Help Please.

[massacre6969]

Hey peeps!

Iv got a bit of a problem.

I have a Nissan Skyline GTST r33 s2.

Basic mods front mount,fuel pump etc etc. Now i have a Greddy profec b spec II. My last boost peak is 7.5 - 8psi but my boost gauge is registering around 11psi. My car feels laggy. But if i set it so my car is running 11psi on last boost from greddy boost controller its much more responsive and feels right but it registers on the gauge as 14psi..I dont want to do damage.Iv been told to go off the gauge and some say the boost controller.. Im after 11-12psi. If anyone has similar mods whos running 11-12psi on a greddy profec b spec II . It would be great if i could get the settings for a starting point. i know all cars are different etc but im after a rough idea. SET. SET GAIN. GAIN. etc. Surely someone is running 12psi on a greddy profec b or has a good idea what settings are roughly right.. Help much appreciated.. thanks!

[Hanaldo]

What brand gauge is it? Where is the gauge tee'd into and where is the boost controller tee'd into?

If it's just a cheap no-name gauge, I'd trust the Profec. You didn't mention having any aftermarket engine management, so if that's the case then I highly doubt you are getting to 14psi without hitting R&R on the stock ECU.

[beenowened]

im running the basic mods aswell but also have a power fc. i have SET at from memory 46% and gain at 11% and that gets me 12.5psi

[massacre6969]

yeh basic mods..HKS F con S. .ok well 46% and gain 11% tells me that the boost gauge is out.( unsure of the brand) il check tomorrow. but 34% and gain on %7 gets me 11psi on the gauge but only 7.5 on the greddy.. also what is ur SET GAIN (start boost) set to..

Thanks heaps

[beenowened]

ok i just went out and checked it is SET 39% ( i dunno why i thought 46%) SET GAIN at 94 in psi mode and GAIN 11%. and that shows up around 12.5 on the greddy its moves a little other side though so it isnt set up perfect

[DVS JEZ]

Rather than reading the peak boost try reading the actual boost when its boosting. If u dont feel confident to do this get someone else to watch it while u drive

[massacre6969]

Thanks Beenowned.. And thats probly a good idea DVS..I had it around 37% and Those settings will read roughly 14 - 15psi on my boost gauge though? do u think that would be safe to run those settings maybe a fraction lower as im after 11-12psi. Even though my gauge is telling me higher...

[massacre6969]

Pro-Comp ultra - lite boost gauge.

[DVS JEZ]

Its weird that they are reading differently. Check the install and where they get there boost signals from. Most of mine i run the same line into the cabin then tee off for both the boost gauge and the profec b.

[SargeRX8]

Thanks Beenowned.. And thats probly a good idea DVS..I had it around 37% and Those settings will read roughly 14 - 15psi on my boost gauge though? do u think that would be safe to run those settings maybe a fraction lower as im after 11-12psi. Even though my gauge is telling me higher...

37% on the stock actuator won't give anywhere near 15psi.... I've got a 8psi actuator and the same boost controller set at 100% and the most boost I've seem was 12 psi, maybe one or two 13psi spikes.

[Hanaldo]

37% on the stock actuator won't give anywhere near 15psi.... I've got a 8psi actuator and the same boost controller set at 100% and the most boost I've seem was 12 psi, maybe one or two 13psi spikes.

Yeh that's weird though, mine was set at 66% when I had my stock actuator, that was 14psi.

[myRB25DETT]

Yeh that's weird though, mine was set at 66% when I had my stock actuator, that was 14psi.

^^^ same mine... 66% SET = 14 psi ....Get a good boost gauge.. Dnt get el cheapo..

[SargeRX8]

My stock actuator was leaking lol so I could never set it right. 14% saw 12psi one day and no more than 8.4 another.

[Hanaldo]

My stock actuator was leaking lol so I could never set it right. 14% saw 12psi one day and no more than 8.4 another.

Silly example then

But I agree with your point anyway, 37% wouldn't be 15psi.

[massacre6969]

If I turn the greedy unit to 0%. which is off or I turn the whole unit off. I get about 8psi and creeps to 10psi. Shouldn't it registers at 6psi(stock boost).

[djvoodoo]

^^^ same mine... 66% SET = 14 psi ....Get a good boost gauge.. Dnt get el cheapo..

To the fellas with the R34's. Fairly close to my set up too. But the 34 turbo is slightly larger so can't really compare to the 32 turbo characteristics.

my set is 56% gain 17% and set boost at 92. Peak reading on boost greddy unit was 13, but on boost gauge reads 14

[Hanaldo]

If I turn the greedy unit to 0%. which is off or I turn the whole unit off. I get about 8psi and creeps to 10psi. Shouldn't it registers at 6psi(stock boost).

About normal if you have a full 3"+ turbo back exhaust and pod/panel filter.

To the fellas with the R34's. Fairly close to my set up too. But the 34 turbo is slightly larger so can't really compare to the 32 turbo characteristics.

my set is 56% gain 17% and set boost at 92. Peak reading on boost greddy unit was 13, but on boost gauge reads 14

That's true... I still don't think it will be 15psi at 37% though. Only have experience with my setup though so I couldn't be sure.

OP, do what Jez suggested and have someone watch the gauges while you are driving. You might even want to get your car back into your tuner so they can double check the AFR's; wouldn't take long for them to do so shouldn't cost much.