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Discussion Starter #1 (Edited)
r33 gts.need tech info please.

had car a month or so. 50 odd k miles. hard acceleration car feels hesitant, lift off throttle slightly and car pulls better. motor totally standard. anyone any ideas?
 

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Hi Jake,
Welcome to the board :)

Is the hesitation around the 4.5-5k rpm mark ?

Probable cause is the spark plugs mate, some nice new iridiums gapped at .8mm will have you pulling like a train in no time.
 

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Discussion Starter #3
iridium spark plugs for r33 gts

cheers jason o, just fitted car with ngk pfr 6a plugs which were in previous and was hesitant then around 4-5000 revs and still is. who supplies iridium plugs and are they worth the difference. also leaded or super unleaded?
 

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HKS, Greddy, Blitz all offer Iridium plugs although most are made by NGK.

Super unleaded is probably the minimum with most ppl using Optimax.
 

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I had a misfire at high revs with standard plugs, cured with a change to GReddy Iridium plugs... any of the tuners mentioned on here can generally supply, only a pound or two more than the platiniums

Super unleaded IS A MUST for Skylines

RonS
 

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Optimax

Guys, it's got to be Shell Optimax for best performance on the road, then add some Octane Booster for track running.
 

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Jake,
I had PFR6A's in my car and they did hesitate around the 4.5-5k rpm mark, even when gapped at 0.8mm, the iridiums definately cure it. Contact Rod Bell as he is the most local specialist for you, and he will be able to supply the iridiums.

Steve,
I regularly see more knock on my APEXi PFC when running Optimax than what I see when running BP Super UL.

I'm yet to be convinced of the sustainable quality of Shell Optimax, and FWIW Mycroft also is unsure of it's quality, just check the Octane Booster thread for his opinion.
 

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Jake,
Super Unleaded ONLY

Running with ordinary UL will cause detonation (knock) and will end up with you having a large bill to replace some melted pistons.

You may even find that poor fuel could be the cause of the hesitation, as the ECU will retard the ignition when it detects knock.

The stock ECU in the R33GTS25T ups the boost from 0.5bar to 0.7 bar at about 4.5k rpm, it changes the cam timing at this point too. This is the point the plugs seem to have a bit of bother maintaining a spark if the gaps are too big.

It may also be that your fuel filter could be blocked, and therefore not supplying a quick enough rise in fuel flow when the boost rises to 0.7bar.
 

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off topic a bit

I too am unsure about Optimax. I have been using it for the past 3 months, about a tank every 2 weeks, but last week I had to fill the tank with BP SUL and I think it felt a lot better.

Just my 2p worth, but what do I know I only own a GTSt :p
 
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