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High Rpm Miss Fire/flat Sopt

Ezz35

By Ezz35,
in Engines & Forced Induction

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Ezz35 Collaborator

Ezz35

Posted
Posted

since i got my new car last week, i havnt really had a chance to give it a good run till tonight.

I noticed that there is a missfire/flat spot high in the rev range between 5350ish to 6200 rpm then kicks back in at full tilt. this is 2nd and 3rd. its like a surging feeling... power stops, slowly builds revs then bang back with full power. also after this i noticed it miss firing under all load right thru the rev range under load (10 & 12psi)

did a search and found some things about the coils and spark plugs but not sure if it all applies to a S1 rb25.

mods are fmic, full 3", duel stage boost, kn panel, fuel pump and heavy duty clutch.

I have a S-AFC to install yet. would this be able to point out the problem? or maybe a tune via this could fix?

car was supposedly tuned before and made high 190rwkws... my old one made 193 and this feels a lill faster untill this happens

any thoughts guys?

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chrissso Proficient

chrissso

Posted
Posted

Get the safc tuned- should fix it up. Other wise, here's my standard reply...

Are the plugs in properly? - reseat.

Are the plugs the correct heat range? - std is 5. 6 and 7 should also be ok.

Are the plugs gapped to 0.8mm - std plugs are 1.1mm, regapped to 0.8mm makes a sturdier spark.

Are your coil packs old and fcuked? - epoxy old ones or get new ones.

It could be running rich. - ECU adds more fuel than fuel needed running more boost. This can cause misfire. - Need aftermarket ECU or piggy back cumputer and tune.

It could be running lean. -fuel pump not supplying enough fuel to the engine, causing it to ping and the ecu hears this by microphones and cuts/retards the ignition. - need a fuel pump, common in early 33's

GTAAAH Mentor

GTAAAH

Posted
Posted (edited)

Hmm i got exactly the same problem on my rb20, at the same rev ranges. Had an assessment done, was told my pump was fugged and filter fugged, replaced filter and that made it worse, so im pretty sure its pump.. Became more noticeable after FMIC install, which would lead me to believe it was packs. Sucks that theres no easy way to figure out which it is.. When i get a spare 4 or 5 hours ill have to voltage check my coil packs i spose

Edited by r32 gts-turbo
RANDY Veteran

RANDY

Posted
Posted

I replaced my coilpacks with some low-k used ones, problem solved.

See the huge thread on repairing coilpacks to try and resolve this issue, otherwise, replace coilpacks with used or brand new splitfires. =-]

Ezz35 Collaborator

Ezz35

Posted
  • Author
Posted

2min on teh search told me that it could be teh coils, wanted to know if it applied to 33s.

just did the coil diy fix tonight, took it for a spin, had to big missfires and still doin it as before. goin ot have teh safc2 installed and tuned tomorrow, hopefully fix the prob, if not gona grab my old coils from my other 33...

hope this fixes the prob...

Ezz35 Collaborator

Ezz35

Posted
  • Author
Posted
sounds like the stock ECU to me

happens to all of them.

If not, then fuel filter, coil packs, fuel pump... the list gets veeery long :domokun:

arrgh dont say that! lol... my other 33 had a link ecu(useless pos) already installed so i never had to go thru that, will know tomorrow... hope this safc2 is a good as i hear :

mad082 Grand Master

mad082

Posted
Posted
mine was just like, carr drriivveE....hit massive boost, then it just feels like something snaps, power dies, picks up again. over..and over...and over

same here. get onto boost and then it feels like someone has turned the key off, then it comes back, starts lighting the tyres up, dies again.

Ezz35 Collaborator

Ezz35

Posted
  • Author
Posted

problem solved!!! nova performance newcastle did the install and tune today, cars running much better now and faster :)

just noticed under load there is no knock reading but reads upto 2-5 at idle after a squirt... is this normal??

other than that its like driving a new car :yes:

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