I am running a tuned EMS w/ a 9k fuel cut rev limit. Occasionally my RPMs will lightly bounce at around 6800 or so, dropping about 3-400RPM like I am hitting a rev limiter, what could cause this? I am running ZFR7F plugs gapped at .035 and an MSD Digital 6+, cap, and coil. Does this sound like my spark is getting blown out? I have a WBO2 in my car and my A/F is fine at around 12ish. Car drives normal, I had a valve adjustment done a few weeks ago after overrevving due to a misshift, could it be slightly bent valves? Leakdown tests came out fine. It doesn't seem to do it in all gears, I've only noticed it in 2nd gear, so I doubt its the MSD cutting spark. Is the stock tach fast enough to be pretty accurate on a boosted LS? I am thinking it may be time for new ss valves, springs, and retainers... to replace my bone stock parts that have been a little beaten down by a 3rd->2nd misshift. I don't notice any excessive valve tapping at idle since the valve adjustment, at normal driving speeds it becomes more pronounced though especially when driving next to a barrier

 

when mine was doing sometihng similar to that it turned out to be plug gap , i had to gap them to .32. mine would do it anytime i went into boost. i could ride out the rpms out of boost and have it be fine .

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by itr206 &raquo;</TD></TR><TR><TD CLASS="quote">when mine was doing sometihng similar to that it turned out to be plug gap , i had to gap them to .32. mine would do it anytime i went into boost. i could ride out the rpms out of boost and have it be fine . </TD></TR></TABLE>

Thanks for the reply, I will try a smaller gap once sparkplugs.com finally gets around to sending out my order. Are you running an MSD or aftermarket ignition?

 

MSD is an aftermarket igntion, and yes im running the Digital 6= , cap, MSD wires, and the blaster ss coil

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by itr206 &raquo;</TD></TR><TR><TD CLASS="quote">MSD is an aftermarket igntion, and yes im running the Digital 6= , cap, MSD wires, and the blaster ss coil </TD></TR></TABLE>

I know MSD is aftermarket ... I was referring to the other options available - Crane, Jacobs, etc.. that output a more powerful spark than stock. It seems that most people running setups like ours are able to get away with a bigger gap than .032, oh well. Hopefully that clears it up Thanks again!

 

yea i thought that becuase of that igntion i would need a larger gap and it worked well for NA and mediocre shots of nitrous , but once i went over 100 hp over my na output the car needed smaller gaps? i dont get it .

 

Everytime I have seen this it has been the plug gap. .035 is already much too big for high boost and the gap will have opened up even more if they have been in for a few week. Try a gap in the mid .020s.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by philo &raquo;</TD></TR><TR><TD CLASS="quote">Everytime I have seen this it has been the plug gap. .035 is already much too big for high boost and the gap will have opened up even more if they have been in for a few week. Try a gap in the mid .020s.</TD></TR></TABLE>

I'm only running 7 PSI so I thought I would be alright according to a lot of posts on here that I dug out of the archives... I'll try a .030 next time once sparkplugs gets my damn order out, been almost a month waiting w/ 2 day shipping grrr. Thanks for the reply

 

why dont you gap the plugs you have now and try it ? you have thos eplugs on back order? why not get thme from an automotive store?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by itr206 &raquo;</TD></TR><TR><TD CLASS="quote">why dont you gap the plugs you have now and try it ? you have thos eplugs on back order? why not get thme from an automotive store?</TD></TR></TABLE>

No local stores sell NGK ZFR7F, BKR7E, BCPRs... I will gap the ones I have now I guess, I just don't want to weaken the electrode by gapping em again, I had a plug break off before so I am pretty cautious when dealing with em now

 

Double check your timing, if its too retarded, it will misfire too.