlucky then the pushrods or valve stem bent with the incorrect timing you already confirmed.

Pulled the valve cover on the passenger side. On the first checkout, all the push rods were seated in the rocker arms - intake and exhaust. There was no free play on any of the exhaust rockers except cylinder 2. This is odd as 4, 6, and 8 should not have exhaust valves open/opening all at the same time. An important note too is that cylinder 2 had no misfires (see video above of VCM scanner).

I then pulled the exhaust rocker assembly nice and slow, loosening each bolt a couple turns at a time. Felt like there was spring tension being relieved little by little meaning I don't think the valves were stuck, but rather spring compressed by the rocker arm.

Here is a pic of cylinder 6 exhaust valve (previously seemed to be stuck open) after removing the rocker assembly - Valve is fully closed. I put the scope into each cylinder to confirm that all the exhaust valves were indeed closed with the rocker assembly removed. Based on this, I don't think I bent any valves, at least on the passenger side.



None of the push rods were stuck, they came right out. None were bent. I also inspected the ends for any signs of damage and there was none:



At this point, it does seem like maybe the push rods were not seated in the lifters. I tried to check this after I pulled the rocker assembly. They did seem to push further into the block and "click" into the lifter, but it was too hard to tell if they were like that before the rockers were removed, or if they just pulled out a little bit when I pulled off the rocker assembly.

Any ideas/thoughts on this are much appreciated. There doesn't seem to be a smoking gun here, so I'm not sure what else to do but try to reassemble carefully and try to run the engine again.

 

[diymirage]

Is the cam installed at the proper timing and not 180 degrees of?

 

[crackerjack1957]

Pulled the valve cover on the passenger side. On the first checkout, all the push rods were seated in the rocker arms - intake and exhaust. There was no free play on any of the exhaust rockers except cylinder 2. This is odd as 4, 6, and 8 should not have exhaust valves open/opening all at the same time. An important note too is that cylinder 2 had no misfires (see video above of VCM scanner).

I then pulled the exhaust rocker assembly nice and slow, loosening each bolt a couple turns at a time. Felt like there was spring tension being relieved little by little meaning I don't think the valves were stuck, but rather spring compressed by the rocker arm.

Here is a pic of cylinder 6 exhaust valve (previously seemed to be stuck open) after removing the rocker assembly - Valve is fully closed. I put the scope into each cylinder to confirm that all the exhaust valves were indeed closed with the rocker assembly removed. Based on this, I don't think I bent any valves, at least on the passenger side.

View attachment 573338

None of the push rods were stuck, they came right out. None were bent. I also inspected the ends for any signs of damage and there was none:

View attachment 573339

At this point, it does seem like maybe the push rods were not seated in the lifters. I tried to check this after I pulled the rocker assembly. They did seem to push further into the block and "click" into the lifter, but it was too hard to tell if they were like that before the rockers were removed, or if they just pulled out a little bit when I pulled off the rocker assembly.

Any ideas/thoughts on this are much appreciated. There doesn't seem to be a smoking gun here, so I'm not sure what else to do but try to reassemble carefully and try to run the engine again.

Well if #6 has no compression the intake/exhaust valves are not opening.
That would mean it's the pushrods.
Meaning they were not seated in lifters .

Leak down test is more accurate on this......tells you when the valves or rings are leaking.
If not losing air on the intake & exhaust valve stroke would show(sound of air on I/E side)which valve is not opening.

No leak down tester......you go by sight & feel compared to the other working valves .
Check for broken valve springs also

 

[narshbox]

I'm happy report she's purring like a kitten. No ticks, no knocks, no pre-ignition, no misfires, and no codes!

After carefully reinstalling the exhaust push rods and rocker arm assembly on the passenger side, I regained compression in cylinders 4,6, and 8. I also pulled the rocker cover on the driver side and turned it over a few times - Everything checked out on that side. Put it all back together and its finally running right.

I believe the misfire readings on cylinders 5 and 7 were some kind of misreading by the computer. Maybe the crank speed was off on those fires due to the lack of compression on the other cylinders?

Lesson learned - Never rush through a job like this. And check everything twice!
Many thanks to everyone for all the suggestions and ideas. You guys are awesome! And crakcerjack1957 - you nailed it!

 

[jws123]

9 times out of 10 missfires after engine work ona hemi is a push rod issue ahah glad it worked out.