Missfire Boost@4500-5500 RPM - The Answer! (for me at least!)

[SilverECR33]

Oh i forgot to mention. It seems to be doing it Randomly. It did it once last week (after which i took it easy then didnt see the problem again) , Untill this week!. its doing it each night. But each night im driving late and the air is quite cold. It drives perfectly not under load. but once underload then I have issues. When I drove it to work today it went perfectly, snakin 1-2-3rd no probs. and it was smooth all the way thru.

I have monitored AFM voltages, AFM air flow rates, boost and pressures, incase of leaks etc. everything seems fine. no changes have been made to the car since it was tuned over a year go making 350 atw. its got me stumped. I figure maybe one of the plugs has became dodgy so im currently replacing them with older ones i had from last service that were still 80% good. I have checked all the splitfire coilpacks and all still look brand new, no hairline cracks or anything.

No scorching marks found at all. The coilpacks are also cooled in my engine bay due to my custom valley cover I made. So they are not heat soaked.

Last winter, the car had no trouble in winter on full boost.

Edited July 20, 2010 by SilverECR33

[Rolls]

Running too rich will cause a misfire as well people. I had brand new splitfire coil packs, brand new plugs gapped to 0.65 and it still misfired. Got it on the dyno and it was getting down to 9:1 AFRs which are low enough to cause a rich misfire.

A proper remap fixed this issue straight away.

[soundtone]

Just bought an R32 GTS4 that was missfiring like an absolute bitch.

I changed the spark plugs today and put a new fuel filter in. Everything is absolutely sweet as now

There was black fuel coming out of the old fuel filter, it looked more like oil than fuel. So I'd say it was all clogged up with shit. Also the new spark plugs I put in were the NGK's at $5 each and they are gaped at 0.8mm. The cars pretty stock except for an exhaust. Worked for me. No more missfires!

[TriniGT]

Hi I have been getting the occasional TCS and SLIP light coming on on startup. Fix it by switching off and starting again. Last week I got the problem when I was driving though and immediately after that it followed by a CEL which caused the idle to be irratic and do drop to about 500rpm, looked as if the oil pressure was dropping as well as becuase of the irratic idle. Luckily I was around the corner from home and got her back and decided to check the problem online to see if anyone encountered it. Low and behold it is a known problem with coilpacks so I decide to scrp the center cover and have a look at the coilpacks. I am currently running Iridium 7's with a gapping of 1.1mm that I regapped to 0.8mm. I was never confident on the manual gapping and decided to swap out the Iridiums for some NGK coppers with a 1.1mm gap as well. Now I have a huge Oddesey battery so I know the power is not the problem.

I swapped the plugs out and inspected the coilpacks thoroughly same time and they all look like brand new so I put them back in and refitted everything and started her up. After a couple of seconds the TCS and SLIP came on and the CEL a little later as well. On some more reading I heard to first check my timing, this car came from Japan with a Blitz Access ECU and a Pivot ACS-M controller to adjust the Air/Fuel Mixture, I had a wideband attached and made the fuel adjustment for our octane. This is a temporary measure until I can afford a proper standalone setup. Anyway, I followed advice and checked timing, bringing the car to operating temp and then connecting the timing light and unplugging the TPS harness as this is an RB25DET Neo. Checked the timing and it is at 10*, I know it suppose to be 15* so I adjusted the CAS and got it to be at 15* then reconnected the TPS harness and rev the car and checked to see that the timing advances accordingly and then switched the ignition to the OFF position and then restarted clearing all the logs. Now when I start the car there is no TCS or SLIP light and thus far the CEL is not there. I am yet to take the car for a spin to see if it has gone away but I am still getting a slight miss, hoping that it may clearup with a couple of spirited trips but if the lights come back I will be pulling the codes off the consult connector to see what code it is throwing, I should have done this initially but it slipped me. What I also found when I clipped back in the TPS harness is that the timing began to fluctuate and it was difficult to see where the timing was at with the gun, is that normal?

[TriniGT]

I pulled the codes from the CEL as they came up when I started the car tonight. Here is what I got

17 - ABS/TCS Control Unit Circuit. Throttle Control Unit detects malfunction in the system/TCS/ABS Control Unit detects malfunction.

