R33 Gtst- Flat Spots

[cannabiscorpse]

Hey guys- I have recently bought a standard 95 gtst and have been having problems with it having flat spots. I have replaced the plugs and gapped them at 0.8, replaced the coils with splitfires, and changed the fuel filter.

The car is stock with only minor mods exhaust, pod, r34 smic and a turbotech boost controller set at 9 (As low as i could..) The problem was definately worse on the old coils and plugs, and its not popping and spluttering anymore but it still has flat spots under hard acceleration. I have noticed that if i back off slightly as it starts to miss, and continue to feed power in it drives really well.. (Eg driving at 3/4 throttle the car accelerates fine)

I realise these are newbie questions but any help is appreciated.

Cheers

[scotty_1989]

hey mate,

i had a few flat spots for a while too. Basically i rekon your timing is abit out. Take to a tuner and get them to run it on the dyno. If the curve dips down then back up then down, or something to that extent i would most definately say its your timing. The tuner should be able to fix it for you.

cheers

[mad082]

the stock ecu often has a slight flat spot at around 4500rpm (most noticable in 3rd gear). this is when the VCT turns off and without an aftermarket ecu is pretty much impossible to get rid of.

[cannabiscorpse]

Thanks guys- will definately check the timing out. There is more than one flat spot, and i think im using too much fuel aswell.

[cannabiscorpse]

Just taking it for a drive and feeding it on in third, i noticed that the flat spots are spot on 3500-4000 then again at 4500-5000. The rest of the rev range is pulling really hard. I dont know if i mentioned i am using plugs that are pfr511g. I have gapped them to 0.8 but i have noticed that the other guys on here seem to go with the bcpr6es plugs, so i figure thats my next point of call, hopefully not the ecu!!

[cannabiscorpse]

I have spoken to a tuner (toshi in sydney) and he said that it would be the computer detecting somesort of overboost and that when he remaps the ecu it will be solved. Its a bit of a bummer cause i cant afford the tune for a while. I also tried taking off the boost controller and running the stock t piece, but it still makes around 10-11 pound of boost anyway, and the problem is still there. I think toshi is definately my next priority.

[89CAL]

It would be more so airflow in excess of expected and the ecu will be most likely chucking fuel and taking timid out of it. And as said when it hits the point where VCT switches off it's dying

R33's dont have boost sensing to the ecu so it will be your AFM saying WTF

If he's doing a remap it should fix your problem but you should probably go to the spark plugs you mentioned above as well

[cannabiscorpse]

Did the plugs today, the flat spots are still there- next stop ecu.

[BOOZTJUNKEY]

In my r32 I was running copper plugs bkr6e then went bcpr6es and had flat spots all thru the rev range I doing think changing your ecu will do anything get it to tuner check timing and afr thats the easyiest and less cost effective way to sort the issue out don't take this negatively but I'm speaking from experience

[LANDSCRIBBLE]

from what your describing ive had a similiar problem, same thing happened when the boost was set to 10psi, going up through 2nd or 3rd, then in the higher rev range would noticeably *stall* in power. apparently was to do with the stock ecu freaking out and dumping fuel at that moment, or rich and retard they call it

anyway i upgraded the ecu in the end and got it dyno tuned. smooth as silk now.