ShayneJ

Yes, it only starts to miss when up high. It wont do it at 3k... And when it starts to miss, even dropping the revs back to around idle it will still miss and complain for a bit and then come good... Did the dry compression test, and got results i have in the first post. Will haver to give a wet test in the next few days... And no, did not get the head tested or serviced.

I am actually running less boost than with the other motor, and had no issues there. And if it were injectors, wouldn't they spring back to life as soon as you drop below the max cycle, not 15~ seconds after the car is at idle/minimal load?

Can you elabortae a bit more? Im not a mechanic and don't exaclt understand what that is... And what is needed to be replaced to fix it and is it exepensive?

GTR fuel pump splitfire coil packs RB20DET computer remapped to run the 25 KKR480 turbo running at 13 psi, making about 320hp at the wheels. Everything else is standard i think. Was purchased with all mods done. Thing is it never had a problem until the first motor went due to bearings and we put the 2nd hand motor in. Thats when the problems started to arise. Run sweet as before it spun the bearings... Now its just been a nightmare

I know this is the best bet, but the closest one is 500kms away. So not exactly practical.

I can only seem to get the problem to happen when its under load. And 5-15 seconds isn't enough time for me to pull over, pop the bonnet and start pulling coil pack plugs off, LOL.... I was thinking its a problem with a valve aswell, but didn't want to bias the answers of people on here. Is there an easy way to test without pulling the motor apart? Anyone else have some input?

Heres the story: My first motor went pop so I bought a replacement from a friend. Put the motor in, and this motor had a weird issue of occasioanlly running on 5 cyliders when you near redline. Then after 5-15~ seconds it will come good again and run like a dream... 2 weeks after this motor was put it, it also went pop and put a hole in piston 1 but i believe it to be because the boost controller failed and ran a fair bit of boost. Now, instead of buying another new motor because it was starting to get expensive. I bought a new complete bottom end from somebody on this forum. We mated the head from the motor that just went bang up together with new gaskets. The thing is this new motor is doing the same thing. It will occassionally run on 5cyliders when you rev it to redline. and again, after 5-15~ seconds it will come good again. We had done a compression test on the motor and got these results: 120 - 125 - 130 - 135 - 140 - 140 I am running splitfire coil packs, which inspected a few days ago and they don't have any cracks. I have been told it could be something to do with the injectors, but then why would it still run rough once the revs had dropped and come good again not depending on the revs? I haven't driven to car much at all over the last 4 months, scared that it will break again.... Before you tell me to put it on a dyno, the closest one is 500kms away so its not exactly practical... Thanks

Yeah, 3rd motor. And no not having luck... Its a weird problem. It comes good after 15 seconds or so after the spirited run. It spits a bit up in the high revs. So unable to test the coilpacks like you said as its running like a kitten by the time you stop. I noticed the problem after we stopped drifting around a round about, on private property ofcourse. Its weird *shrugs*

Ok, I have noticed this a few times. When giving my S2 R33 a bit of a 'spirited' run, it feels like it runs on 5 cylinders. Even after i've stopped giving it a little bit it still seems to be running on 5cylinders even at low revs for a few seconds (1-15 seconds). It has split fire coilpacks, GTR fuel pump. It never happened with my old motor. I did notice it on the second motor, but it only lasted 2 weeks before a hole was melted in piston #1. The third motor (thats in it now) is doing well except for this issue. Any advice on this would be appreciated. Thanks

Yeah could be keen on bottom end, we'll see how f**ked mine is when we tear it apart.

your synchros may be starting to wear and you just try and change gears to quick for them. My gearbox had a grind into 4th no matter how slow or fast you were going. Its quite common that 4th gear synchro grinds in an r33 box as they wear the fastest.

nothings invincible. I have been through 4 gearboxes in my old R31 skyline. though they aint built like the rb25det gearbox. Just don't flat change and always try and wait for the synchro's to mesh and you shouldn't have a problem at all. In terms of strength they are pretty strong but its the synchros which wear out and start to grind. After they were out enough the wear moves to the actual gears (this would be metal deposits left on magnetic gearbox drain plug)

start to notice grinding noise when changing gears and eventually BANG.... The gearbox goes on holidays and wont come back until you rebuild or buy a new one. Just be gentle with the gearbox don't slam it into gear all the time. Change slowly and it will last alot longer

I have heard about a VG30 turbo box has the same internals as the rb25det gearbox. May have to change the bellhousing to suit the rb motor and i think the shifter sits further back (does sit in the standard spot anyway). Pretty sure they are the same length also, so may even be able to keep standard tail shaft. Another option to think about as they can be nabbed quite alot cheaper than a rb25det gearbox.

now leaning towards clutch related issue: Car rolling, in neutral with clutch pedal in and give it a little rev - Vibration happens Car rolling, in 1st, 2nd and 3rd with clutch pedal in and give it a little rev - Vibration (Only tested first, second, and third gears) Car rolling, in neutral with clutch pedal out and give it a little rev - No vibrations! Also; Starter motor died today (thinks) and had to push start the car. Rubbing noise coming through clutch pedal and is audiable. This was went the clutch pedal is pressed in. Released pedal and noise went away while car was rolling from being pushed. soslo_31; I know you told me last night when you bled the clutch Anyone have any other ideas?