Please help missfire!! And cut outs

[Brady.b]

Hi first time posting on here after many hours of reading trying to sort my r33

Okay its a r33 rb25 series 2 and it randomly starts misfiring really bad, it will splutter, or if on full throtle it will completely hit a flat spot again and again and it even cuts out at times. Plugs are fine replaced the cheap ebay coilpacks to stock ones and even replaced the cas, was thinking harness but when running you can pull on it and it wont missfire. Thing is it does it randomly like on a few odd ocasions it will run absolutely mint no problems at all then it will run so shit like some days it will cut out over and over again...want to get to thw bottom of this, any help is really apreciated 

[KiwiRS4T]

Fuel filter...fuel pump? Blockage in tank?

[hey_aleks]

Need to be more specific..
What mods and how much psi?
Auto or manual?
Is it smoking?
Is it cutting out when you floor it around a corner or when low on fuel?

[Brady.b]

Okay its an auto, nothing major on mods just the usual aftermarket intercooler, pod filter, boost t and exhaust runing about 11 psi. Okay so when  it does it on idle it blows black smoke cause not burning all the fuel and can cut out whenever, for example other day i pulled out my drive way and it cut out twice doing like 15..... fuel filter has been changed and dosent matter if tank is full or not, thanks for the response  guys

[hey_aleks]

Hmm sounds like a fuel issue, maybe put anothe quarter tank of 98 and see how she runs? One of my 33s would start to cut out at around 1/4 tank then not start once it had reached just under a quarter before the low fuel light even went on (probably the owner messing with the fuel gauge needle when changing the cluster bulbs or your fuel filter needs replacing/fuel pump is on the way).
Or it could be a vacuum leak since mine blows black smoke and cuts out really bad when one of my intercooler pipes blow. Are you running the stock blow off valve plumbed back? May have issues idling/starting without the stock bov setup if running stock ecu.
Also if its mainly happening on wide open throttle, lower your boost to 8 to test if the ecu is going into 'rich and retarded' mode.
Also what spark plugs are you running? At 11psi they should be gapped to around 0.8mm (alot of people recommend NGK BCPR6ES plugs).
Also look at your coilpacks if they are factory/ebay ones. I had a splutter on 75%+ throttle running 9psi and wrapping my coilpacks with silicone tape fixed it.

[hey_aleks]

Just read your response, could possibly fuel pump? It sounds like something small to be honest so maybe take it to a known mechanic/a jdm shop/tuner and have them look at it before you spend any more money. If they quote you a ridiculous price, at least you'll know what your issue is.

Just last week my auto 33 turbo was having the same issues without the smoking. I got brand new NGK spark plugs as mentioned above, i taped up all the coilpacks with electrical tape (3 were red Ebay ones and 3 were stock ones, all looked fine to the eye but probably had hairline cracks). The boost was 10, i completely removed the boost tee and ran straight to the actuator to elimate issues with it (some are fakes and some just work shit, just run stock boost until you sort the issue).

[hey_aleks]

Also could be a leaky injector.

[Brady.b]

I thought it could be boost and putting ecu into rich an retard mode but can happen when not on boost at all, dosent matter if tank is full or quater and is not dependent on throtle can happen at all throtle positions, has stock bov and have replaced a full set of coils to stock ones and the car they came of had no missfires or anything..the reason i dont think its fuel is because it just does it randomly like other times it goes hard

[KiwiRS4T]

Sounds like fuel to me. Have a look for free (well its a bit of work). Maybe the pickup has moved...pump is on way out...

[tridentt150v]

Check the plug to your ECU, I had a similar thing and it was the plug.  They only have a single centre bolt and can sometimes twist off on one end.

But personally I'm with Kiwi, take it to a garage and ask them to check the fuel pressure while you're at it.  Its a 5 minute job.