21 - Ignition Signal Circuit. No Consecutive Ignition Signal while the engine is running

43 - Throttle Position Sensor Signal Circuit. TPS output voltage is either higher than 4.7V or lower than 0.06V for predetermined time while parked/neutral position switch is OFF and vehiucle speed is less thank 4Km/hr or higher

Could it be that the coilpacks are causing the other errors to come about? When I started the car the idle was about 2000rpm and then very abruptly it dropped under to about 500rpm and then the idle sounded all weird. Any ideas or should I change the coilpacks and work from there?

[Galois]

I pulled the codes from the CEL as they came up when I started the car tonight. Here is what I got

17 - ABS/TCS Control Unit Circuit. Throttle Control Unit detects malfunction in the system/TCS/ABS Control Unit detects malfunction.

21 - Ignition Signal Circuit. No Consecutive Ignition Signal while the engine is running

43 - Throttle Position Sensor Signal Circuit. TPS output voltage is either higher than 4.7V or lower than 0.06V for predetermined time while parked/neutral position switch is OFF and vehiucle speed is less thank 4Km/hr or higher

Could it be that the coilpacks are causing the other errors to come about? When I started the car the idle was about 2000rpm and then very abruptly it dropped under to about 500rpm and then the idle sounded all weird. Any ideas or should I change the coilpacks and work from there?

i got those same errors once when i forgot to plug in a couple of plugs near the throttle body, very embarrassing haha

[Galois]

a note for anyone in between the misfire phase and the solution phase:

disconnecting the stock boost controller solenoid lowered my boos to the actuator setting (7psi for me) and stopped the misfire, if I'd known that many months ago I'd have saved my engine all that misfire damage (not too bad, wears piston seals apparently, and would only increase the petrol contamination of the motor oil).

Just a thought

[KnightRiderR33]

i have this problem only my problem is visible.. the 2nd coil at the rear of the engine was fugged big time it looked like it was melted leaving about a 1cm gap for spark to fly out.. i got the new coil 2day and ill fit on on saturday hopefully i wont get a miss

[KnightRiderR33]

I have this problem and its so fustrating ive tried taping the coils even thoug i could not see a crack i did it just incase ive checked all my piping and hoses no leak theres only 2 things i need to try now the spark plug gap and the over fueling test which i dont know how to check i do get a slight odur of fuel every now and then so if anyone can help me feel free ta give me advisee PLZZZZZZZZZZZZZZZZZZZZZZ IM DESPRET LOL

[chocco]

I tried the tape mod to no avail so the next best thing (without buyin new coils) I took the coils out while still in their metal frame and filled the outsides with sikaflex to pretty much fill the gap from the coil pack to the metal frame itself. Stopped the miss fire with a set of new plugs and its been goin strong for over 4000kms so far.

[cannabiscorpse]

Hey guys, i have just bought a 95 gtst and am having these problems. Its pretty inconsistant, and it ran noticably better when i replaced a coil that was cracked on the rubber part over the plug, I have tried taping them but wasnt sure whether i need to tape the rubber part that goes over the plug too. Did you guys tape the rubber part?

I have also changed the plugs and regapped them to 0.8 The car only runs cat back zorst, a pod filter and the solenoid mod, but hits around 9psi. I dont think too much boost is the issue at the standard level though.

Edited January 8, 2011 by cannabiscorpse

[suffolkssports]

Hi guys, I too now have a miss, I have tried a few things I'll tell you what I've done and you can hopfully tell me what to try next?

It is a R32 GTR It will only miss when hot (about 85 plus on the power FC) once hot will miss at idle but if left to idle for a few minutes it will cool down enough to go away but as soon as you try to put it on boost (4000rpm to 5500rpm) the missing very clear.

Whist it is missing at idle I have been able to test what cylinder is missing and it is forth pot back from the front of the car every time. I have swaped and changed plugs and coil packs but always the same (pot number 4) and getting a bit worse every day. it makes no diff what boost setting it is on. The plugs all look the same (but are all very lean looking)

The last work I do to the car was replace the clutch in the air con compresser and give it and oil change and new coolant, I don't think I changed anything by that but may have bumped something. started playing next time it got up to temp.

What should I try next?

