Hey guys. Please help me out here. I got my car tuned to 470 hp at 20lbs boost. It ran fine on the dyno and a couple runs on the street. However, now its starting to misfire. Mostly 4th and 5th gear. Maybe because 3rd gear revs too fast to notice. I'm running the ngk #3330 plugs (#7) gapped to .025. I just put in some fresh set of plugs and still misfiring. On the dyno, we misfired with the msd set up but then switched back to stock and ran fine. Now im only running stock ignition. could it be that? if so, why didnt it happened sooner? Car is tuned on E85.

Could the outside temp be a factor? Cold night vs hotter day? I notice it does not happen on warmer days, but i've only tried it once. Now it's getting cold here in wisconsin so it's hard to try again. Even when the car is fully warmed up at 200-210 degrees, it still misfires. I'm lost here. See my signature for set up. Please help.

Thanks.

 

Sounds like a tuning issue. Get your self a wideband.
Monitor the a/f ratios during these conditions...

 

i have the AEM air/fuel. I'll have to monitor it. However, running lean or rich...would that cause the engine to misfire. I thought a misfire was ignition related.

 

what's the part number for the 8s? Thanks

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by firstclassjdm &raquo;</TD></TR><TR><TD CLASS="quote">i have the AEM air/fuel. I'll have to monitor it. However, running lean or rich...would that cause the engine to misfire. I thought a misfire was ignition related.</TD></TR></TABLE>

it could cause the motor to "break up" .

you want that air fuel to stay between 11 and 12:1

also try to gap the plugs a little tighter. my gap is .020" on the bkr7e ngk plugs making 415 on a bone stock ignition

 

its either break up or too rich? mine did the same thing, fine 1st-3rd, then at the track 4th was popping, upped the boost and it went away

 

Try gapping your plugs a little tighter first. But it may be a tuning issue..

 

i have the dual stage boost controller from turbo xs. on 10lbs, it's not breaking up so i don't think rich is the issue here. Both stages are running the same fuel map that's tuned for 20lbs. I'll have to try the tighter gap. i thought .025 was too tight already.

 

my msd would cut out when i tuned. i went back to stock and it runs like a champ..

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by firstclassjdm &raquo;</TD></TR><TR><TD CLASS="quote">i have the dual stage boost controller from turbo xs. on 10lbs, it's not breaking up so i don't think rich is the issue here. Both stages are running the same fuel map that's tuned for 20lbs. I'll have to try the tighter gap. i thought .025 was too tight already.</TD></TR></TABLE>

wow so at part throttle, WOT, idle, 4 psi and 20 psi is running in the same column.?? damn those AEM boxes have gotten GOOD.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by firstclassjdm &raquo;</TD></TR><TR><TD CLASS="quote">i have the dual stage boost controller from turbo xs. on 10lbs, it's not breaking up so i don't think rich is the issue here. Both stages are running the same fuel map that's tuned for 20lbs. I'll have to try the tighter gap. i thought .025 was too tight already.</TD></TR></TABLE>

thats not how it works...it could be perfect at 10 psi and fuked on 20 it uses different fuel and timing values for different boost levels. are the plugs black as **** when you pulled them out? probably means they are fouling from fuel

 

the 10lbs is running the same fuel map as the 20lbs. we tuned all the way up to 20lbs and then set the first stage to 10lbs. I hardly ever get on it. The plugs were fine when I pulled them out. We're tuned on a very conservative air/fuel ratio. My air/fuel ratio guage reads between 11 and 12 on WOT at the high boost. Again, keep in mind I don't get on it much. Just a little more lately because I've been trouble shooting the misfire. Even then, very conservative with the WOT.

 

tell me something. Im not very familiar with plugs. Whats the difference between resistor and nonresistor? I have the 3330s. not sure of the exact code on the plugs though. They are 7s and gapped to .025.

 

change your distributor.

its not the plugs...especially if its fine at lower boost


i doubt its the AFR, the AFR has to be pretty far off to cause missfiring like that, the car did just come from the dyno so i would hope its atleast in the right ballpark LOL


you already had a missfire issue which was in the ignition (msd) how was the msd disconnected? was it a temptorary (half ***) removal? most MSD problems i have encountered have been related to ghetto wiring, not the actually msd products themselves.....however i have ran into a few problems with the products themselves.


my votes on wiring or the distributor

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Chris Tune &raquo;</TD></TR><TR><TD CLASS="quote">

wow so at part throttle, WOT, idle, 4 psi and 20 psi is running in the same column.?? damn those AEM boxes have gotten GOOD. </TD></TR></TABLE>


lol

 

havent had time to respond to this in a while, but my car died on the road while going out of town about a month ago. Knew right away it was my distributor. car died suddenly at 70 mps. checked and there was no spark, so i called a buddy to bring up his stock gsr distributor. fixed the problem, but not the mis fire problem. so now i know it's not the distributor either...what the heck is wrong with it???

 

maybe my friend's distributor is bad too...??

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Mr Wonderfull &raquo;</TD></TR><TR><TD CLASS="quote">if using a honduh ecu and non resistor plugs, its the plugs. same thing happened to me. Went to resistor (8s) and it went away completely. im gapped at 020 making a bit oiver 500 on pump 92</TD></TR></TABLE>

not true with s300.. ive had breakup on both non-resistor and resistor plugs..