Need help.. possible lifter/cam

[ChuckL333]

09 Ram 1500 w/5.7 replacement engine misfire

Sorry for the long post but I'm totally lost.. I'll start with a little backstory.

Bought the ram 3 years ago, high mileage (200k). Had no issues the first year then started throwing a P301 code under a heavy load around 4000 rpm. Changed plugs, coil packs and injectors and nothing fixed it. Always P301.

Drove it for 2 years like that with with the misfire no issue and finally decided to have a shop diagnose the problem which I assumed to be a bad cam/lifters. Low and behold that's what the problem is. From what I know they ran a vacuum test and it was obvious to them without a doubt that was the issue.

So that brings me to today.. just had a used engine (120k) installed that was 'gaurenteed' to be working and it is having the same issue. The same DAMN issue down to the cylinder and the RPM's the misfire is occuring at - almost like they were never swapped at all.

What are the odds the new/used engine is bad with the exact same issue? What else can I check? Electrical? Bad sensor?

 

[pacofortacos]

Slim and none and slim left town.

If you want to be sure, pull the valve cover crank it and watch that cylinders rocker arms move, if they move the same amount as the other cylinders then chances are the cam is ok.
Can do a compression test.
To me it sounds as if it is spark or fuel, but it is going to be hard to guess at if it only happens under heavy load and around 4000 rpms.

You might try closing the plug gap up another 10 thousands and try that - if it is weak spark that might help to cover that problem - but for diagnostic troubleshooting, try it and see if it changes anything at all.

Might even be something as stupid as a corroded ground somewhere.

 

[ChuckL333]

Slim and none and slim left town.

If you want to be sure, pull the valve cover crank it and watch that cylinders rocker arms move, if they move the same amount as the other cylinders then chances are the cam is ok.
Can do a compression test.
To me it sounds as if it is spark or fuel, but it is going to be hard to guess at if it only happens under heavy load and around 4000 rpms.

You might try closing the plug gap up another 10 thousands and try that - if it is weak spark that might help to cover that problem - but for diagnostic troubleshooting, try it and see if it changes anything at all.

Might even be something as stupid as a corroded ground somewhere.

Did a compression test on the old engine and it was good. Cylinders next to it identical.

I can see a bad spark, but wouldn't a corroded ground cause a random cylinder misfire and not just p301?

It's at my mechanic right now who doesn't typically do internal engine work. Thankfully it is my cousin so communication is good. What can I recommend him to look for?

The last engine I had was tested at 4000 rpm. I have no clue what tool or test they did but they could see it losing vacuum at them RPM's.

 

[Burla]

So you didnt use your cousin mechanic for the engine swap. Sounds like you got played. Sorry to hear it.

 

[ChuckL333]

I had a local shop with the right equipment diagnose the truck. They claimed bad lifters/cam. Got myself a used engine and had my cous do the swap (different shop). Same issue still.

I have no problem if the issue lies somewhere else I just want to figure it out. If I can fix it at this point at least I set the odo back 100k. I'm not even sure where to look at this point.

 

[HEMIMANN]

The odds are far higher with a used engine, let's put it that way.
We here have recommended only a new or factory reman for this reason.
It's a shame FCA hid the issue. Lots of engines could have been saved otherwise via the wisdom of this Forum.
Best of luck to you.

 

[Burla]

I had a local shop with the right equipment diagnose the truck. They claimed bad lifters/cam. Got myself a used engine and had my cous do the swap (different shop). Same issue still.

I have no problem if the issue lies somewhere else I just want to figure it out. If I can fix it at this point at least I set the odo back 100k. I'm not even sure where to look at this point.

did you obtain the failed cam and lifters? pretty important to verify.