Stuttering on top end

[Rmartin-97]

I got my truck back together and have about 2800 miles on it so far. And the other night while getting on it I noticed it stutters right about the shift point like it bounces almost like a rev limiter. It's holding 23-24k on rail psi at the point it does this. It almost resembles the valves floating but it has rcd valve springs. It throws no codes or nothing. Does anyone have an idea what else I could check. Could an injector going bad cause this?

 

[6.0 Tech]

What rpm are you at when this happens? It could be in the tuning.

 

[Rmartin-97]

3400-3500 it don't do it free reving only under a load.

 

[6.0 Tech]

Is it a intermittent issue or everytime you get on it

 

[Rmartin-97]

Is it a intermittent issue or everytime you get on it

It's intermittent. And don't do it on the lower tunes

 

[sootie]

what is your fuel pressure on the low pressure side

 

[6.0 Tech]

I think that it could be tune related, but check base fuel pressure too like sootie said.

 

[Rmartin-97]

I havnt checked low pressure fuel. But of its dropping wouldn't rail psi drop?

 

[6.0 Tech]

You would tend to figure so but it could be putting small air bubbles in and its too slight of a drop that the monitor doesnt catch it.

 

[6.4 Stroker]

Have any other tunes you can try?

 

[Rmartin-97]

Have any other tunes you can try?

Just the ******** set I've had for four years.

 

[6.0 Tech]

So this is something new then? Or have you just not driven on this tune this way before?

If its something new i would definitely be checking for a failure instead of tuning. I was under the impression that the tunes were new...

 

[Rmartin-97]

No same tunes I've had for years. All the injectors were flowed about 3 months ago by rcd. Could the hpfp be going bad?

 

[6.0 Tech]

In theory yes, i wouldstart with base pressure though. If possible i would also make it happen when doing a power balance tosee if an ijector is dropping out.

 

[Rmartin-97]

I also noticed today my trucks surging under wot now that it's cold. Is that a symptom of a bad hpfp?

 

[sootie]

What's rail pressure doing when it surges?

 

[6.4 Stroker]

:whs:
Also, VGT move freely?
I've seen them do some funky things when they lock up.
I think you best shot is gonna be to try to duplicate the problem with an IDS so you can look for irregularities. Nothings worse than throwing money at something that might be the problem.

 

[Rmartin-97]

I still haven't got to test the low pressure fuel. But I have noticed when it's stuttering it starts smoking worse. The rail drops to around 20k. And when I go to a lower tune it don't do it at all. And the issue seems to be worse when the motor is hot.

 

[Jbird]

I have this problem but i have a small exhaust leak at the manifold so i figure it was related. Mine seems to only do it at mid throttle 3 or 4th gear. I have an sct so no way to monitor rail pressure. Seems fine under wot and isnt a very hot tune either


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[Rmartin-97]

I tore into mine last night an found my plug in my rcd manifold is leaking so I'm fixing it to.