testing coil packs

[rb25det250sx]

how do you do it? do i have to take the coil packs out or can i leave them in? does the car have to be running or not? thanks

[Cjmartz2k]

Does it miss right now? If so and you want to find out which one it is, take off the center cover and unplug them one at a time and see if it effects the idle. The one that doesn't change anything is the miss firing cylinder. Trouble shoot from there.

[rb25det250sx]

runs fine at idle, and when i free rev it. inly misses on a load above 9psi.

[rb25det250sx]

um..bump

[Cjmartz2k]

search for coil pack fix on here and skylinesaustralia.com

[rb25det250sx]

okay..so i was meesing around with them tonight. and i unpluged each coil one by one and they all changed the idle...started to run rough.. plugged them bac k in and took it out for a drive thinking that somehow they amazingly got fixed. and still breaks up once i hit full boost.

around 13psi. then when teh boost drops to 9 it still kinda misses.so i turned the boost down to 7psi and no miss. but it feels so doggy after 5 months of running on 13lbs.

so, i tested them and there all reading about the right voltage. cant member what it was but i got it wrote down somewhere.. looking.

and for those of you that didnt know. i got my car running again. . . same block new pistons and rods. acl bearings a coller from Frsport, and got my crank shaft rebalanced and polished at a local machine shop. thanks for the support. hopefully i can do something with my coil packs.

[streeteg]

I am having that same issue above 5500 @ about 10lbs of boost. Just ordered the yellow jacket coil packs from Performance-wise.com. I will keep you posted on the change.

Also will be headed back to the dyno after the packs to get tuned via power FC.

-E

[Cjmartz2k]

If you don't have spares to change out and test, go out, drive it and make it miss a bunch as close to home or where ever you are going to work on it as you can get. Pull the plugs and look at them. The one that's black is your winner. Change the plug, and if that doesn't help. It's the coil pack.

[DrifterProdigy85]

FSM says to test the coilpacks resistance. Im having the same problem with missing over 5krpm under heavy load. Ive done new coilpacks, tps, plugs, and no boost leaks. I love how my RB drives but i gotta say i never had problems like this with my SR and that was over 2x the power.

[Cjmartz2k]

DP, what gap are you running on the plugs?

I've posted this before, but I don't feel like searching for it. s***, I might have to do a write up just so I don't have to type this anymore........

With ignition, electricity acts like running water. It's going to take the path of least resistance. It's going to go somehwere, and the weakest link in even the best, new ignition on an RB is the coil packs. If you coil packs are cracked and the insulation isn't working well, it'll arc there with brand new plugs and small gaps. If your plugs are bad, it'll arc through the coil pack even if the packs are new. If your gap is to big, it'll arc through the pack. If your tune is off, it'll arc though the coil pack. It's all about the weakest link. You might not miss at idle or at low boost, but when you get into higher boost, it'll miss. It's because the mixture in the cylinder is tougher to light off, and you have a weak link.

Other things can go wrong like wiring or a bad ignitor, but those typically cause a hard miss even at idle, just like a completly fouled plug or completly tanked coil.

Keep in mind, one thing can "band aid" another. If you have a "weak" coil pack (insulation isn't the best, but it still puts up a fight to the electricity), and you put brand new plugs in or lower the gap, it might make the miss go away, but you still have a weak coil. Turn up the boost even more, and it'll miss again. Same thing if you have a dirty plug and you put a new coil pack on there. It's all about the weakest link.

One other thing on stock coils vs. splitfires/yellow jacket/aftermarket coils. The only reason they work "better" is because people are replacing old, missing or weak coils with brand new ones. They are the same thing. I have a pile of about 30 coil packs out of everything from a n/a RB20 to a turbo 25 to a RB26. I used to grab random ones out of the bucket when one would go back and throw them on. They are all the same. I run 1.8 bar at over 600hp on stock coils. If you are missing on a stock turbo at 13psi, you don't NEED splitfires, you just need not broken coils. Spend the money if you want, but you're waisting it.

[DrifterProdigy85]

Yup i follow you. Nissan stock ignition systems are pretty good. I made over 500hp on my SR with stock ignition. Anyways my RB plugs are gapped at .030" and i have new SS Performance Coilpacks from RawBrokerage. All grounds are good. Alternator is good. Replaced the TPS and the car drove smoother but still had the miss. One thing ive noticed is the TPS voltage fluctuates alot. With the car off, using my AVCR, it shows 97% at WOT and as i hold the gas open the % slowly increases on its own up to 100%. The voltage stays the same at WOT though. I dont understand it at all. And then when the car is running and the fans kick on, the TPS voltage drops almost .15 volts and has wont read 100% WOT. Ive had 2 RBs, one in a S13 and now S14 and both have had similar issues.

[rb25det250sx]

yeah mine wasn't missing untill recently. i epoxyed my packs like darius told me to do, cuz once we got my car fixed it was missing bad. then epoxy coated them. no more miss, untill recently at first thought it was just the plugs since they havent been changed. . . well i gapped them way wrong then a though wasnt even reading the feeler plug right. so i pulled those things got new ones regapped them RIGHT, thinking it was going to fix my problem, hell no..

funny thing about it is it dont miss over 8psi unless my car has been running awhile and has properly warmed up.

oh and BTW Cjmartz2k there is NO WAY IN hell im going to drive my car around let it get nice and TOASTY sputter like a sunofab**** and then take the plugs out right away. F that. i would burn some s**t!!!

[DrifterProdigy85]

Im talking with some guys on Skylinesaustralia forum and there steering me toward maybe a bad ignitor or maf.

[Cjmartz2k]

RB25det250sx, I didn't mean do it while they were hot. I just meant step on it and make them miss a bunch, then shut the car off. That should leave some nice black carbon deposits on the plugs that weren't sparking. If the miss under load, but then you drive it around for a while NOT under boost and it doesn't miss, you'll kinda clean the plugs off and it'll make reading them harder. Ideally, what I'm saying is go out in the middle of no where, beat on it and make them miss all the way from 1st to 4th, and shut the car down right at redline in 4th, turn the car off, coast and pull over, let it cool down, and check the plugs for which one is black or even wet. I know that's not possible, I'm just trying to get you understanding what I meant.

DP--do you have a wideband? If your MAF is bad, you'll see some crazy a/f ratios even before it starts missing. Do you have a spare MAF to test? Also, try letting it idle, and unplug the MAF and see if it even makes a difference.

[DrifterProdigy85]

I still need to put the wideband from the sr in. It runs a little on the rich side from what I can smell. After it's warmed up the car is hard to start and have to apply throttle to get it to start sometimes. I just cleaned the maf but I still have to drive it. I'm at work so I can let you know if the cleaning helped.

[rb25det250sx]

OH...ok

[DrifterProdigy85]

I cleaned the MAF and it helped a little. Pulls straight through on 7psi. Still has dead spots at WOT with 10psi and 13psi. I ordered an ignitor to try and see if that helps. I feel im very close to solving it though. With everything i try, the car keeps running better and better. Just to be sure, im gonna boost leak the car tomorrow morning. I noticed today that at higher boost levels the spool noise becomes super loud making me think its leaking air and causing the turbo to overspool itself to keep up.

[DrifterProdigy85]

Found and fixed 2 small boost leaks. Drives amazing at part throttle but still has a big loss in power at WOT. Next I'm gonna try another ignitor.

[rb25det250sx]

mine does the same... except the internal gate leaks at anything over 8psi. but when i first start my car up it runs like a champ... but once it starts to heat up and the packs get hot it misses like a sunofab****.

[Darius]

Buy one of my spare ignitors

[DrifterProdigy85]

How much for one?