# Boost pressure



## LAT (Aug 15, 2013)

Hey guys,

I'll apologise as this might be long winded.

I normally get to drive my Gtr most weekends and driving a 5 series diesel during the week I obviously feel the goodness of the Gtr when I get in it. Last night I drove the Gtr for the first time since the weekend before and it felt really sluggish.

I bought the car under the impression it was completely stock, but noticed that there was a receipt from litchfield for a down pipe. My friend has a stage 1 Gtr and said 'tell you what, I'll try to see if I can fiddle with the cruise control button to see whether or not I can change the map'. This was last weekend and not driven the car since, until last night.

Can anyone let me know the sequence please so that I can give it ago to change it back? 

Before when I drove the car it felt that quick that I couldn't look down at the boost gauge to see what boost it was running, last night it felt like I had plenty of time, it's running 0.5 bar. Is this stock boost pressure? What I also noticed was that on half throttle looking at the boost gauge it'll fluctuate massively from 0 to minus then back to positive.

So my question is that, do you think my friend has changed the map by mistake or could there be another issue?

Sorry for the long read, thanks in advance.


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## jrattan (Oct 23, 2014)

Hi mate

Hopefully these two threads may help

litchfield map switching guide v4

https://r.tapatalk.com/shareLink?ur...share_tid=409217&share_fid=44370&share_type=t

http://www.gtr.co.uk/forum/431794-no-boost.html#/forumsite/21025/topics/431794?page=1


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## Stealth69 (Jan 6, 2005)

Quick way - get in the car, start the engine, get the boost gauge in the mfd, make sure cruise is off and then push the cruise adjust button up, you should see the boost gauge creeping up with every push up


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## LAT (Aug 15, 2013)

Thanks guys! Really appreciate it. I hope it's just that the map has been changed


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## Stealth69 (Jan 6, 2005)

I don't imagine much else could have changed if he was sat in the car dicking around and it was fine before hand  ......... Unless you have nice or rats around your way lol


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## LAT (Aug 15, 2013)

Yeah I hear what you're saying, so does anyone know if half a bar is stock boost pressure?


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## LAT (Aug 15, 2013)

Hey guys, I've changed I guess my car is mapped, I've changed the map to number 3, which is 99. As I'm changing my boost. What amount of boost can I run safely? Max boost on the gauge is 1,25 bar


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## jrattan (Oct 23, 2014)

The maximum boost you can select should be safe as it should've been restricted by the tuner when mapping your car. Probably 1.5 bar


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## Stealth69 (Jan 6, 2005)

1.4 is the most you should really run, depends what stage your car is actually at, if it's had the downpipes down I'd suspect it's a lot higher than you think! 1.35-1.4 on the higher tunes cars puts the car at around its theoretical safety limit for gearbox


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## LAT (Aug 15, 2013)

Thanks guys, max looks like 1.25 bar


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## LAT (Aug 15, 2013)

Ahh that feels better  

Thanks for all your help guys!


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## snuffy (Mar 26, 2014)

I did that the first time I had mine mapped (Ecutek). I fiddled with the 4 settings and the managed to limit the boost to 0.5 bar I think. So after I'd worked out how to set it back to normal I've not fiddled with it since !


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## Stealth69 (Jan 6, 2005)

Yaaaaaaaaay!! Well done buster


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## LAT (Aug 15, 2013)

snuffy said:


> I did that the first time I had mine mapped (Ecutek). I fiddled with the 4 settings and the managed to limit the boost to 0.5 bar I think. So after I'd worked out how to set it back to normal I've not fiddled with it since !




Don't worry I won't be changing it again!


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## Stealth69 (Jan 6, 2005)

You know how to now, that makes you a professional lol don't be scared of messing around, you can't do a great deal of damage without an ecutek cable


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## LAT (Aug 15, 2013)

That's true, I think the settings are staying as is.


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## jrattan (Oct 23, 2014)

Glad it's sorted - I thought mins was broken the first time it happened too lol


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## mindlessoath (Nov 30, 2007)

what's octane is your map for? have you done any data logging to show your tuner to make sure its all in check?


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## Trevgtr (Dec 24, 2012)

LAT said:


> Yeah I hear what you're saying, so does anyone know if half a bar is stock boost pressure?


Stock 09-10 models is 0.8 bar, stock 11-15 models is 0.9 bar, my 16 boosts at 1 bar.

