Please help! RB25DE NEO Spluttering

[TwoPercentAsian]

Hi Everyone! 

Recently for the past 3 months I've been struggling with a misfire problem with my RB25 (N/A), at first the car was only running on 5 cylinders so I changed the oil and replaced the coil packs with red jackets and they seemed to have remedied the problem until now. Recently I have replaced the coil packs with Splitfires and all spark plugs have been replaced, whenever I drive maybe after 20 mins my car splutters like crazy and there's black smoke coming from my exhaust, and while the car is spluttering if I press the throttle down like 10% the car will just splutter non stop untill I press down more, when I bought the car it was mechanically A+ as I brought it to my mechanic and it ran perfect for the first few months of ownership. any advice on what to look for? or what might be causing these issues?

My R34GT is completely stock other than a cannon exhaust (just the muffler) and the coil packs (Splitfires). Running on Vortex 98.

Thank You! 

- Emmet

[Robocop2310]

Hey mate, it sounds like it could either be an engine problem or exhaust related issue.

You need to have a good mechanic have a proper look at it.

Are you able ro take a video of the problem to provide a better description?

 

[TwoPercentAsian]

Hey Robocop, Yeap I'll take a video and upload it to Youtube tonight for you.

I've taken my R34 to Just Engine Management in Sydney and they actually told me it was the coil packs, so I replaced it with Splitfires but my car still splutters. I installed the Splitfires and fresh sparkplugs last Friday (26/10)

[Ben C34]

I would be trying a different cas to see if that helps. With heat they can get worse. First thing that's easy as is clean the maf, but that's not likely to help in this case.

A video won't help, and I can't see what an exhaust related issue would be, but hey it's up to you.

[Robocop2310]

50 minutes ago, TwoPercentAsian said:

Hey Robocop, Yeap I'll take a video and upload it to Youtube tonight for you.

I've taken my R34 to Just Engine Management in Sydney and they actually told me it was the coil packs, so I replaced it with Splitfires but my car still splutters. I installed the Splitfires and fresh sparkplugs last Friday (26/10)

Hey mate, I ruled out faulty coils and sparkies as you’ve just bought brand new ones.

I mentioned exhaust as holes in the piping or blockage can cause misfire and suttering.

Come to think of it also try cleaning your AFM.

Cheers

[GTSBoy]

It is time to tell the OP that there are a million million threads on here asking the same question.  Some searching will turn up the million possible things that could be causing this, that I am not going to type out again.

[AngryRB]

Time to start replacing every sensor and part of the car, im currently half way there and still have a similar issue.

Current theory is the tank could be full of crap leading to a dirty fuel system.

[TwoPercentAsian]

20 hours ago, AngryRB said:

Time to start replacing every sensor and part of the car, im currently half way there and still have a similar issue.

Current theory is the tank could be full of crap leading to a dirty fuel system.

I never thought about the fuel tank, but interestingly I fuelled up to full and the car was very good for two days, but once it got to  just above half it started to splutter even harder, that might be it, I'll have to check my tank to see if its full of crap soon, but for now I will clean my AFM, if I can't find whats wrong then eventually yeah I will just have to replace all sensors one by one, let me know if you eventually cure the problem even if its not in the near future!