R34 Gt-v N/a - No Power Under Full Throttle

[Deza3000]

Hey guys,

I recently was involved in an accident which has taken my evo out of commission, so im back onto driving the skyline and noticed that the car seems to struggle under full throttle. Its very strange, basically if i give 20-50% throttle, it goes harder than if i gave it 80-100% throttle. Off the line, it revs hard till about 4~4.5rpm but then kinda hesistates and struggles to push through the rest of the rpm. My old n/a r33 was much quicker than this r34 is. It takes me 10+ seconds to hit 100ks per hour under full throttle where as my r33 only took about 7.5.

So far I have tried changing the coil packs with genuine nissan coilpacks (though im not too sure on their creditbillity as i bought them off ebay), changed the air filter, sprayed maf sensor cleaner on the air flow meter, tried 98 octane fuel and its still running like garbage.

Im thinking spark plugs now but not too sure? I checked them when i put the new coilpacks in and they were still in pretty good nic. Also thinking maybe clogged exhaust and or fuel filter? But i dont want to spend too much money on the car only to find its a hit and miss.

Also just a side note: Wasnt too sure if this could be related but i also hear a kind of thumping noise when i accelerate, so i put the car in neutral and revved it but i cant repeat it, only happens when under load.

The car is 100% stock, no mods what so ever. Recently serviced all fluids including rads, drivetrain, motor etc..

Any help would be much appreciated!

Thanks in advance

[Hadouken]

How old is the fuel in the tank?

[Deza3000]

The fuel is fresh as my sister has been driving the car for the past year. She has also complained about the drop in performance under heavy acceleration. Car has done 100,000ks

[Jordy32]

I had a similar issue in my old R32 when it was na, I replaced the fuel pump as it was dying and would struggle at full throttle, good time to do a fuel filter too.

I would also suggest checking the TPS calibration as it may have failed or be giving incorrect readings.

[AngryRB]

sounds alot like an exhaust blockage, could be the catalytic converter, i read an older thread where the traction control made the car sluggish also if that is relevent..

[Deza3000]

Ill have a look at the pump, i have a spare lying around..i think..

My sister wanted an exhaust anyway so i guess it gives her an excuse to buy one I wasnt going to bother cause n/a but if it helps in this situation then why not.

[Deza3000]

Just an update, i replaced the fuel filter and the car was running a little better but not up to standard. I did a test at WOT and got a check engine light. Looks like the coilpacks and sparkplugs are burnt and need replacing unfortunately.

Will report back here once i throw in some splitfires and pfr5g11 plugs to see if it will cure the problem. It sounds more and more likely that the coilpacks are to blame.

[Deza3000]

Okay so the car randomly died twice today. Once when slowing down and once when accelerating. The car starts up fine straight away so i ruled out fuel pump, i suspect coilpacks and sparkplugs, what do you guys reckon?

[ErOR]

Okay so the car randomly died twice today. Once when slowing down and once when accelerating. The car starts up fine straight away so i ruled out fuel pump, i suspect coilpacks and sparkplugs, what do you guys reckon?

Any weird symptoms like rough idle, random backfires, revs down rough?

Checked timing? CAS? Knock sensor?

How does it hesitate and struggle as it revs? Starts cutting out and being jerky or just loss of power as it revs as if its out of guts?

[Deza3000]

Any weird symptoms like rough idle, random backfires, revs down rough?

Checked timing? CAS? Knock sensor?

How does it hesitate and struggle as it revs? Starts cutting out and being jerky or just loss of power as it revs as if its out of guts?

Thats the weird thing, there is no rough idle, starts 100% fine, no back fires (might be masked due to stock exhaust) and doesnt rev down rough.

I havent checked the timing, CAS or knock yet.

It does jerk or anything, when it hits about 3~5k revs it just hangs and revs up extremly slow. Very bad struggle and it doesnt shift even in tip-tronic until 2-3 seconds after its suppose too.

When the car stalls however, the car jerks a fair bit prior to stalling, its done it twice, but i couldnt get it to stall again, so somethings a bit weird

[KiwiRS4T]

You can't rule out the fuel pump. It doesn't take much petrol to fire the engine up - takes a lot more to move 1600kg.

[GTSBoy]

Weak pump

[Deza3000]

Hmm yea ill keep an eye on the pump as well. I couldnt get the car to stall or die again, it was just that one day Anyways ill change the lot, sparkplugs, coilpacks, timing, and pump and write it off as a 100k service. Thanks for the info guys, ill post back once ive fixed the problem