lonewolf42262

Ok I decided to go ahead and mod out my 98 12 valve with the following mods
HTTB 62/14 turbo, ground 100 plate, 4 inch straight exhaust, and 370 marine injectors, and a S&B intake kit. The plate is pushed full forward and the afc housing is as well, I have not modified the afc housing in any way. After I installed all of these mods the truck is running funny, starts just like normal but both at cold eng temps and normal operating temps there seems to be a miss around 1600 to 2100 rpm, you can hear it thru the exhaust. Insteand of a constant drone its kinda choppy. I purchased a 3gsk and a snow stage 2 kit also, but have not installed as im still trying to diagnose this problem. When under load the truck runs well floor it and the turbo spolls quick and hits 45lbs of boost with ease. I have checked for boost leaks, and fuel leaks I cannot see any evidence of either, but I have pressurized the intake system yet to be 100% on the boost. But I am assuming this is a fuel problem. I am very happy with the egts as they are controlable I can pass 12 with easy at WOT but I knew there was now way around that, the snow kit will keep things in check for my purposes. I have heard of problems with 370 injectors but my 97 runs great on them. When cold there is a bit of whitre smoke when you stab the throttle in netural, as well as a jump so to speak or a miss. I am not sure if this is timing related or somewhere else. Thanks Jesse

SPLnut

370's tend to smoke more at idle and may miss in higher rpm's...Bump your timing to 15.5-16 but no higher as your maxed on boost and about to throw water at it...Head gasket may not last much longer with out studs or o-rings

300sd2500

You need to stud and oring her before she pops, especially with the water injection kit. Take it from me, I am going through that process now.

lonewolf42262

I am heading the warning about studs, but I just spent 3k in mods and studs will have to wait, thats my biggest reason for a larger turbo and water and meth, ie keep foot out of it for the most part and have more power and lower egts while towing. Twins would have done that also but for what it would have cost me it just was not exconomical at the time. I still belive there is actually a problem not related to the injectors, my 97 has 370's and no problems like I have in this truck I dont know if its more pronounced with the big turbo or what. I am currently saving for studs and a o-ring setup. Do you have to remove the motor for a o-ring set-up??

SPLnut

What trans does the 98 have?

300sd2500

No, you oring the head.
Maybe you have an unmatched 370 injector. Try changing them around and see if it does it on one of the other cylinders.

lonewolf42262

It has a 5spd, when the motor is cold and in netural if you stab the throttle it has a poping noise in the exhaust and blows white smoke. I will see about changing the injectors. Keep it coming Jesse

300sd2500

You need to check your timing. I wonder if it has slipped.
White smoke is raw unburned fuel.
Its a good idea to bump your timing to 15.5*-16.5*.

TxDiesel007

In agreement here

i run 16.5 currently with dragonflys, and used to with 370s... i need more timing with the dragonflys, but with the 370s it was great....

Rick

lonewolf42262

timing was a issue I was concerned about, guess its time to start studying as soon as i fix my 5th gear nut again lol

SPLnut

Also check your fuel pressure...could be time for a new over flow valve...And 15.5 to 16.5* timing would help...

300sd2500

Good call on the overflow valve. Do a search on here for the test. Its something like pinch the line and if the rpms jump up its either good or bad (dont remember off hand)
Infidel always posts on this one.
Marty Tompkins at precision diesel has overflow valves the cheapest $35.
Do a search for him to.

allisfarmer

not enough fuel maybe??? do you have an aftermarket lift pump like a fass or airdog?

lonewolf42262

Ok I'll check over flow valve tonite, no I don't have a additional lift pump, I was under the impression that with my mods it was unnecessary.

Txwelder

I know this one is old, but Im jumping in. I too have the same noise coming out of the exhaust in a specific RPM range. I have tried to ignore it but I was on the phone with a fellow CTD owner while driving and he asked me what that noise was? Said it sounded like a helicopter was hovering over my truck. That is the best way I can describe it. At WOT or at least giving her a good bit of throttle, it doesnt do it, but at low rpm and lugging it sounds real bad.