JustACobalt

iTrader: (1)

if you have seen my other thread, i dropped a valve and nicked the piston a few months ago. since then i got the engine rebuilt a few days ago and the car is running a bit rough.

around 1500-2000 rpm while cruising it studders, it almost feels like its misfiring but no codes at all. i checked the plugs to find ngk bkr7es-11 which seems to be totally the wrong plug for a high boost lnf. anyway they were gapped to .041-.042 so i tightened them down to .036 and the studdering is still there. i dont recall it doing this before it was rebuilt with the same plugs. would getting the oem ac delco plugs or ngk one step colder plugs possibly fix the issue? i dont want to go out and buy new plugs if thats not the problem. again no misfire codes... or is this possibly an issue with the tune? i had it tuned back in late january when it was about 30 degrees cooler outside and less humidity

any help would be appreciated

umrdyldo

iTrader: (1)

How are fuel trims?

I would do some logging to see if timing, KR, and fuel trims are good. Also make sure you have no vacuum or boost leaks.

I would say it's in the tune or something was done incorrectly in the rebuild.

JustACobalt

iTrader: (1)

i dont have hpt so i cant log but the meth fitting on my charge pipe is all stripped so i know there has to be a boost leak there. this only happens while in vacuum, cruising. seems to boost fine, i havent taken it over 10 lbs because im still breaking it in. idk this car has been nothing but problems since i got it, used to be my dream car when i had an ls but now i kinda wana sell it...

donkeyballs

iTrader: (3)

I feel you man and i'm ready to sell mine also i have to order some stock plugs cause mine is misfiring all the time and i hope that's the problem also.

Anyone ever try them pulsar plugs?

ronn

iTrader: (3)

Did you have this leak prior to rebuild? Any leak in charge pipes and you lose metered air..that's a problem for sure. You either have a leak or perhaps a fueling problem?

09BlueBaltSS

The "misfire" your feeling is a pretty common occurance on LNFs. Its has something to do with the cam phasers trying to figure out if they wanna be in high load or low load. I had it when I was stock and TF tuned. Now that im BYT tuned its gone. And I think high boost LNFs should be on NGK 3787

gotboost?17

iTrader: (46)

run stock plug, thats what i find best

rukkee

iTrader: (3)

Tighten the plug gap up to .030 or .032 and try it ..... .036 is still kinda wide if your tuned .

JustACobalt

iTrader: (1)

well the spark plugs are bkr7es-11 and they are a wide gap plug set factory to .044 so i think .036 is already pushing it. im going with either tune or boost leak now, ill have to wait to get tuned later to see how the fuel trims look. could it possibly be low compression in one cylinder?

DillySS

I run a .32 with NGK one step colder. If your not pulling codes its gotta be the plugs. LNF being so finiky with gap and plugs I would try stocks or one step and you should be good.

JustACobalt

iTrader: (1)

wouldnt it pull a misfire code if it was the plugs? if i do get plugs im going with the ngk 3787s

rukkee

iTrader: (3)

I used to run bkr7e's in my LSJ .... I think someone messed up when they installed them in your LNF . I would get some stock Acdelco's for your car and gap em tight . From what I've read LNF's don't need one step colder plugs .

donkeyballs

iTrader: (3)

I have have autoliteXP and i have had numerous misfire codes in cylinder 1,2,3,4 so i'm putting stock plugs in and i hope it fixes it. The autolite's worked good on stockish tune but its too much i think with the new turbo.

HHRSSouth

Since you have an upgraded turbo, I would try NGK 3787 and leave them gapped at .032 like they come.

I just checked mine and they look about the right heat range on the BNR 2871 @ 26psi.


Autolites are crap these days, unfortunately.

Its hit or miss with them, I ended up going through 8 new different plugs to find 4 good ones for my turbo van.

JustACobalt

iTrader: (1)

im pretty sure that my problem is coming from the meth fitting on the charge pipe. it used to have an o-ring to prevent leaking but that broke off. plus its stripped so bad that i cant even tighten it with my fingers until it slips off the thread. ill take a picture but its the farthest one on the left in the pic on this website

The Best Water injection system and water methanol injection systems at AlcoholInjectionSystems.com

HHRSSouth

Well are you getting the misfires and stutters when your not spraying meth aka below what you have injection starting at and idle?

I would still try the correct 1 step colder plugs, since your running Meth and a bigger turbo to boot.

JustACobalt

iTrader: (1)

yeah it happens when there is no meth spraying at all. my start psi is set at 8 and this all happens at 15 lbs vacuum. im thinking that since the charge pipe has a leak (stripped meth fitting) that maybe that has to do with the stutters in vacuum

mongorat427

iTrader: (82)

NKG LTR6IX-11 Iridium are one step colder. .32 gap. Works great for me on 93. On E85 Im regular heat plugs

JustACobalt

iTrader: (1)

UPDATE:

all is well.

https://www.cobaltss.net/forums/2-0l...erfect-255448/