Miss when warm
 

Hey guys. This is my first post on the forum and appreciate any insight. One of my service trucks is a 2007 f550. The truck has a "reliable" miss when warm. When I say reliable I mean that it misses the same exact way every day. When the truck is not up to operating temperature it will rev in park flawlessly through the rpm range. After it reaches operating temperature there is a miss around 1800 rpm and 2200 rpm. On the road there is no miss when the engine has a load on it but only at very light throttle. Press the skinny pedal down a bit more and it goes away... I have had 3 different Techs look at it. One is an independent shop and the other two were from Ford but neither of them can come up with anything. I am also a technician(not a vehicle tech) so I am familiar with how to diagnose problems and dont really feel that they are doing anything more than trying to throw parts at it.

Just so you know, the ficm and injector harness are new. The ficm is a 58V unit from BPD. HPOP is new. Turbo is also new. The miss was there before the upgrades so these changes made zero difference in the symptoms.

Have any of you seen anything similar? Could you help me steer one of the Ford techs in the right direction? Thanks!

Likely what is happening is hot stiction. Most think of spool valves when they hear the word STICTION.
What is going is the intensifier piston is sticking a little bit. You can go the additive route of just replace
that injector. The additives are not a fix where an injector is. BUT before throwing an injector at it find
someone to put it on the Ford VCM2 with IDS and run the power balance test. Be warned that the
AutoEnginuity's® will not show you the bad injector. The software for some reason they have not
addressed just does not show marginal injectors like it should. it can show a sick one as being ok.

Get the truck scanned and look at the contribution for each injector in the uncompensated mode.
Make sure that the truck is up to temp when they run the test.

The reason to test is to be sure you get the correct injector. I would also have the fuel pressure checked.

How ofter do the fuel filters get serviced and with what brand filters?

Following Sean's comments.

I've used my IDS to hunt and find a cold stiction injector and that was easy.

I spent hours looking for an injector fault when I was told it was, but it wasn't. But what I learned is the hot un-compensated results can vary quite a bit and I never sorted out the why or where. I was trying to hunt for an injector with a ticking noise when very hot soaked. But when using the IDS I could get the injectors to be perfectly level in output, and then sometimes vary. It was maddening. So I can understand where even with the IDS an injector problem can't be identified by a service person, especially if they are concerned about the hourly costs.

Unfortunately, that means the tried and true A-B testing. One new injector, round-robin through the 8 locations. That's a lot of work and hopefully, you don't get to that point.

One of the more experienced with injector issue people on board may chime in with better methods. When all else fails I tend to go A-B.

The person running the test needs to use the FDR ( Flight Data Recorder) option in IDS along with
contribution waveform recording to really get some good data to look at after the drive.

I am not sure if some of the free and low cost apps that work with the OBD2 ELM devices can
do a long recording or not..

Looking back and seeing that your having the issues at 1800~2200 might be a problem with
watching the power balance contribution waveform do to the rapid changes that it will under go.

Can you get it to misfire in PARK holding the throttle steady? IDS can be setup to hold the RPM at
a given number. It will be a a lot more stable then trying to use your foot to hold it. If it will do it then that
makes it a lot easer to read the waveform and also check other things at the same time.

That is why data logging (FDR) with the waveform recording can be handy. It's all in the time stamp of the
event.Find the event and then take it's time stamp and look at the other data points in that time frame.
Something may jump out. When it gets down to it there is the possibility that this is not an injector issue.

I hope you can get something from all my jumping around and general rambling. This comes from thinking
way faster than I can type and then having things jump into my thought train. Things like "Oh I should say that too."
All of this and my general wild train of thought.

How many miles on the injectors (sorry in advance if that has already been posted)?

The injectors have about 25k on them now. All ford injectors replaced at the same time.

I had one of my guys take the truck back to the dealership on friday. The same symptoms were occurring when they hooked it up to the IDS. They did a uncompensated balance test and this time, however, its quite obvious that 2, 4, 6, and 8 are missing. My guy said that 4 and 6 appeared to be the worst offenders. The tech said they would do a pressure test as he thinks it may be the stand pipe. I updated the stand pipes, dummy plugs, new oil pump, new oil cooler, ficm, etc at the same time the injectors were done.

All this work was done because i bought a dead truck chassis, replaced the engine with a reman long block, and did all the updates with the hopes of not getting back inside the engine for several years. Hasn't worked out too well so far!

It does seem to me that it might be oil related since it only misses when up to temp but I'm really no expert. Any ideas? Im on the schedule for friday to take it back in. What should i have them do besides the pressure test?

Thanks again guys!

All even side. First thing to do is to unplug the injector connectors. Take a look at the pins and the plug it back in.
I would then fallow the harness back to the FICM side to be sure there are not any crushed spots in that harness.

Then you may want to pull the rail and check it for crap. Also check the top section of the stand pipe and be sure it
clean and free of any debris. Also while the rail is off check the top of each injector to be sure they are clean.

All it would take is a bit of towel in the body of the upper section to hang up the valve in there.


https://cimg6.ibsrv.net/gimg/www.for...e2b8a349d4.jpg. https://cimg7.ibsrv.net/gimg/www.for...c478a5142f.jpg



https://cimg5.ibsrv.net/gimg/www.for...37e4045cab.jpg
This is why it takes so long for an air test to blow the oil out of the rails.

That little check valve lived inside the top half of the stand pipe. It's there to help lower pulsation from the injectors opening and closing. (Or at least I think it might help)
It also makes it harder to blow the oil out during an air test.

If an injector on the drivers side was leaking combustion gas into the fuel rail, it would/could take out all injectors on that side. The 6.0L banjo bolts have check valves to protect the other bank.

Not saying this is what happened, but it is something to think about when you have multiple injector failures.

I am wondering about the health of the passenger side injectors w/ the symptoms described.

Basically you remove the fuel filter and the valve in the center. You then fill the bowl with fuel. NOTE: You can leave the valve in place at first to see if your getting bubbles. If you are then you can take it out to isolate the sides.
You then have someone crank the engine with the starter solenoid wire and look for bubbles in the fuel bowl.
If you see bubbles they you remove the glow plugs from that side and put one in at a time and crank. That
will tell you what one is the issue. But don't stop you want to do all four on a side.

The reason for removing the valve in the center of the bowl is you can see what side the bubbles are coming from.
There is an opening in the bottom and it's split in half. One goes to the left and the other to the right side. So bubbles
coming from one side that go away when you pull the glow plugs should show up when you put the plug in the bad
cylinder. You test the rest just to make sure that it's not more than one injector having issues.

I will find a video to attach to this in a bit.


Here is a good test.



Here is a failed test, It can take a little bit sometimes.


Also Anthony started out here. His nick name is . run6.0run