help please, I dont know whats wrong so I dont know what I need to fix

[sluis05]

So heres the problem. When driving around and I put my foot to the floor, right around 5000 and up the motor seems to mis fire or bog. The strange part is it does do it right away, in the first few minutes of driving it works fine and pulls hard no matter the temperature of the motor. Its a 1990 r32 with a RB25DET swap. I have NGK iridium plugs gapped to 0.8 mm. Ive gone through the intake and cant find any leaks. My speedometer is always at 0 and I have heard that can cause a safety rev limiter but I dont know. The O2 sensor looks new (not sure, just recently bought the car)
If anyone has anything that can help I would really be grateful

[Ghost]

is there a boost controller in it? if so dial it back a bit cause it could be excessive boost causing your wastegate to open too soon... if it doesn't change anything (or if you don't have a BC) i'd probably point to the possibility of your coil packs being fried...

I had similar issues with mine, if you recently bought the car it wouldn't hurt to pull the plugs and check them (if you havent already) and check the pins in the coil packs.

*edit... just read your other thread in regards to your plugs.

So looking over the other thread and this one... if its not boost leak... not excessive boost as your claiming only hitting 5 PSI... id say you need new(er) coil packs sir...

[Skym]

I wouldn't thrash engine until it's warmed up. Cold oil temps (oil is too thick when cold, fails to reach / lube bearings at higher rpm which results in wear of surface on bearings) + thrashing is probably one of the quickest ways to blow an engine up. Also pistons haven't expanded enough inside cylinders, so could get scoring of cylinders from them flopping around, etc. Even racecar engines are warmed up before thrashing.

Stock Skyline ECU pulls ignition timing initially during warmup (up to a set coolant temp) to protect engine. Some car manfacturers (BMW?) use a revlimiter that raises as engine warms up. Some aftermarket ECU's have this revlimiter feature.

There's a safety revlimiter at around 5000rpm and supposedly a revlimiter when speedo signal to ECU is at 0km/h (engages at lower rpm than safety revlimiter, can't remember the exact rpm at this moment in time). But it also could be due to excessive engine noise from pistons flopping around, faulty coilpacks (as mentioned above) which knock board inside ECU picks up via knock sensors on side of engine and makes ECU switch to knock maps (knock ignition map can stop engine from accelerating).

[sluis05]

I understand what you mean about the thrashing, but I still have the same issue even when the car is fully warmed up. And thanks for the help guys :-) now I have somewhere to start

[Bruizer]

First of all, fix your speedo. If you bought it broken, the car probably has 200000000km on it now haha.

The get rid of the iridium plugs, they suck. I use Copper V-power. Worse case, you have a bad coilpack that starts failing at the top end.

[Black BNR32]

just to confirm, you are saying it runs great, with no issues, during the first few minutes of start up. correct?

[sluis05]

Yup even if its already warm then after a few minutes it starts doing it again

[Ghost]

Are you running a BoV or stock re-cirulation valve?

[beacher1B0]

Find yourself R33 engine manual and start doin some probin with a multi meter. Justskylines.c0m has it.

[sluis05]

BoV. Coilpacks fixed the problem, thanks for all the help

[Ghost]

right on i'm glad it turned out for ya man