Hi, I’m having trouble with my engine that is hard to rule out.

2000 Ford F450 with 7.3L and 4R100. 198k miles. Stock, studded.




Backstory:
I rebuilt my motor about 750 miles ago. It ran great for about the first 500. The injectors were re-used, but are only about a year old. They’re full force remans. The other day I started noticing that after warming up the truck, when in drive it had a intermittent “clacking” knocking noise when hot. Shortly after I noticed that the engine would buck under mid throttle accompanied by the noise. The noise is a “clack” noise that you can hear under the truck the most, mostly when hot. I retorqued the injector hold downs, which had loosed up some but the noise and lack of power continued to be intermittent, showing up while warm. I went to a shop and had him run his scanner on the truck. I will upload the results there. Let his recommendation I replaced injector O-rings on the passenger side (this is where the nocking was apparent). Now the knocking is constant when hot and cold, and I have a major lack of power and a new issue to where I will give it throttle and the engine will put off a “leaking fluid noise” or a “sh sh sh sh”. Probably not the best description, but the truck won’t accelerate while it’s happening. So, now the truck doesn’t have the power to drive, at least hot.

You guys have any ideas on what’s going on, or the next step to test? At the moment I don’t have a scan tool available.

 

Any thoughts?

 

High pressure oil issue? unplug the ICP and take it for a drive.

 

I took it for a drive and it starts and runs fine cold - no issues, no noise. When it starts acting up, in-plugging the ICP doesn’t help.
at idle I get 500 PSI at 10%DC.
at WOT I get 2750 PSI at 38% DC.

I did get some balance codes though..
coldish 5 and 7 came up, but when warm 3 and 8 were present. I have the dark purple colored CPS.







Thoughts?

 

the point to unplugging the ICP is to start it that way so the computer has to use a stored table for ICP values.
but since it acts up once it is at operating temp, you might be having electrical side injector issues.

 

3 and 8 unbalanced is quite common. I think you'd have better luck posted in the 7.3 forum here. @Sous can probably move it for you.

 

Working on it sir, thanks for the heads up and hopefully we can get Trgglynn some help.

 

Thread moved to the 7.3L PSD forum...

 

I believe the high low open bank codes point to the IDM or UVCH but im rusty on those exact codes

 

What’s your thoughts on 5 and 7? I poked around with a stethoscope under the driver valve cover and around the block and manifolds. I believe the “clack” is coming from the passenger side. It’s weird that they “disappear” on the contribution test when the problem comes up.

 

I was wondering about the IDM.
the UVCH and gaskets are a year or so old. They could be old, but I am doubtful to it. Could the IDM make the injectors fire inconsistently or half-work? Or would it be more like they stop working right all together?

 

There are people way better than me that are going to help you through this....way better.

 

I appreciate your input.

 

Update:

I swapped fuel injector 5 and 7 out for some Alliant Remans that were unknown in condition, problem persisted.

I hooked up a fuel pressure gauge to my truck and was only getting 20 psi at idle. I recently changed out the fuel pump, so I just swapped out the fuel bowl as I had a spare. This took care of the fuel knock and idle issues. Truck still is running sub par and now ONLY cylinder 8 fails cyl contribution. Perhaps I trashed #8 with low fuel pressure considering its last in the firing order?

 

Here's a bump for you.