my boost gauge is pulsing, like the waste gate is stuck open, its strange, it bounces right thru 10psi to 30psi. Is this common on these new trucks? my 12 valve never pulsed unless i hit 40psi. then it would bounce a bit.

 

I dont think yer wastegate is open or you would never hit 30psi

 

i understand that. but i don't understand why its pulsing so much? boost leak, bad gauge? whats the deal.

 

OH man only one thing I know of that will do that....... but first a few questions
1) How is it running? Rough, lopey, popping noise in the intake or exhuast?
2) Hard to start no power?
If none of the above then check all your plumbing to the guage! Where are you getting your signal from?

 

seems to run ok, gauge plumbing should be fine i tapped into the intake with a boost bolt from genos. i chose the second bolt in twards the front of the engine i do here a ticking noise especially when it lugs, it shuts off vialent. what do you think it could be?

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also if i run advanced timming with the smarty it pops if you run it thru the rpms in neutral.

 

How do you feel about pulling the head? If it's something you can do easily I'd take a look at the valves. Did you adjust them lately? Maybe take a look under the cover first!
Quick check to see if you dropped a valve seat! the pulsing is caused by air being pushed back into the boost flow at the wrong time like a bad exhuast valve hung open.
Others will chime in I may be wrong it's happened before!

 

It very well could of happened when i over reved it. I will try to get some tools togeather this weekend to check the valve lash. i am mechanically inclined but very busy with work dont really have a place to do the job. so im hoping the valve lash is out bad enough to affect the gauge...not bad seat. if it is a dropped valve is this covered on my warrenty from cummins? shes only got 56000 miles on her!

 

I think it to old to be under warrenty? 5yr or 100000? Icould be wrong

 

Ya, i think so too. Im hoping its the gauge or something else is messed up. It seems steady around 10lbs of boost, and gets worse with hard throttle, if you keep it a@ 10 lbs @50 or so mph steady throttle it does not flicker a bit, but when you hammer it it starts flickering. the truck starts up fine still seems to have good power, it does have a little bit of a tick to it, maybe thats the way they sound, its the only common rail i have owned and driven in regularly other than the ones i test drove. maybe ill sell it and get somehting different...

 

That's your problem, right there. A gauge from that source will flutter, sometimes wildly due to pressure waves created in the manifold by the intake valves. Source it from somewhere else, intake horn, turbo outlet, whatever and the problem will disappear.