Also can the miture be turned up a little while I'm waiting to do other work (dumps, turbos) so as its not too lean ( will be dynoed after the extra work is done)

[Rolls]

How is a safc gonna fix faulty coils?

sure, it might mask the problem by changing the fuel ratio so as the spark is easier to make, but the problem will still be there and eventually get worse and catch up to ya! IMO Anyways...

they run so rich that even with good coils it wont spark half the time. I had brand new splitfires, 0.65 gapped plugs and still had a bloody miss, got it retuned so it wasn't running 9-10:1 (maxed out the lambda it was that rich) and it was fixed instantly.

Even the shittiest coils every covered in scorch marks almost never miss with a retune.

edit: for some reason it loaded the first page

Edited January 31, 2011 by Rolls

[suffolkssports]

Hi guys, I too now have a miss, I have tried a few things I'll tell you what I've done and you can hopfully tell me what to try next?

It is a R32 GTR It will only miss when hot (about 85 plus on the power FC) once hot will miss at idle but if left to idle for a few minutes it will cool down enough to go away but as soon as you try to put it on boost (4000rpm to 5500rpm) the missing very clear.

Whist it is missing at idle I have been able to test what cylinder is missing and it is forth pot back from the front of the car every time. I have swaped and changed plugs and coil packs but always the same (pot number 4) and getting a bit worse every day. it makes no diff what boost setting it is on. The plugs all look the same (but are all very lean looking)

The last work I do to the car was replace the clutch in the air con compresser and give it and oil change and new coolant, I don't think I changed anything by that but may have bumped something. started playing next time it got up to temp.

What should I try next?

Also can the miture be turned up a little while I'm waiting to do other work (dumps, turbos) so as its not too lean ( will be dynoed after the extra work is done)

Last night I tested compression all good around 162 and pulled out superspark coil packs put old coils back in the car (they were fine when I pulled them out) still missing on #4 but only when hot. The car has a power FC and last dyno was June 07

Your suggestions would be appreciated.

[suffolkssports]

Hey guys been away and no time to play with car. But I fitted a new superspark igniter yesterday and the car now runs as good are ever. prob solved

[reNEGaDe88]

Have a RB25DET with stock coilpacks. Always had a miss fire on idle even with copper or iridium plugs. Car made 291rwhp on stock turbo.

Then I got a GT3082, car makes a 351rwhp. But it has a horrendous missfire on full load, boost @18psi.

So I took my coilpacks out to silicone/tape them. And saw #6's coilpack and plug were burnt out. Thoughts?

Edited February 22, 2011 by reNEGaDe88

[Galois]

Replacing coilpacks ends up being a must for the long term skyliner, they're probably the cause of your problem. The coilpack loom sometimes needs to be replaced too, they're like $180 from nissan or something (I can't remember, that might be way off). From the picks you might be up for one of these.

Coilpacks have a few options though, depending on who you go with. The nissan coilpacks will be just under $200 each, which is why people use splitfires for half that, or yellow jackets for ~$400 for all.

[FENZ]

Hello guys hoping u can help me out !

bought a R33 gtst about a mounth ago i love it good upgrade from my s13

i drove to work this morning car ran like normal went to work but weather was no good so didnt have to as i am a fisherman

car sat for a hour 1/2 turned it on and ran like a bag of shit missing real badlly anyway had to get home about half way home she

ran like gold again i noticed as soon as engine got to normal temp it ran ok again got home went back to sleep

went to go for drive and same thing again ran no good until engine warmed up so buggered if i know i recentlly put

new vacume lines and aliminium radiator on maybe i have disturbed something but i doubt it ????? anyone have any ideas

[Ben M]

i have the same problem, turns out its due to one of my injectors leaking at the top. it missfires untill it hits full boost then it pulls fine. also at idle i put my hand over the exhaust and little bits of unburnt fuel begin to cover my hand. problem is solved by replacing the o-rings on the top to reseal it. just thought i'd let you know for people who are also suffering from miss fires on boost but the coil packs arent the problem.

[joshw33]

i had the same problem as soon as i hit 4000-5000 rpm it it will missfire even on low boost

i put new plugs in it [bPCR6E 0.8mm] ran ok on low boost but as soon as you put boost in to it it runs like shit

so i tried to silicon the coil pack still no good then i went and bought new coil packs splitfires runs heaps better

no missfire as soon as it comes on boost it starts pulling and then about 4000-5000 rpm it doesn't seems to pull as hard

and then it starts pulling again so im thinking i might need to try a colder plug or smaller gap

any suggestions would be appreciated thanks