New motor. Running rough

Dzchey21 · Nov 29, 2014

no i would love to know your experience with that. Would be a first for me

02bigstrokin · Nov 29, 2014

The 08 I had when I rebuilt the motor I did the same thing as the op and reused the hpfp and I used a set of unknown condition injectors. Motor ran perfect for the first week and then one day I drove it to work and all was fine, cut it off waiting on boss to open gate, maybe 10 min later I started it back up and it sounded odd. Went to take off to park in the lot and about ran him over as it lunged forward. Parked the truck and checked codes on dash daq... Nothing. Came out at lunch time and went to drive to store and truck had no power, rattled, and then when I came to a stop and put truck in park it free reved to about 2k rpms and back down. I even checked for codes with solus scanner and still nothing. So I'm sitting there trying to figure out how I was getting home and for some reason I hit clear codes on dash daq and I swear the truck idled down and ran perfect. I could drive it wherever I wanted to go at full power, everything perfect until I cycled the key. Then it started over again. Next morning started truck in driveway and it smoked white some on start up. I figured no big deal at least if it's an injector I'll find it easy enough with scanner. Nothing. All contributions perfect. Then I noticed the rail pressure would flat line at 5k psi on dash daq while it was acting up. Clear codes and rail would fluctuate like normal a few hundred psi a idle. An injector will not flat line rail pressure like that. Last ditch effort I dumped a couple bottles of fuel conditioner in tank and ran it for a few days. About the fourth day after this whole scenario started I cranked truck one morning, clear the invisible codes and it never came back after that. I chock it up to a sticking valve of some sort in the hpfp. To the op, give it a shot. Won't hurt anything to try. Without a scan tool that's about all you're gonna be able to do anyways.

Dzchey21 · Nov 29, 2014

cool, thanks for sharing i have never heard of that before.

Lmgrpowerstroke · Nov 30, 2014

Thanks guys I appreciate the help from both of you

Lmgrpowerstroke · Nov 30, 2014

02bigstrokin. What was your rail pressure normally

Dzchey21. What should regulator pressure be at idle on the pump

02bigstrokin · Nov 30, 2014

It fluctuated around 4500-4750 or so at idle. I could watch it on the dash daq and it would always be moving around until it messed up those few days and it stayed dead on 5k until I cleared codes.

On a side note I thought at one point it might be the rail pressure sensor in the fuel rail but that wouldn't make any sense because sensors don't usually "fix themselves" after going bad. That's why I pointed at hpfp.

02bigstrokin · Nov 30, 2014

I asked about the heads earlier because we had one at work the other day that we rebuilt the motor on due to hpfp coming apart and holding injectors open and melting two pistons. Took the heads to a machine shop and they decked the heads and did a valve job. Well I always wondered why ford says the tolerance for machining on these heads is like .004. Put the motor back together and started it and it was obvious we still had a dead hole. After a while of trying to figure out what the hell went wrong, we found on number 7 cylinder the intake valve was never fully closing. Between however much he decked them, the valve job sinking the valves up in the head a little, and tolerances in the lifter, pushrod, rockers and bridges it was too tight. Had to actually clearance a rocker bridge to get more tolerance. Started truck all is well. Put valve cover back on and truck ran perfect. Weird things do happen.

drunk on diesel · Nov 30, 2014

we don't make a habit of it, but when budget constraints dictate it, we shave the tips of the valves to get geometry back in line

Lmgrpowerstroke · Nov 30, 2014

Little update. I ran the truck for about a hour today. I had to cycle the fuel pump on 3 times to get it to start. It stopped revving up when putting it into gear. Rail pressure at idle is at 5800 It seems like it's still has air in the system when it's idling some what

sootie · Dec 1, 2014

are your cam and crank sensors plugged in securely?

Lmgrpowerstroke · Dec 1, 2014

Yep already double checked all wiring

Lmgrpowerstroke · Dec 5, 2014

Dzchey21 said:
well unfortunatly your going to have to narrow down what cylinder it is for sure. Either a power balance test with IDS or auto enginuities or let it get bad enough to throw a code. But the next step once you find that will be to swap in a new injector. Or swap from one cylinder to the other and see if it follows the injector. There is always a possiblility that you have low compression on the one cylinder from say a bad valve job or a pushtube not seated correctly ect.

So I got it hooked up at the dealer everything check out normal. All injectors are firing normal.

Came up with that it is a balance issue.

Idles at 5-600. Rev and it goes away get to 1k rpm it comes back and then goes away again above that rpm.

Dzchey21 · Dec 7, 2014

Like a balance issue as in harmonic balancer or flex plate? Or injector balance?

Lmgrpowerstroke · Dec 7, 2014

Like flex plate or harmonic balancer. Truck has stock flex plate. And ATI balancer

Mike@MPD · Dec 7, 2014

Sounds like something behind the flex plate

02bigstrokin · Dec 7, 2014

Did u take that adapter off on the back of the crankshaft? Arp makes shoulder bolts to be able to line that back up properly. If it was removed it's hard to get back correct without shoulder bolts