Misfiring at high rev, what I've done so far.

[dekansnowman]

SERIES 2 RB25DET

Ok, so I have issues with anything above stock boost. I started with the Iridiums at first but that turned out to be too hot of a plug like I've read on here from other people with the same issue. I'll list what I've done:

New Copper plugs in the heat range suggested (colder) gapped to 0.8mmChecked every coil pack for damage (found none)Did a boost leak test up to 20lbs on FMIC (Tight as a drum)Checked vacuum lines (setup to best of my knowledge, BOV works,)Have Walboro 255 with stock FPR (plugs from before were pretty dark and gassy smelling)Searched numerous forums and threads but only read people had issues on part throttle.Checked fuel pressure at idle and it seems right, but I obviously can't check it at WOT because I have no access to a dyno.Here's pics and a video of my car at a small event to give you an idea of sound.

Now, just so you know this was done with colder range copper plugs and before I couldn't boost above 7lbs without hearing this noise and feeling power loss but now I can hit about 10lbs freely and anything above 12 gets the stutter at WOT and around the higher boost I have it set at.



Video: http://www.youtube.com/watch?v=hDbU0cHx53Q

Modified by dekansnowman at 3:33 AM 3/2/2010
Modified by dekansnowman at 4:25 AM 3/2/2010

[Cjmartz2k]

It's your coil packs man. You usually don't SEE any damage on them. They just go back from heat/age and arc through the weakened plastic instead of firing the plug. I've got a set of series II coils if you want, but you could always try taping them up with electrical tape first. That works sometimes.

[dekansnowman]

Not that I'm knocking your input, but wouldn't they mess up all the time? Or the spark is more intense at high load and that exploits whatever is failing?

I'll try taping and anything else to these but is it possible my fuel is too rich? Or are these just not able to handle the work and that's why it's rich? I know RBs are that way period but I know that after I got new plugs it helped alot.

I wish I could test coilpacks before committing to buying because if I knew that was the issue I would just order new splitfire ones. I would hate to have to do this again in a few months.

How good of shape are yours in? And thanks for the response, I really appreciate it.

[Cjmartz2k]

The spark is the same "power" (as far as I know) at any rpm. The thing that makes them miss is when you put more boost/gasoline into the cylinder, it makes it harder for the spark to jump the gap from the electrode to the strap, and it goes somewhere else. Electricity is like water. It takes the path of least resistance. If it's to hard to make a spark in the cylinder, it arcs through the weakest spot, which unfortunately for use RB guys, is usually the side of the coil pack. Do a search on here, it's been discussed 100's of times. It's hard to tell from that vid because of all the tire noise, but I think I just heard 1 cylinder missing, and it usually is only 1 bad coil pack. Easiest was to trouble shoot is just replace half of them and narrow it down from there.

Mine came off a running junkyard skyline that was rear-ended. I knew the person that had them, but never talked to him about them. I just recognized the car in the junkyard yard and swiped the coil packs. $100+ shipping if you want them.

[Sil240]

I would try taping them up like he said before doing anything.It'll cost you $1.00 for a roll of tape.

Or try bringing down the gap in your plugs.You shouldn't have to since your running low boost. But it will tell you that you have a Lack of spark if it works.

I'm no 100% sure, but usually things find the path of LEAST resistance. The higher the cylinder pressures, the harder it is to jump the gap of the spark plug.So if there is a small crack or thinner part of the plastic, it will try to reach ground that route instead of trying to jump that pressurized gap.

I know there's a thread here where I think Darius (not sure) filled up his coil packs with some kind of urethane.

I know I saw a thread about taping coil packs on either SDU or SAU.

If the coil packs are bad you could get those used ones, try the GM buick waste spark setup or the LSX coil setup. 240z did a write up on how to do a LSX on a S2.I made a thread called LS2 Truck coil, but for a RB20.

[dekansnowman]

So I did this today after running errands and soaking up the whole day looking for a Pioneer Touchscreen for the wife.

Are these taped sufficiently?Also, take a look at that one pic where there seems to be corrosion or rust or whatever on the contact section. That evidence of arc?

[Cjmartz2k]

I wrapped the upper portion of mine as well. Another thing to do that I think helps more than taping. Yank the boot off the bottom of each coil pack, twist the spring out in a counter-clockwise motion, the hit that little bucket the spring sits in with a dremel. It gets crud built up on it over time. I made my shiny again just by 1/2 a second each with the dremel and they went from missing to holding 1.8 bar of boost no problem.

Also like I said, if you want some spares, let me know.

[Carl H]

check that your maf adaptor for the filter is not blocking the actual sensor element, it should be true to the bore of the maf.

[dekansnowman]

I'll pull them apart and check what you said, and get my buddy's dremel and clean it up a bit. I'll do all just to make sure. And if this doesn't work, I'll get with you about the coil packs.

And yes, the MAF and adapter are clear with nothing to obstruct airflow. I cleaned the MAF as well and let dry. Haven't started it yet and I cleaned it last night. It was a little dirty, but I don't know if that would be enough to cause issues. Either way, I took the time to address it anyway.

Thanks for the help so far guys, I'll keep you up to date.

[USMCgetsome]

stop messing around with that tape and get this stuff

http://www.plastidip.com/indus...ation or something similar

[flatrate]

i had misfire issues as well, anything above about 12psi it would miss, i gapped plugs, check coils, grounds cleaned s*** etc etc etc... i finally just bought new coil packs, and havent had a problem since on 20+ psi now

I mean the coils are 15 years old...

[dekansnowman]

I'll pull them apart and check what you said, and get my buddy's dremel and clean it up a bit. I'll do all just to make sure. And if this doesn't work, I'll get with you about the coil packs.

And yes, the MAF and adapter are clear with nothing to obstruct airflow. I cleaned the MAF as well and let dry. Haven't started it yet and I cleaned it last night. It was a little dirty, but I don't know if that would be enough to cause issues. Either way, I took the time to address it anyway.

Thanks for the help so far guys, I'll keep you up to date.

[dekansnowman]

stop messing around with that tape and get this stuff

http://www.plastidip.com/indus...ation or something similar

Da Real C'los?

[dekansnowman]

liquid taped all the coil packs and went to start the car to find out that the motor is now acting like the MAF is bad. When the coil packs got bad at that event, I couldn't rev past 4k, since I don't have my tach calibrated for the RB, which is the standard cut for a non functioning maf. The other night before I took everything off it would rev fine, but the only thing I did was spray some maf cleaner on it and let it dry for a few hours even when it only needed a couple minutes. So, FML, I need a new maf I guess before I can even find out if I solved the ignition problem.

[dekansnowman]

liquid taped all the coil packs and went to start the car to find out that the motor is now acting like the MAF is bad. When the coil packs got bad at that event, I couldn't rev past 4k, since I don't have my tach calibrated for the RB, which is the standard cut for a non functioning maf. The other night before I took everything off it would rev fine, but the only thing I did was spray some maf cleaner on it and let it dry for a few hours even when it only needed a couple minutes. So, FML, I need a new maf I guess before I can even find out if I solved the ignition problem.