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Hi Guys,
I know there many boost solenoid topics and I've read most of them so I understand the general symptoms related to them. I suspect mine isn't quite right, but I'm a little unsure if the issue is just in my head.

Firstly as a bit of background - I have the MP260 map and cat back (fitted August 2012) so I know the car will be boosting differently to standard. Also I don't drive it daily so sometimes it can sit in the garage for two weeks without a drive.

My problem is that recently the car has felt a little slow in day to day driving (it got plenty of use over Christmas/new year) so I started to pay more attention to the boost gauge and performed a few tests. It appears that on anything up to about 70% throttle pedal travel in 2nd/3rd/4th gears I'm only getting quarter boost right up into the 3000-4000rpm range.
I can make the car achieve maximum boost but to do this requires me to consciously push the accelerator down towards the carpet (100%) and it isn't very controlled; I much prefer to drive smoothly and build the accelerator pressure as the revs rise past 2000rpm etc.

Should I be able to control the boost better when wanting to make brisk progress 40-60% throttle travel? I seem to remember I could, but I'm doubting myself because the boost gauge isn't something I normally watch.

Thanks in advance to any replies.

Mike.
 

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Il try answer your question lol,

You should be able to control the boost upto the 1/4 mark in any gear. After 1/4 as far as i know it just goes straight to 1/2. I have never seen it in between. For me to get full boost (1/2) you have to floor it, thought that woulda been normal tbh. If your doing 40-60% throttle you wont get any higher than 1/4
 

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Can't comment on the Mountune map, but I know that with the Collins ones, throttle position is relative to boost. 50% throttle = 50% boost and so on.
 

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Not much experience myself here but I know the mp260 is quite a rapid map and so it boosts up high and fast, similar to how the DSCI maps are. I've diven a mp260 and I'm running the DSCI map at the moment and I find them similar. Up to 1/4 the boost can be controlled but once you press harder the boost kicks in harder and you feel that shove as it takes off, but there isn't much middle ground. It makes for a super fun map for just that sheer satisfaction of feeling the turbo kick in hard and being pushed back into your seat but it does unsettle the car a bit when fast cornering etc.

The only smooth map I know off where you really have control of the boost at all times is the Collins one and whilst it may not 'feel' as fast in reality it will be as you can keep the car planted at all times and are less likely to be caught out by chunk of torque kicking in. I have heard someone mention Mod X is smooth but not 100% on that one.
 

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Can't comment on the Mountune map, but I know that with the Collins ones, throttle position is relative to boost. 50% throttle = 50% boost and so on.
should be about right, yes.

for the OP - think about the way a turbo works, it is spun using exhaust gas. the more you press the throttle, the more air gets let into the engine, the more fuel it adds to the mixture and so the more exhuast gases you get. the more gases the faster the turbo spins, so the more boost you get. of course passed a certain percentage throttle you should achieve max boost without needing full throttle, but you get the idea.

of course the higher the revs the more cycles the engine does per min so the more gases the engine expells as well, so you need revs or throttle. turbos work better lower RPM to give low end torque, as thats king for in-gear acceleration, so throttle is your friend!

best way to drive a turbo, at full throttle.
 

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Discussion Starter · #6 ·
Thanks for all the responses guys. I agree with all the comments, I guess my point is that something feels like its changed and I shouldn't need 100% throttle to trigger the turbo into giving more than an indicated quarter boost on the gauge?
 

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Discussion Starter · #7 ·
Hi All,
Thought I'd follow this up with a little update for anyone searching forums for similar issues. This morning I switched the boost control solenoid for a new one by following the very helpful guide in the how to section of this wonderful site. Car is noticeably better, the tyres will now break traction in the dry in 2nd whereas before they wouldn't even do this in the wet; which was another reason I suspected something was up - don't get me wrong I don't normally drive to induce wheel spin but once I thought something was up I pushed the car to see if I could break traction as a test.
The boost gauge isn't showing much of a difference, I think it is moving to full boost earlier but there isn't much visible variance between 1/4 and full. I can feel the difference though, its much smoother coming onto boost and the torque and power build much earlier on with much more immediacy with less throttle input than was required before.

For £50 and a slightly scratched hand I believe it was well worth the effort to see if this solenoid fixed my issues...and thankfully it has


Cheers,
Mike.
 
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