Stephen Max

iTrader: (59)

This question is in the context of 4th gen Maximas. I'm seeing evidence of spark blowout at high rpm. Right now I'm running .030" plug gap. I'm getting advice that reducing spark plug gap any more may increase the chance of misfiring because the spark may not be big enough to produce consistent ignition, especially at higher boost levels at high rpm.

Increasing spark voltage would definitely help, but how?

IceY2K1

iTrader: (3)

Honestly, I doubt that's your problem, but *SUPPOSEDLY* the Iridium IX or whatever require LESS voltage to spark which can help under-powered ignition systems.

You guys have coil packs, right?

JeffesonM

iTrader: (5)

I recently saw a thread in the 4th gen forum where someone from overseas asked about a company that supposedly produced performance ignition coils... I'll see if I can find it.

here it is

Jeff92se

iTrader: (82)

Stephan, how can you tell if I can ask. That's an interesting thing to know.

I know HKS had that TwinPower system. One or two guys have used it.

Thing is, it's the coil itself that provides the voltage ramp up. It's simple for a dist ign system as you only have to replace one coil. ie.. msd blaster coil, crane etc... And most coils are common fitment. But when you have to deal with special fitment individ coils like on our maximas, it's going to get difficult. I've always wondered if you can take the coil pack apart and replace them with different innards?

Synki

They, he has individual coil packs. Besides the HKS kit, there isn't much more available.

The OEM system is VERY efficient as is.

Even us Scooby guys run stock coil packs. The stock coil packs have been providing more then plenty of spark for guys running well over the 500awhp mark.

Few guys have ran the HKS kit and gained 1-2hp TOPS.

IceY2K1

iTrader: (3)

I was 95% sure.

Considering Mardi@15-16psi, Hal@13+using a SUPER rich wet nitrous, and then Kev@11+psi and Jane@11psi WITH water injection that is VERY taxing on the electrical system being able to produce spark, I *HIGHLY* doubt that's Stephens' problem.

I think he's on a desparate witch hunt at this point.

Stephen Max

iTrader: (59)

Jeff and Icey, the reason I am wondering about this is due to strange high afr readings I'm getting from my wideband O2 sensor at high rpm. At about 6000 rpm the afr suddenly goes off scale in the lean direction. I've asked the Innovate people about it and they say that misfires due to spark blowout at high rpm can flood the exhaust system with unreacted oxygen, resulting in a lean reading. If multiple misfires happen, the O2 sensor goes into a timeout mode for a few seconds, and the controller registers a false off scale lean afr. I am not sure why that happens, I think it is a controller issue.

In order to make sure I did not have an actual fuel delivery problem, I datalogged fuel pressure and did some more testing. The fuel pressure remained high during the anomoly, which was what I expected since engine power has always felt strong at high rpm with no bucking or surging that would indicate a failing fuel pump or clogged fuel filter.

In an effort to control spark blowout (if that is truly what is happening), I reduced plug gap from .036" to .030". This had no effect at all. When I contacted Klaus at Innovate about this, he maintained that reducing spark plug gap can actually hurt by not providing a large enough spark to produce consistent ignition. He also said that running rich can result in misfiring (I am normally running at 11.5:1, although lately I had tuned to 10.5:1 thinking that would help). When I raised afr back up to 12:1, there was still the same anomolous behavior, but now it occurred at 6300 rpm, which lends some validity to Klaus' theory. I can't run at 12:1, though, because I get detonation on warm days at high rpm when I'm getting over 10 psi.

So, if I am indeed experiencing misfiring at high rpm, then increasing spark gap back to .034-.036" and providing more voltage to the spark plugs will help. Or I need to install water/alcohol injection and raise the afr up to the mid twelves. I need to do that anyway, actually.

I'm mystified why this is suddenly a problem, since I was not getting these high afr readings a couple of weeks ago, and now suddenly I am. Which makes me wonder if it is only the sensor going bad.

At any rate, the engine still feels plenty powerful, misfiring or not. I dusted a ratty looking twin-turbo Z32 last night no problemo.

C MAX

iTrader: (4)

correct. thats what gives us some of are hp the coilpacks. i have the hks
and i can't tell the difference with it on or off. but i guess it helps somewhere but haven't dyno'd it yet.

IceY2K1

iTrader: (3)

Stephen,

Don't you have an EGT gauge? If so, temps should drop from misfiring, right? Also, do you think a wideband on a dyno might help?

I'm stabbing in the dark here, but I'm really skeptical it's misfiring UNLESS something is wrong.

How are you adjusting your AFR, with your S-AFC or Cartech? You don't use the S-AFC normally, correct?

IceY2K1

iTrader: (3)

Stephen,

Don't you have an EGT gauge? If so, temps should drop from misfiring, right? Also, do you think a wideband on a dyno might help?

I'm stabbing in the dark here, but I'm really skeptical it's misfiring UNLESS something is wrong.

How are you adjusting your AFR, with your S-AFC or Cartech? You don't use the S-AFC normally, correct?

1MAX2NV

iTrader: (5)

Split fire in Japan or Asia makes coil packs for the 4th gen. That's the only thing I know of besides the HKS DLI.

MardiGrasMax

iTrader: (14)

What heat range plugs?

Perhaps you need somting to control ignition timing so you can run 12:1?

I run to 7200rpm and am at .030" 1step colder NGK coppers w/JWT ECU tuned and my guesstimate of ~10.5:1 and she runs fine, no noticble ignition problems. I have run .028" on my SC set up with no problems with 2 step colder. 300ZXTT's run stock coil packs to 500whp w/ no problem.

nostrixoxide

I think (MardiGrasMax) is onto something here. I think if your boosted you should have some kind of way to control ignition timing. Being able to control the ignition timing this will help with most detonation problems your occur. For example (low octain fuel, to much boost, excessive heat, pre-ignition etc.)

Another thing that "might" help if you do think your getting high rpm spark blow out is to increase the fuel pressure & reduce the injector pulse width with your AFC. Increasing the fuel pressure will create a finer mist & allow the fuel to evaporate alittle sooner because the fuel drop's will be smaller. Retard the pulse width to keep the A/F mixture close to the same as you normally run 10:1, 10.5:1, 11:1? In my opinion I think this will only help if the blow out is being caused by fuel flooding the combustion chamber.

I am not sure if this will help your situation. I'm just trying to review some of the basics and maybe this can help you get to the bottom of things. I in no way have experience with boost generated from turbo or supercharger systems, I'm just stating some fundamentals here. I hope you can figure out whats happening, good luck?