Sounds like you have a stage 2 map, which is exhaust, air filters and 1.2 bar.

If you're into launching you should be able to control launch rpm too, by engaging launch mode then toggling the cruise toggle up or down. Standard launch is 4k rpm, 3.7 feels better and is less strain.

You can probaby do rolling lauches too (with cruise button) if that's your thing


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## LAT (Aug 15, 2013)

See that sounds interesting as I've not looked under the car to see whether the full exhaust has changed. The air filters are still in the same location and housing, they're not in the front bumper, is that right?


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## LAT (Aug 15, 2013)

jrattan said:


> Glad it's sorted - I thought mins was broken the first time it happened too lol


Happened to you too then haha


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## Trevgtr (Dec 24, 2012)

LAT said:


> See that sounds interesting as I've not looked under the car to see whether the full exhaust has changed. The air filters are still in the same location and housing, they're not in the front bumper, is that right?


Yep, they're probably K&N though, easy to unclip and look, takes approx 5 seconds per side


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## jrattan (Oct 23, 2014)

Just to complicate matters even more... I ran a stage 1 with k&n air filters as I upgraded to them during service so I didn't have to change them again.
Easiest way is probably to phone the tuner or plug it in if someone has a cable.


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## LAT (Aug 15, 2013)

I'll check when I'm home at the weekend, best bet is to go through the paperwork and ring the tuner.


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## Chou (Apr 18, 2005)

The MY15 GTR I've been to see boosts to 1.2 bar, it's 'supposedlay' completely stock and has only been to Nissan for services.

Is that stock boost?


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## Stealth69 (Jan 6, 2005)

nope as stated, the norm for that year is around .9bar...... if it is hitting 1.2 bar you are either seeing it over swinging and then dropping back to .9bar or its not standard


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## Chou (Apr 18, 2005)

Stealth69 said:


> nope as stated, the norm for that year is around .9bar...... if it is hitting 1.2 bar you are either seeing it over swinging and then dropping back to .9bar or its not standard


What would you suggest has been done to hit 1.2 bar.

All looks stock on face value, but the exhaust note seems deeper.

I'll start a new thread as it has Alcon discs on the front from what I can see, maybe a forum car that was part ex'd


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## Stealth69 (Jan 6, 2005)

I think stage1-2 are around that pressure....... I think, I don't know in depth specifics for each stage but that would certainly give you the bhp hike that tuners claim for that level of tune

Possibly just y-pipe and remap....... With engine on and cruise off hold the cancel button does the Rev and/or coolant needle drop? And then can you push the up and down button on the cruise to adjust the Rev counter? That will tell you if anything at all has been done mapping wise. (Unless it was Cobb) 

Defo on stock injectors, possible drop in filters


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## LAT (Aug 15, 2013)

So then guys, had a quick look at my filters, standard or aftermarket? 

As stated before, my car is running 1.25 bar, stage 1 or 2? 

Thanks again!


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## jaapio (Mar 11, 2015)

standard


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## Trevgtr (Dec 24, 2012)

Somebody may have removed the K&N filters and replaced with stock when they sold the car to the dealer.

It's probably mapped as a stage 2, stage 1 is 1.1 bar.

You should be able to see the Y pipe if you can get underneath a bit.


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## LAT (Aug 15, 2013)

I need to have a look really, anything to look for specifically?


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## Trevgtr (Dec 24, 2012)

Ideally you need to look with the car on a ramp, but you could probably initially check by laying on the floor by drivers door and reaching underneath. The stock secondary cat is a big old lump (google a picture of it) and if removed you will be able to feel a pipe which splits into 2, hence called a Y pipe. 

Most common Y pipe is Milltek, could be res or non-res, you need to get under to check it out.


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## LAT (Aug 15, 2013)

Brill, I'll have a gander over the weekend


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## jrattan (Oct 23, 2014)

I'd still get it checked out by the tuner even if it does have a Y pipe.
The air filters are used for greater air flow and hence run the increased performance. I personally wouldn't be comfortable running a mapped car without the correct parts which are for that tune.
Although I'm not a mechanic so maybe someone could clarify? Maybe the air filters don't matter? But I know at least stage 1 is upgraded air filters


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## LAT (Aug 15, 2013)

Totally understand what you're saying. If anything I'll just pick some filters up and drop them in.


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