idles fine, drives good pulls hard and then?

[Godzilla32]

hey guys, i was out bombing around in the gtr the other day as usual. on my way back home i notice the car shudder under throttle, right before where the boost gauge levels off at 0. i just drove it home, took the coils off and checked the plugs. they seemed a little loose so i gave them a good nip. i also cleaned the mafs and retightened all the boost piping. it was fine for a bit and then when i really got on the throttle it would pick up then shudder then pick up again. like intermittent power surging. during this time the turbos would shuffle, one time i came onto it and i was just starting to build boost then the blowoffs went and it started to shudder again. coils are good, plugs are nearly new and not sooted up.

[h4X6]

bad O2 sensor maybe?

stock or anything aftermarket?

could be pulling and going into knock map...

[Godzilla32]

very stock, even still has boost restrictor in place. puzzled.. i just took it for a rip and it didnt do it at all. its not all the time. coil harness is pretty crispy so im going to replace that for starters. mines ecu i should mention

[Godzilla32]

yeah now that i think of it, on my way back with the car i was running super fat pig rich and i mean rich to blowing black soot smoke out the exhaust, guessing this is gumming up my o2 sensors. they are going to be replaced. i notice i still backfire a lot and i know that im still running a little rich.

[h4X6]

could be a MAF as well...

see if there is anyone around you that has confirmed working 100% MAFs and swap them in for a day or so and see if the issue is resolved... if not then thats your issue... cleaning the MAFs works most of the time, but only if the electronics are all fine inside... those can go sometimes...

[Godzilla32]

I resolder end the mafs already and a new pair are on the way due to the mesh missing in mine, we'll see soon enough!

[Godzilla32]

I bought some lightly used genuine nissan o2, figuring anything is better then the crap ones I got in there which I'm betting on are caked to the tits with carbon.

[Skym]

yeah now that i think of it, on my way back with the car i was running super fat pig rich and i mean rich to blowing black soot smoke out the exhaust, guessing this is gumming up my o2 sensors. they are going to be replaced. i notice i still backfire a lot and i know that im still running a little rich.

When o2 sensor fails it makes ECU make engine run rich longer (o2 sensor is slower to react). You can test o2 sensors by seeing how fast they switch between the lean, rich and rich, lean voltage triggers (buy a manual that shows how to). If too slow with switching, you replace the o2 sensors. The o2 sensors should be checked and replaced every 40-60,000km.

Can buy a manual here -

http://www.jpnz.co.nz/afawcs0131170/CATID=24/SUBID=273/page=1/products.html