well i got the 4.5 last night and there in but now my engine wants to studder really bad when ever i put the hammer down with my chip on 5x5 if i turn it down to 1x3 its not as bad but still there. When my engine is cold it idles great but afer its warm and i have been puttin the hammer down then it has a slight miss to it. It allways did when its cold out but now its a little worse with these injectors. You guys got any idea what might be worng? is my injection pump on the way out? when i bought the truck it has 0 psi of fuel pres. when i first put my chip on it. now it never goes less than 7 psi so i dont think thats the problem.

 

Did you check for codes? Sounds like you are running low on Fuel volume....possibly a bad FP gauge?

 

That was my thought too..

Just wondering if you used a torque wrench and torqued the injector lines to 28-29ft/lbs? Are the copper washers new or smooth? 89inch/lbs on the injector hold down bolts?

Maybe valves could use some adjusting.. Grounds and t-tap good on fueling box, connections good overall..

Bad load of fuel? I can always tell when i got crap fuel when the idle gets a little rough.

It does sound like the bigger inj's are just amplifying an issue that was already existing before the change though.

Just some thoughts..

 

the FP gauge is built into the juice with att. and when i turn my key on to start it it reads 0 or 1 when its idling it reads 13-15 and the lowest i can get it at wot is 7 to 8. To me that seems like its working ok. It does seem like its running out of fuel and kind of spitting and spudering im just not really sure what it could be. if im a little lighter on the gas then it seems to run ok.

 

my check engine light never came on. i dont really have a torq wrench but by guessing i would say the injector lines are at least 30 fl/lb probably a little more. and i tightened the injector hold downs (well just the front bolts i didnt touch the back ones) to about as tight as they felt when i took them off maybe a little bit more if anything. It doesnt look like any of the injector lines are leaking. and the coper gaskets came with the new injectors and so did o rings for the injector. and i made sure the copper gaskets came out with the old injectors too. I never had a problem with my chip before the injectors so i would think thats grounded/taped ok.

i wiggled the valves by hand and there was some free play in them all except the one that had a valve open at the time. i would say about .008" to .016" if i had to guess but i didnt check them with a feeler gauge. I did also find some soot in the intake but it was just between my grid heaters and my head. But i would think if the valves were that bad wouldn't i have noticed it before the injector install? I know they need addjusting every once and a while i was planing on doing that when i put my head studs in.

 

I agree with other fuel a FASS IMO when running big injectors. Also are you sure it's not the clutch slipping like a wildman?

 

Im not 100% its not at least partly my clutch but its allmost inpossible to tell because it runs so rough when i put the hammer down. but to me it feels like the engine is cutting out / studdering not so much free reving like when a clutch goes out in a gas engine.


The best way to discribe what its doing is its like at random some of the injectos are only putting in about half to 1/4 of the fuel they should be. but it seems irratic and there doesnt really seem to be any regularity to it like it would be just half the injectors are defective or somthing.

the fuel has to be getting in there cause it dont take long to get my EGTs up to 1500 deg.

 

Have heard of several people having poor ground connections on their fueling boxes causing something similar to what you are describing.. Might want to double check the connections.

Dont want to send you on a wild goose chase or anything, but a poor connector will sure do that. Since you say its sometimes rough at times of lower fuel demand it MAY not be fuel related..

But then again, it could simply be running out of fuel at high load.

 

your running out of fuel, My truck did the exact same thing. You will have good pressure but when you try and run that much fuel on stock fuel delivery it runs it's dry. It took me putting my truck on the dyno to find out I was dropping about 30 HP with my box on 5x5 vs 4x5. And I only have mach 1.5. I would say invest in a FASS 150 you will never run out of fuel.

 

thanks for the replies so far. One thing im confused on is i though as long as you had at least 5 psi of fuel pres. then that was enough. I though i herd of people having hard starting with too much psi. So even though i have 7 to 8 psi you think i need more? i just put that vulcan big line kit on and put the pump back by my fuel tank so i would rather not buy a hole fass system.

Is there a pump i can get to bolt in place of the stock one that will give me more flow with our redoing everything? Or maybe should i get that vulcan draw straw? do you think that will help any?

 

there may be pending codes that havent turned the light on yet

 

As far as your FP, It may be reading positive but you don't have the quantity to feed your big injectors when you are WOT. It seems it is just like mine was, I was fine with the box on 4x5 but on 5x5 it wanted that much more fuel that I didn't have to give it. My truck is set up with the FASS pump by the tank. There are cheaper pumps that will do the same thing. For example the Holley Blue.

 

i just checked the codes and there is nothing at all which is suprising since my cam sensor went out not to long ago.

well thanks for all the help. I guess i will try changing my fuel filter just in case, and check my juice with att. conections and see what hapens. If that dont do it ill get me a bigger fuel pump.

 

you need the volume as well as pressure, when hitting flat out horsepower runs like that.

 

If your ground is weak, your egt gauge on the juice will not function properly. I just posted a similair problem with a buddies truck. For some reason on his setup, it only shudder around 26 psi boost. Does yours shudder immediately when you go WOT or does it happen after some boost hits the motor. Will it shudder in 3rd gear if you mash it or just 4th and 5th. I think that fuel is a wild goose chase at this point it is probably clutch or wastegate blowing open.

My friend's problem started after upgrading from RV 275's to Jammer 5's. I have just a holly blue mounted to the stock wiring harness on the frame and idle is 16 psi, WOT never below 10 psi when fuel is hot and never below 13 psi when fuel is cooler.

I would first off buy a 1/4" pipe plug to entirely disable the wastegate and then if it still has the problem, wire the wastegate actuator shut. This way you can tell for certain that it is not a fluttering wastegate.