RB25DET*MISFIRE*AFTER 19psi

[SillyRB]

Well my car has been on the dyno mulitple times in the last month. Trying to figure out this mis-fire problem i have been having. We turned the dwell up and down for the spark and the misfire continues. There is no misfire @ 19 psi but the second we try to go past 20 psi the mis-fire begins. We tried a variety of plugs, a variety of heat ranges 7 & 8's and different gaps. NO LUCK. Its fine @ 19 psi, and 20 psi there is a misfire. I talked to Mack @ Mckinney he told me to buy a XS Enginnering Power Pack, http://www.xs-engineering.com/...tails i purchased that, and sadly to say it did not help in my case. The problem still occurs. 2 things the power pack does serve as an ignition amplifier but i believe it works on stock ECU'S and was not applicable with the microtech.So now i am wondering, i have spoke to Nate a while ago and he told me to upgrade the coils to something like Bosch or that nature. I am leaning towards upgrading the coils. Any other suggestions.
Modified by SillyRB at 11:18 PM 9/20/2005

[goofynick6]

Well my car has been on the dyno mulitple times in the last month. Trying to figure out this mis-fire problem i have been having. We turned the dwell up and down for the spark and the misfire continues. There is no misfire @ 19 psi but the second we try to go past 20 psi the mis-fire begins. We tried a variety of plugs, a variety of heat ranges 7 & 8's and different gaps. NO LUCK. Its fine @ 19 psi, and 20 psi there is a misfire. I talked to Mack @ Mckinney he told me to buy a XS Enginnering Power Pack, http://www.xs-engineering.com/...tails i purchased that, and sadly to say it did not help in my case. The problem still occurs. 2 things the power pack does serve as an ignition amplifier but i believe it works on stock ECU'S. IF anyone is intrested in purchasing this please let me know (Just an FYI).

How's the a/f? Are you running out of fuel maybe? Sounds like ignition, but could be leaning out.

NickSo now i am wondering, i have spoke to Nate a while ago and he told me to upgrade the coils to something like Bosch or that nature. I am leaning towards upgrading the coils. Any other suggestions.

[SillyRB]

NO its not fuel related. ON the dyno the car is approx ~11.7 all the way through the pull

[rbsileighty]

What mods do you have (hopefully a lot running that high of boost on a RB25)? Have you checked all of your coils? I know you say it's fine before 20psi, but maybe one or more is not as strong as the others... they are not new remember...

I've always heard there is no need to upgrade coils until you have a stupid amount of power (something like 600+)

How are you controlling fuel and what octane are you running? Maybe one or more cyl are getting to much fuel or to little air and can't ignite the mix. Do you know which cyl(s) have the misfire?

[Eikon]

Just a guess... might you be exceeding your MAF sensor limit?

If it is coils, I have seen people get rid of the stock Nissan coil packs and go to three splitfire upgraded coil packs that they mount on the firewall or strut tower. Then they run wires direct to the spark plugs.

It looks sort of funny on an RB, but is def. an upgrade.

[SillyRB]

What mods do you have (hopefully a lot running that high of boost on a RB25)? Have you checked all of your coils? I know you say it's fine before 20psi, but maybe one or more is not as strong as the others... they are not new remember...

I've always heard there is no need to upgrade coils until you have a stupid amount of power (something like 600+)

How are you controlling fuel and what octane are you running? Maybe one or more cyl are getting to much fuel or to little air and can't ignite the mix. Do you know which cyl(s) have the misfire?

Well i do have the supporting mods. But remember when running an EMS such as a microtech or haltech the coils are reading @ a different voltage and dont function in the same way as they do with an OEM computer. Its not a bad coil , because i tried alternate coils from a different RB25. I switched them all out.

[SillyRB]

Just a guess... might you be exceeding your MAF sensor limit?

If it is coils, I have seen people get rid of the stock Nissan coil packs and go to three splitfire upgraded coil packs that they mount on the firewall or strut tower. Then they run wires direct to the spark plugs.

It looks sort of funny on an RB, but is def. an upgrade.

NO MAF, with the LT-12 EMS, MAP 3.5 bar

[Joe]

when i read this the first thing i thought was spark blowout. is there any way you could get an ignition scope on the engine while on the dyno? or some way to look at the firing lines of the spark plugs while its on there? that would help.

[krayton]

Hows your timing up top when it happens. Also is it going really rich when you do 20? or still at 11.7

[SillyRB]

Hows your timing up top when it happens. Also is it going really rich when you do 20? or still at 11.7

Timing up top @ higher RPMS is approx 16-18 degrees.

[gani]

since you are running microtech you should use their coils or bosch like coils. seen the same problem before with an sr.

[krayton]

Timing up top @ higher RPMS is approx 16-18 degrees.

rats. shoots down mine. i had the same problem, but i was slightly retartding mine.

fuels ok up there though? your not drowning it right?

[rbsileighty]

Well i do have the supporting mods. But remember when running an EMS such as a microtech or haltech the coils are reading @ a different voltage and dont function in the same way as they do with an OEM computer. Its not a bad coil , because i tried alternate coils from a different RB25. I switched them all out.

Didn't know you had a EMS... which cyl(s) is misfiring? Same one(s) when you switch the coils?

[eh?]

The Supra guys are using LS1 coils and supposedly they are better than the MSD boxes. IF you have a S2 RB25, they'd be a good match.Did you mess with the coil dwell settings?

[Imissmyturbo]

scoping those coils isn't easy since they go right over the plug. You could run a lead from the coil to the plug and put the scope hookup on there. It would be interesting to see how it looks.

What #'s are you making @ 19 psi?

[SillyRB]

fuels ok up there though? your not drowning it right?

Yes no drowning up there.

The Supra guys are using LS1 coils and supposedly they are better than the MSD boxes. IF you have a S2 RB25, they'd be a good match.Did you mess with the coil dwell settings?

Yes we did mess with the dwell. We went high and and low. As high as 3.25 and the misfire continued. With the VTC not activating the car is making on a MD around low 400's i dont remember the exact # as we weren't really on the dyno for the #'s, more so for problem solving. Thank God for friends who own shops hahaha.

I looked for info but could not find much please tell me more about the LS1 coils with the RB. Yes, i have a S2 motor

Thanks~

[GTR Shop]

Are you running the Microtech in Std or Matrix mode?

[rn240sx]

SO whats the deal...??

Is there nobody pushing over 20 psi on these RB motors...??

[Joe]

people run 20+ psi all the time.

[WeldingHank]

whats your plug gap?

[SillyRB]

Are you running the Microtech in Std or Matrix mode?

I believe its in Standard mode

whats your plug gap?

It was gapped .020-.022Im gonna try gapping them @ .012 - .014 as Nate told me to try that out.