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R34 - 1st/2nd Gears; Lower Boost Than Other Gears?

SS8_Gohan

By SS8_Gohan,
in Engines & Forced Induction

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SS8_Gohan Grand Master

SS8_Gohan

Posted
Posted

Hi everyone,

well, after having the car (R34 GT-T) sit it my garage for 1 year i've finally got it registered!

anywho... i think i'm having some boost issues in 1st and 2nd gears?

After compliance car was driven from Syd to Melb. Compliance includes new fuel/air/oil filters i believe... will have to double check fuel filter.

So it's done 1000km's from that trip and very little driving since until now. So i'm guessing the filters are ok, checked oil as well, looks fine.

Now the weird thing with this boost thing is that gears 3, 4 and 5 are a lot more responise and smooth. This shows on the stock boost guage.

Gears 1 and 2 will barely or not at all go over '0'. Where as gears 3, 4 and 5 will reach the 3/4 mark easily, and very smoothly. This is accelarting and shifting at the same RPM for each gear, i tried taking each gear to 3000rpm, 3500, 4000, and 4500rpm, same thing. 1st/2nd gears won't get the needle on the stock guage to go over the 0 mark.

Now the extra weird thing is that every now and then, VERY rarely, 2nd gear WILL hit the 3/4 mark on the boost guage and different feeling is very noticable.

I'm really new to the whole turbo game, so i'm not sure what's happen, but you can tell that 1st/2nd gear don't seem to be quite on song when it comes to boost.

Anyways, would love to see what some of you guys'n'gals think :D

cheers

chinny

SS8_Gohan Grand Master

SS8_Gohan

Posted
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Posted

ok, well at least you guys cleared up the same boost in each gear... i was wondering if the ecu had a lower boost setting for the first 2 gears for whatever stupid reason, i thought that was a bit of a stretch.

aftermarket turbo? i'm 99% sure it's not... it was a RAWS test vehicle, so would have to be VERY stock. And never ever mention of it when i bought it, or by compliance workshop.

the weird thing is when sometimes 2nd does get the boost needle hitting the 3/4 mark of the stock GT-T boost guage. And i just took it for a spin before and 1st was also getting 3/4 mark!! but then went back to not getting there for 1st and 2nd gears. No trouble as yet for 3,4,5th gears.

so the ECU could be playing funny buggers? restricting boost maybe?

paulr33 Grand Master

paulr33

Posted
Posted

as ash said load makes the turbo come on better, ie going up a hill in first or second should bright it on nicely, going down a hill on the other hand will not. the ecu will have dual stage boost buts its likely to be switchable from say 5psi to 7psi or 8psi after say 4000rpm or something to that affect

WazR32GTSt Grand Master

WazR32GTSt

Posted
Posted

i have similar experiences but not as low in first couple of gears, more just 1 or 2 psi difference:

in my R32 i find that i get slightly more boost in 3rd at 2500rpm accelerating than i do flat out in 1st at about 4000rpm

i just thought it was related to load?

nF Collaborator

nF

Posted
Posted
but Ash said "you should make the same boost in all gears"...

theres a boost control solenoid inline with the wastegate actuator line with r33/r34 skylines. the standard actuator is set to something like 5 psi, and to achieve the higher boost (is it 7psi?) it will bleed off a bit of the air.

atleast in s15s, you don't get full boost in 1st gear. this may not be the case in r34s/r33s. r32s run on wastegate actuator only. (which is set to ~10)

nuffsaid Veteran

nuffsaid

Posted
Posted

You should get to 0.5 at least on 1st gear, I usually do.

2nd gear definately hit full boost.

Note on a stock R34, you should see maybe 0.5 cold nights for full boost.

If you have a full exhaust, then the 3/4 mark is expected.

Thats what I found on mine anyways

Abo Bob Grand Master

Abo Bob

Posted
Posted

I think you should get full boost while running stock in first gear but it is by no means a given further down the modification path but that doesn't matter because I think there is something wrong with your car.

I would go over every hose and pipe in the intake system and check for things that haven't been tightened up properly. I wouldn't be surprised if one of your hose clamps was not tightened up properly or something like that.

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