Misfiring problem. Always at 3800-4000 rpm under load ? ( gt28rs SOHC )
 

Well like the title said.... Ive been at my tuner shop last friday to get the new setup tuned and there is always this stupid misfiring issue right when we cross 4000rpm !!

We have to pass this point without loading the engine too much but if we start in 3rd gear at 2000 rpm and go WOT the engine will just start misfiring when when cross this point. My tuner played with the timing, fuel, VTEC point etc... nothing work. Past that point the engine will pul STRONG until the redline without any issue. Its strange since its where the turbo really kicks in....

I run a MSD SCI box with a blaster SS coil... we changed the coil but it didnt help. I suspect the box now...

Do you know if I could run the SS coil without the box to do the test ? If yes how I could do the wiring ?

Or you may have another idea....

Thanks for the help !

someone ??

Re: (yellowturbo)
 

did you check the spark plugs????

Re: (yellowturbo)
 

I am having the same issue with a friend's car, but it won't go past 4000rpm.

adjusting fuel, timing, boost levels etc does nothing. tried multiple crome maps (p30 and p72), premade and from scratch.

tried a brand new dizzy, new wires, new plugs, smaller gap, nothing.

try a smaller gap though, it may be a good step towards resolution.

well they are gapped at 0.28'' so its supposed to be good...

well its only when crossing 4000rpm under load... if im in 3rd at 4500rpm and I floor it there is no problem at all !??

Re: (yellowturbo)
 

all we can really say is check over the ignition system if your sure its not a tuning problem...since i see you have a msd sci system (same one i run) you may want to make sure the msd box itself is grounded...i know if you install the msd system with the rubber spacers according to the directions the box itself is not grounded to the chassis...although internally it may be grounded to the connection it has to the battery...but its still good to ground the box to seperately

Re: (2k.civic.si)
 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 2k.civic.si &raquo;</TD></TR><TR><TD CLASS="quote">all we can really say is check over the ignition system if your sure its not a tuning problem...since i see you have a msd sci system (same one i run) you may want to make sure the msd box itself is grounded...i know if you install the msd system with the rubber spacers according to the directions the box itself is not grounded to the chassis...although internally it may be grounded to the connection it has to the battery...but its still good to ground the box to seperately</TD></TR></TABLE>

yeah I will look at the ground thats a good idea cuz I just moved it last winter !

Re: (yellowturbo)
 

my teg would do that (all motor tho) when the ground that was on the back of my thermostat housing would kinda "hang-loose." Check all of your grounds even the ones for that ridiculous msd box you have in your engine bay https://honda-tech.com/forums/images...s/emsmilep.gif

Re: Misfiring problem. Always at 3800-4000 rpm under load ? (yellowturbo)
 

this is the same exact issue that I may possibly be having. we changed the plugs, and it went away for about a week and then just started happening to me again. but my problem is that we cant get vtec to engage on this p72 with crome, and the plugs get loaded up with fuel because the injectors I have supply the higher cam up to 8000 rpms. anyways, maybe some of the plugs are fouled.

Since ur ignition is upto scratch, how is ur fuel pressure? tegasaurus referred the to the ground which controls the fuel pump!

Re: Misfiring problem. Always at 3800-4000 rpm under load ? (yellowturbo)
 

I would start with getting rid of the msd and seeing if an oem ignition setup will work. Honestly that has alway worked best for me. MSD has given problems in the past on cars I tuned. A recent one would start breaking up as soon as vtec hit no matter where it was set and even at light load. Took out the MSD and added a bunch of grounds to the engine bay and it completely got rid of it.

Re: (Weq)
 

If your positive it's not tuning related, bypass the ignition box. The 2 wires coming from the distributor, that hooks up to the msd box, run those straight to the coil. 1 positive and 1 negative. That should bypass the box altogether. Hope that helps, Paul

Re: (TurboTegB18c)
 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by TurboTegB18c &raquo;</TD></TR><TR><TD CLASS="quote">If your positive it's not tuning related, bypass the ignition box. The 2 wires coming from the distributor, that hooks up to the msd box, run those straight to the coil. 1 positive and 1 negative. That should bypass the box altogether. Hope that helps, Paul</TD></TR></TABLE>

Thats what I will do after looking at my grounds...

UPDATE : when im full throttle starting from 2500-3000 rpm I hit full boost at 3500rpm and I pass this misfiring region without any problem ???? When im in mid boost and mid throttle now the misfire happens http://images.honda-tech.com/set1//smile/emcrook.gif That really bad since the car is perfect past this region.....

Re: (yellowturbo)
 

change the distributor and all your problems will be gone. its exactly what happened to my car before when i uploaded the wrong aems basemap. change the wires too cuz their next.

Re: (turboeg77)
 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by turboeg77 &raquo;</TD></TR><TR><TD CLASS="quote">change the distributor and all your problems will be gone. its exactly what happened to my car before when i uploaded the wrong aems basemap. change the wires too cuz their next.</TD></TR></TABLE>

damn I also runned with a wrong base map that the stupid tech at AEM instaleld in my computer for I dont know why ( I returned them my EMS for a small problem... HOPEFULLY I was doing my broke in period on my new clutch... My tuner is the one who find that it wasnt his map... )

I will change the dizzy for sure now that I read this !

https://honda-tech.com/forums/images/smilies/emthup.gif

I'm not convinced it's not a tuning issue.

Re: (blundar)
 

its not really the tuning that kills the dizzy. its when you havent zeroed in the timing of the EMS to the dizzy that kills it. it has something to do with the stat sync. of the EMS.

Re: (turboeg77)
 

If your car was sitting all winter maybe you have some water in your tank from temp. change. Thats what happend to me. Just an idea.

Kevron

update... its not the MSD SCI box... I removed the box last weekend and it still do the same stupid thing.

Damn I cant understand what could cause the car to misfire always at the same spot.

I did another test... if I floor the throttle at 2500 RPM and let the boost built it wont do anything ?????? Its just when im partial throttle.... I begin to suspect a tuning issue.....

Re: (yellowturbo)
 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by yellowturbo &raquo;</TD></TR><TR><TD CLASS="quote">update... its not the MSD SCI box... I removed the box last weekend and it still do the same stupid thing.

Damn I cant understand what could cause the car to misfire always at the same spot.

I did another test... if I floor the throttle at 2500 RPM and let the boost built it wont do anything ?????? Its just when im partial throttle.... I begin to suspect a tuning issue..... </TD></TR></TABLE>

partial throttle it does it but not under load...its the tuning

my friend had a similiar problem with his microtech, the ignition driver had issues with higher revs. He did the same, MSd box and all, nothing helped until he switched EMS's.

Re: (blundar)
 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by blundar &raquo;</TD></TR><TR><TD CLASS="quote">I'm not convinced it's not a tuning issue.</TD></TR></TABLE> Sounds like a tuning issue, I would say it IS a tuning issue. I have been there.

Re: (turbozxi)
 

sounds dumb, but I had a similar issue at part throttle.

If you're running an HKS sequential BOV, try cranking on the spring or just run without vacuum line to the BOV and see if it fixes anything.

Re: (Synapse)
 

I had the same problem with my MSD SCI box. BUt my engine is N/A, but i replaced all my grounds and the problem went away.

thanks for all you reply. Im pretty sure that its my igniter... I will try a new one soon.