Boost Spike?

[NisGTR]

having a problem with my car lately, it doesn't happen all the time its just happened to me twice. I think it might be boost spiking. When I'm on 4th gear boost kicks in at 4.500rpm it starts pulling and then all of the sudden its like the car downshifts and over revs. I'm starting to freakout, I'm leading it to boost spike but I need to be sure, I need your opinions to what it might be? like I've said just started to happen recently, mainly in cold nights. I've had all the mods done around a year ago and was working fine. I told my tuner if I needed boost controller and he goes its fine as long as its set to 16psi

[mad082]

do you have a boost gauge? that will tell you whether you are getting a boost spike or not. if the boost pressure increases then you have a boost spike. if it stays the same there is no boost spike.

when you say it's like it downshifts and over revs, do you mean it sounds like it's hitting a rev limiter? so in other words, the car is misfiring? if yes, then it is most likely your coils are on the way out, or possibly the spark plugs.

[NisGTR]

running stock boost gauge on gtr. it doesn't hit the rev limiter at all. its like a smooth transition and then bang all this power from no where and then i let off the throttle. Weird as

[White GTS-T]

Clutch slip?

[NisGTR]

I don't know I've changed the clutch 2 years ago, but it sounds like the same problems before I got the new clutch put in, surely the clutch that's gone. I don't drive the thing hard. But damn its like I hit power and then the car goes to neutral and revs like crazy. only happens on 4th gear.

[White GTS-T]

That's the clutch slipping.

[Grey]

yeh sounds like the clutch is slipping, twin plate clutch time?

[DVS JEZ]

Agreed with clutch slip. Check that there is free play on the clutch pedal.

Check the rear main crank seal hasnt leaked oil onto the clutch