I've always said that something wasn't 100% with my 2000 truck since i bought it and now it seems to be showing its ugly face with the increased boost and fuel added by the chip (and my right foot).

I thought i had a very slight miss when i first bought the truck could here a ever so slight whoompa in the exhaust pipe. Now i definately have a whoompa noise coming from the intake, you can really hear it when you pull the air filter right through the turbo.

Question is, any idea whats causing it? Bad valve? Piston? I seem to have the same power as before, no smoke, boost seems the same, no heating problems. I just finished towing my trailer a couple hundred miles @ 75+ MPH, boost was pegged at 15 PSI pretty steady, i did hit EGT's of 1100 a couple times but the duration was under a minute.

Idea's?

When it starts going whoom pa-pa you're in trouble. ;)

How does it run? Rough? I have a feeling you might have a bad RPCV (rail pressure control valve) A bad one causes it to idle with small surges.

Are you German by any chance?

Runs fine, tough to tell but maybe a slight miss at idle, not surging any different than it did before yet, always did do a fast surge when going into reverse but not very often.

RPCV? I'm not familiar with this, what is it and where's it located?

German? Hell no! Canadian through & through and like my rice beer & whiskey!

OK, i've also just noticed something, i used to get about 3-4 PSI when sitting still holding the engine @ 2000 rpm, now 0 on the gauge, punching it will still make it hit 5 PSI.

Hoot fergits and talks CUMMINS, and sometimes DMAX, here on the PFI (that's Primitive Fuel Injection) 6.5 forum! ;)

And, if you ain't GERMAN, the whoom pa pa could get to be very annoying, particularly when the accordian starts playin'!

But, crack the injector pipes one at a time, till you sync the noise to the cylinder, see which one is goin' Bavarian on ya! :cool:

gmctd

Any educated guess's on whats going on?

My understanding, is that if you have an intake valve problem, you will be able to hear it and even feel a 'pulse' if you put your hand in the path of the intake. Same with the exhaust, a sticking or weak seat on an exhaust valve will have a similair effect in the exhaust, which I think is what mine has.

1rst you'll need to determine which cylinder is the culprit - crack each injector pipe to find it.

If any of the pipe fittings are wet before you start, that cylinder(s) will be getting less fuel than the others, can cause stumble\ light miss.
Check the Inj Pump fittings, also.
Tighten to cure.

Once the stumbling cylinder is found, pull all the glow plugs, do a comparison compression check - should all be 400-425, no less than 375, but all within 25psi of higher reading.

Crank up pressure, leave compression gage connected for leakdown check, will find valve leak or piston ring seal leak.

If all ok, then it is probably fuel supply - could be that tubing fitting\ one-way valve at the Inj Pump, since you've recently replaced injectors.
Or, a severly crunched injector pipe, back under the intake manifold.
Or, you got another low output injector.

If not ok, pull valve cover, check the nylon keepers are not crumbled, measure valve lift at problem cylinder, compare to adjacent cylinder.

Do this on push-rod side of rocker arm, then on valve stem side, to determine if cam is flat, lifter is collapsing, push-rod is worn, or rocker arm pivot surface is worn.

If all proves out, but still low compression, then the head on the offending bank will have to come off

Ooops.... I picked this up in "Active Topics" Sorry.

Overlooked TDG's post - that is correct for leaky valves, where you'll feel compression whoof thru any damaged valve.

Woofing getting worse on the way home, hope she holds together for awhile here, no time to park it just yet.

TDG i have sent you 2 PM's in the last couple of weeks, are you not getting them?

Pull intake and crank it up. Try to pin point cylinder. Broke valve spring can also be culprit to add to the list.

Yep - broke valve spring, skewed rockers with crumbled nylon keepers, collapsed lifter - all will give a 'ticking' or 'tapping' noise as indicative.