Possible Injector Problem

[windrunner408]

Ok a little back ground info. Back in the summer of 2010, I purchased my first tuner it was a SCT SF3 with canned tunes. I had a magnaflow 5in exhaust (turbo back), AFE intake, and CFM+ large mouth elbow kit. When I installed the performance tune, my mileage went up considerably to over 18mpg hand calculated with mixed but mostly hwy driving and I could run 3-4 psi of boost at 70 mph. Then that fall I did a RR kit, egr delete, spearco intercooler, updated stc fitting, oil cooler delete, and modified the exhaust to a stack. Ever since then my truck has not performed the same. I now run 8-9 psi of boost at 70 mph and it kind of feels like it just doesnt have the power it used to. I have tried different tunes and still the same results.

Last summer, I did head studs with all new dummy plugs, stand pipes, seals you name it and a new HPOP with new IPR valve and still the same. I also have upgraded my FICM to a 58v unit with IDPs flash and if anything this mod has made it worse on the cruising boost but definitely helped with low end torque and response for sure.

So I am wondering if it is possible to have some bad injectors that just arent sending any fuel to the cylinders?? The funny thing is is that the truck runs and sounds GREAT. While probably not probable, IS it possible to have two bad injectors that simply arent firing and they be on the opposite side of the motor such that the motor runs smooth, kind of like a V6 vice a V8?? Any thoughts would be appreciated.

 

[hawgdoctor]

What does your fuel pressure look like with the RR at full throttle?

 

[windrunner408]

I have the RR set to ~60psi (it is a little above 60 when cold and settles out at like 58 psi when the truck is warmed up) and at WOT the most it will drop to is like 56psi. I have never seen fuel psi lower than 55psi ever. I have it monitored at the filter bowl.

 

[patrickke]

Do a contribution test

 

[windrunner408]

Yea that is my next step. i was just curious if such a condition could exist.

 

[patrickke]

It could but I had an issue with my last set of injectors (not Jesse's) and the truck would romp bad so I don't think it would run that smooth... Have you tried putting the truck back to stock on the tuner and seeing how it runs?

 

[hawgdoctor]

It could but I had an issue with my last set of injectors (not Jesse's) and the truck would romp bad so I don't think it would run that smooth... Have you tried putting the truck back to stock on the tuner and seeing how it runs?

^^ This. I know I've got a couple thet are sticking pretty good now when cold, and it sounds like a over cammed big block when it lights off. Can tell when it's there when warm too because it isn't that smooth anymore cruising down the road.

 

[windrunner408]

Ok well it runs smooth as silk even from startup. So I am going to rule this situation out. I put it back on stock tune and it runs really good. I would say slightly better than just a regularly stock vehicle. The only downside being that the boost at cruising is higher than I would like 8-9psi at 70mph.

 

[hawgdoctor]

Honestly those boost numbers are about normal. that's where mine usually sit too. I wouldn't be concerned about that.

 

[patrickke]

Have your tuner tweak your tunes a bit

 

[windrunner408]

Ok well I found out that I dont have the ability to monitor IPR duty cycle with my CTS. Not sure if i can monitor that or not if I data log with my SCT SF3. Anybody know??