6.0 Long Crank, Rough Idle when cold.

[Buffalo444]

Alright, so this issue has been going on since I got the truck, but has been getting slightly worse lately and after a little diagnosis I am somewhat stumped.

Truck details:
2006 6.0 Auto
251k miles
stock besides cat/muffler deletes
New HPOP within last 2k miles
New GPs/GPCM at the same time

Ok, so here is what it does... It cranks for 5-7 seconds after sitting over night before firing, then runs a little rough and smokes white until you drive it. I usually let it idle about 3 minutes, because if you don't let it idle it barely has enough power to pull onto the road from curb parking (it actually has stalled a couple times) but when it is running like that, it will barely move but then will suddenly have full power and run normally like flipping a switch. I saw a video about diagnosing it to see if it was a HPO leak or the HPOP, or the ICP sensor, but after cranking it it fired after it saw 500 psi like it should (just seemed to take a while to build pressure) stuck around 30% IPR duty cycle at idle, and only hit 78% duty cycle on a WOT run while hitting 4000psi ICP pressure. ICP desired/seen seemed to stay close enough while running, nothing more than a few PSI away from what it wanted. The only thing that seemed off is that the ICP when sitting was at 0 PSI, which seemed odd because supposedly should show at least atmospheric pressure? I don't know, I'm stumped and I don't want to throw parts at it.

 

[Buffalo444]

Oh, and it throws no engine codes, except one for cylinder 1 GP circuit open.

 

[fordfreak4life]

You should only be around 18-20% on the ipr at idle, I would say you have a hpo leak but does it start fine hot?

 

[Buffalo444]

Yeah when its hot it fires right up, barely even needing to crank before firing.

Should I run it up to temp then check my IPR %?

 

[Buffalo444]

Morning bump.

 

[yannie]

Your next step is probably a leak down test. Check out "dieseltechron" on YouTube. There's a video for almost every problem with a ford diesel.


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[Buffalo444]

Oh thanks! That is actually the guy I saw the first video from, but it was embedded in a much older thread.

 

[78f100]

What's ficm voltage? If power is coming on like a switch once warmed I would check the ficm.

 

[Buffalo444]

I don't really know if I would consider it "warm", it's after no more than 3 minutes of idle time. But I will check it as soon as I get off work.

 

[Irontx]

My IPR duty cycle is about 30% on cold start..... idle is bumped up...then drops to about 24%... I would lean towards injector stickage/damage.

 

[Buffalo444]

Would it make sense for the power to come on all at once then?

 

[Buffalo444]

Your next step is probably a leak down test. Check out "dieseltechron" on YouTube. There's a video for almost every problem with a ford diesel.


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https://www.youtube.com/watch?v=LTBo541gqg0&list=UU6s_EctGCrqClSIThpSicJw

Is this check where he pulls the ICP sensor the leak down test you are talking about?


In one of the comments he says:

The wear would be enough to be a no start hot if it was driven hard and shut off and restarted within a few minutes. It still should be the same diagnosis on early ones. Listen to the injector preclatter for sticking injectors and make sure it has oil staying in the filter. (Wrong cap)

If I have the wrong cap/filter and it isn't holding oil, could it be backflowing through the HPOP and losing all of the pressure? Or could it just be that the HPOP doesn't have the feed it needs until the LPOP has been turning for a while (hence the long crank) to build pressure? But if that were the case isn't there a low oil pressure lamp or something on the message center?

 

[Buffalo444]

Just checked, when the dealer I bought it from (not a Ford dealer) did the oil change they used a Napa filter, or at least the Napa filter cap *facepalm*

 

[Irontx]

The wrong filter will starve you for low pressure oil feeding the hpop. .. and no.... no sel for low oil..... I've blown them up with no codes... lol....

 

[Buffalo444]

Well good thing I have a motorcraft filter and cap coming with my 5w-40 amsoil. Lol

 

[Buffalo444]

Well, would rather be safe than sorry so I got a new cap and filter now, installed and went for a 40 mile drive. Will check back in in the morning to let everyone know how it starts.

 

[Buffalo444]

Ok so the filter and cap helped a bit. Now it takes about 2-3 seconds to crank and fire, and doesn't have the lack of power and need to idle. It still runs slightly off at first and stutters a bit, but doesn't take nearly as long to get up to full power.

 

[yannie]

Did you do your testing in the morning? How was the FICM voltage? 0 psi on ICP would mean a bad sensor. The ICP can fail and show no code but the truck shouldn't start at all if that was the case.


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[yannie]

I'm thinking it's a bad injector that's not showing a code. Sticks when it's cold and works good when warm.


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[Buffalo444]

Did you do your testing in the morning? How was the FICM voltage? 0 psi on ICP would mean a bad sensor. The ICP can fail and show no code but the truck shouldn't start at all if that was the case.

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Yes, had been sitting overnight. FICM voltage was all good, 47.5 volts at the lowest, normally 48.0-48.5, didn't drop when cranking or anything.

I'm thinking it's a bad injector that's not showing a code. Sticks when it's cold and works good when warm.

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So I unplugged the ICP sensor to see if that was part of the culprit... it helped... somewhat. The truck cranked for 3-5 seconds every time, started better but didn't have the hesitation (as bad) that it did. Seemed to have helped until one morning I started it, put it in gear and it stalled out immediately... so I plugged it back in and not much changed.

I put Rev-X in it about 50 miles ago. It has smoothed out a little, but it still has the stalling problem and a still that slight bit of hesitation it had, but not nearly as bad, like the on/off switch like way it did before. Just the other day, I had it stall, restarted it and revved it up to 1250 rpms for a second then put it back in gear and it drove away fine... I'm pretty well stumped at this point. It got a new HPOP before I got it... could it be IPR related? or does Ford install a new IPR with the HPOP?