I recently had new injectors installed under GM's special policy on my 2003 GMC. After driving for a few weeks now, it seems it doesn't have the same power it had before the injector change and the fuel economy has gone down ~ 1 - 1 1/2 mpg from what it was previously. Has anyone had this happen after an injector change and will the power and fuel mileage return to what it was in time? I assume the dealer did a reflash on the ECM when the injectors were changed. Would this have an affect on power and mileage. I run a Bully Dog Triple Dog usually set on Performance full time(before and after injector change).

Thnx,
BB

2003 GMC Crew Cab D/A
Bully Dog
AirRaid Intake/Filter
4" Flo-Pro Exhaust
275-75R 16's
Currently 298,650 km's (185573 miles)

I recently had new injectors installed under GM's special policy on my 2003 GMC. After driving for a few weeks now, it seems it doesn't have the same power it had before the injector change and the fuel economy has gone down ~ 1 - 1 1/2 mpg from what it was previously. Has anyone had this happen after an injector change and will the power and fuel mileage return to what it was in time? I assume the dealer did a reflash on the ECM when the injectors were changed. Would this have an affect on power and mileage. I run a Bully Dog Triple Dog usually set on Performance full time(before and after injector change).

Thnx,
BB


X2 and have been wondering the same thing

yep been there . more than likely they updated your ecm when injectors were installed. mine went from 16 to18 mpg to 13 and no power. check your intake tube for a hole and all fittings . you can try and take it back ,but they will say that there is nothing wrong that they can see. i have been working on mine got it to 18.875 on hwy 16.538 city.
check and make sure your waste gate is working. mine was stuck open. and i have done a couple of mods from here. and that has helped.
brian:cool:

have the same problems I don't really know alot about duramax but where is this located and what should I look for. I can tear a DT 466 apart in my sleep but haven't even started to work on my D-max thanks in advance Mike

My truck has had injectors also and it is really sick, still gets good mileage just no power. I just changed all the filters again and still down on power? How do i go about checking out the wastegate? I recently installed a edge juice with attitude monitor and on the highest level it still has no where near the power my other two trucks have. Any suggestions?

there are several places you can start to diagnose a problem like that (down on power). first, check for codes. presuming there aren't any i would check and see if its holding rail pressure (you'll need some sort of scan tool to do this) during acceleration first. you can also check the restriction in your fuel system by using a kent-moore gauge connected to the test port on the front of the engine (schrader valve). at idle it should be between 3 and 7 InHg.

as for testing your wastegate, just disconnect the air line from the actuator and connect to to a REGULATED line from your air compressor. turn on the air compressor and leave the regulator turned down. as you raise the regulator pay attention to when the wastegate starts to open. hopefully someone will chime in with the PSI that is supposed to occur on a stock turbo as i can't remember but i would guess somewhere in the low to mid 20 psi range. if the wastegate is stuck open it won't move and if it opens way to early that's a problem too.

I've had injectors replaced on my duramaxes before and i've always had it run better afterwards, not worse.

It has only been about a week since I had my injectors replaced, but I was also concerned about my lower mpg and not as much power. I have a ppe set on level 2. I was expecting the truck to get improved mpg and power. I havent hand calculated yet, but I know that my gauge is way down from how many miles that I have traveled. When I fill up, I will post what I got.

Same thing here. I had injectors replaced a year and a half ago, and mileage went from 19.4 to 17.0. I've tried the Edge Juice on setting 0 (stock) and 1 (mileage), and while 1 has better power, the mileage is about the same as far as I can tell. I'm looking for other options for better mileage, like K&N air filter, maybe? Does anyone who has one know?

when i put my K&N air filter in, my mpg raised about 2 mpg. but then it went back down quite a few months later. the issue you might have with them is over-oiling. i have done this before, unknowingly, but now that i know, it doesnt happen. now for the fact that i threw it in back of my seat and bought a new NAPA filter instead. you realy dont gain all that much from it, but you have a lot to lose, i guess.

Ken

as for testing your wastegate, just disconnect the air line from the actuator and connect to to a REGULATED line from your air compressor. turn on the air compressor and leave the regulator turned down. as you raise the regulator pay attention to when the wastegate starts to open. hopefully someone will chime in with the PSI that is supposed to occur on a stock turbo as i can't remember but i would guess somewhere in the low to mid 20 psi range. if the wastegate is stuck open it won't move and if it opens way to early that's a problem too.

I've had injectors replaced on my duramaxes before and i've always had it run better afterwards, not worse.

I am also having issues with my 04. I had the dealer check my wastegate here is how they explained it to me. At 30 psi it should start to move, meaning you should be able to unhook the lever if need be. At 45 psi the rod should have moved 0.25 inch. Hope this helps.

a stock lb7 wastegate will open long before 30psi. 45psi will explode the stock turbo in a hurry. i think the numbers are wrong or perhaps they weren't talking about a LB7 turbo?

I am also having issues with my 04. I had the dealer check my wastegate here is how they explained it to me. At 30 psi it should start to move, meaning you should be able to unhook the lever if need be. At 45 psi the rod should have moved 0.25 inch. Hope this helps.

When you say 30 PSI and 45 are you talking Absolute or Gauge?
(Absolute being 14.2 +/- atmospheric, plus boost or Gauge (Boost) being Absolute less atmospheric.)

My MAX gauge pressure is around 21 stock, 23 with the PPE on level 3, the PPE reads 36.9 absolute. That seems to indicate to me that the waste gate opens around 24 boost psi or 37 absolute??? I even put juice grips on it to see what that did, no effect with PPE on level 3, but jumped stock up by 2 PSI max. (This is with the PPE boost valve as well). Not sure what all this means.

On the topic: I noticed a drop in milage after getting mine replaced. I wonder if it has to do with rail pressure, by-passing too much fuel, thus not burning all the fuel it was designed for, thus less power, more milage?
I say an increase in performance with mine. Go figure.

I'm having horibble issues with my 04 dually, i rescently had all my injectors replaced and now i have extreamly low power. I keep getting a p2227 code on my banks pda wich stands for barometric preassure sensor, i think that might be the problem buti cant be sure. I took my truck to my bud over at ppe and even he was baffeled. hetried diagn. my problem but came up empty. I didnt have that code pop up before the injector change, so im taking my baby back to the service dept. i hope they dont rape me too much....



04 dually, 4-1/2 inch no muff. turboback
banks six gun tunner, fat head waste gate, speed loader, power pda
k&n cold air

:mad: