6.4 clattery engine, MFD Pid fluctuating

bigfords · Jan 25, 2016

I've got a pretty difficult 6.4 that I've been working on.
My issue is that after you fire the truck up, engine sounds good and runs smooth. After about 30 seconds to 2 minutes or so, the engine all of a sudden changes sound and runs real clattery. Something changes. It sounds like it is high pressure fuel related, like the timing or fuel rail pressure ramps up.
While monitoring all the fuel pressure related parameters, the only thing that looks strange to me is that the Mass Fuel Desired pid is not s smooth line, but is a bouncing between the 0.16 to 0.30 gr. If I run RPMs up to 1100 or so, the Mass Fuel Desired pid smooths out at 0.16 gr or so and is a straight line.

Any input? Truck was recently purchased and the owner does not have a lot of history on the truck. #8 injector looks like it is on its way out also, misses at idle.
Truck has GH tunes and is ******d. Has Industrial Injection Phat Shaft turbos on it.

thanks much!
Rich

78f100 · Jan 25, 2016

It's most likely a injector, if it's to that point do not run it long. It could easily ruin a piston, rod, or block. If 8 is failing start there.

bigfords · Jan 25, 2016

How so? Over fueling? It does not seem to be over fueling but I could be wrong. Would it be a nozzle issue?

I'm also concerned about a couple small traces of metal in the fuel, up at the secondary filter housing.

Powerstroke Man 6.4 · Jan 25, 2016

How would you find out if a injector is going out? STFT?

webb06 · Jan 25, 2016

Watch this video
http://youtu.be/wkaA7OyPqDg

Is this what the truck is doing?

This truck was in our shop a couple years ago. We couldn't find anything out of the ordinary, besides the obvious smoking and missing, so we got ahold of the ford tech line and they told us the truck needed a hpfp replacement. The truck would only do this on the first start up of the day on a cold morning and only if you let it sit and idle after starting. If you immediately took off and drove the truck it never did this.

Customer opted not the repair and to this day he is still driving it like this and it occasionally comes through the shop for other repairs. Says it still does it in the winter if he lets it idle on a cold morning.

Sent from my iPhone using Tapatalk

bigfords · Jan 25, 2016

Wow, that one is really bad. It definitely does not do it to that extent, but I would say maybe the beginning stages. I know #8 is misfiring, just not sure if thats the only problem. I'm afraid it may need an entire high pressure fuel system.

78f100 · Jan 25, 2016

I have had several with only one bad Injector do as you are describing. Also had some with cracked injector cup or bad sealing washer do the same, letting compression gas in the return fuel. These fuel systems do not like air anywhere in the system. If cylinder 8 is known bad and missing most likely that's your problem. There are lots of issues one bad Injector can cause.

78f100 · Jan 25, 2016

Powerstroke Man 6.4 said:
How would you find out if a injector is going out? STFT?

I use the ids cylinder contribution first. Then relative compression. Can also look at cylinder misfire info, and several other tests to help confirm. He said 8 is misfiring already, 7 and 8 are the most common cylinders to be damaged and the most common injectors to fail as they are used the most because of the regen process.

bigfords · Jan 25, 2016

78f100 said:
I have had several with only one bad Injector do as you are describing. Also had some with cracked injector cup or bad sealing washer do the same, letting compression gas in the return fuel. These fuel systems do not like air anywhere in the system. If cylinder 8 is known bad and missing most likely that's your problem. There are lots of issues one bad Injector can cause.

Ok good info. Whats your experience with any metal in the fuel? The only ones I've ran across needed injection pumps. The truck runs fine going down the road, but idles rough.
Also, any chance there could be an issue with the nozzle? The previous owner said that he supposedly already replaced #8 injector, but swapped the old nozzle onto it since it was a 30% nozzle.

78f100 · Jan 25, 2016

I have never had a issue with a nozzle, imo it's highly unlikely it's a nozzle issue but is possible I guess. How much metal was in the fuel bowl? And what color was it? Sounds like you have a decent scan tool, if your using ids or snapon you can run a hpfp test. It will give you a good indication if you have pump issues, it ramps pressure up in stages so you can see desired pressure vs actual.
Does cyl 8 pass buzz test when it's skipping? Is it smoking white when the skipping starts? I had one a while back with a bent pin on the harness plug at the rocker box. It would skip sporadically mostly when cold, no smoke just a dead miss. Someone had bent it in the past, I assume as the plastic plug warmed up the connection got better but when cold it was hit and miss. That one was kinda tough to find.
I'm certainly not trying to sound like I know everything but I have had a few head scratches and want to help you figure it out.
Edit if everything with injectors checks out, you can start it with the valve cover off and watch the valves it could be a lifter failing also.

footlong70 · Jan 25, 2016

If your lp fuel system is stock, I wouldn't be surprised if the metal came from the hp pump. Logic would say that metal shavings couldn't have made it through the frame filter/pump (unless the lp pump was piling up which Ive never heard of) from the tank up to fuel bowl/filter. If the shavings came from the hp pump then its very likely to have some in the rails/injectors.

bigfords · Jan 26, 2016

78f100 said:
I have never had a issue with a nozzle, imo it's highly unlikely it's a nozzle issue but is possible I guess. How much metal was in the fuel bowl? And what color was it? Sounds like you have a decent scan tool, if your using ids or snapon you can run a hpfp test. It will give you a good indication if you have pump issues, it ramps pressure up in stages so you can see desired pressure vs actual.
Does cyl 8 pass buzz test when it's skipping? Is it smoking white when the skipping starts? I had one a while back with a bent pin on the harness plug at the rocker box. It would skip sporadically mostly when cold, no smoke just a dead miss. Someone had bent it in the past, I assume as the plastic plug warmed up the connection got better but when cold it was hit and miss. That one was kinda tough to find.
I'm certainly not trying to sound like I know everything but I have had a few head scratches and want to help you figure it out.
Edit if everything with injectors checks out, you can start it with the valve cover off and watch the valves it could be a lifter failing also.

Its not a terrible amount, but in my experience any amount is bad. I'm using IDS, used to work as a diesel tech at a Ford dealer. I appreciate the help, nice to have someone to bounce stuff off.
Before the engine gets clattery it doesn't smoke much, but then gets smoking whitish blue smoke when clattering and missing on #8. I'll check on the buzz test, havn't tried that yet.