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Featured Replies

Hi had engine tuned few months ago now in 5th gear when on boost you can feel the boost fluctuat,you can also see it on boost gauge. Any help would be great.


  • Author

If I start building boost up boost n get just below 1bar it starts jumping up to bout 2bar.if I give it more throttle it stops.

If its fine in all other gears it does seem a bit odd.  Boost spiking to 2 bar is very dangerous!  Has it been doing it ever since the map or just recent?  Id def get on the phone to the mapper and ask them.


What where your mapping goals ? How much did the mapper wind the boost up to &do you have a two or three port soliniod Sounds like overboost as opposed to cut,

I'd start by checking wasetgate, boost solinoid & hoses all could be a culprit,

  • Author

I will do.thanks.as far as am aware he opened the turbo rite up.i think its a 2port,does any body know where to get wind deflectors for 2002 scoobie?


3 hours ago, Scoobyghost said:

Mine was due to hitting the limit. Wouldn't spike. Target was 1.3 I hit the limit 1.4bar.

Ok so your getting exactly what I have at the moment on the secondary, just fuel cut like a brick wall lol?  You getting it adjusted or just living with it?  

  • Author

Prob get it adjusted soon when get others mods done,av found some deflectors on eBay bout £80 plus £40 delivery from America

Mine was due to hitting the limit. Wouldn't spike. Target was 1.3 I hit the limit 1.4bar.

Ok so your getting exactly what I have at the moment on the secondary, just fuel cut like a brick wall lol?  You getting it adjusted or just living with it?  

Yeah it was like someone slammed brakes on. No, I contacted Dunc straight away and he came to my house to tweak the map. He increased my limit. I can hit 1.4bar in the top gears still it just doesn't cut anymore. Can't fault Duncan with the after care. Was with me within two weeks.


Normally a remap will be done with 3rd & 4th gear pulls but when under higher load conditions (in 5th , 6th, going uphill or even colder denser air) There's more pressure in the inlet manifold. This can cause a difference in of pressure in the boost control vac system. In turn creating a different boost pressure that the one set by the mapper and somtimes hitting the max pressure boost cut target set by him .

Hence why my mapper tweeks the map at different driving conditions and throttle positions after each map [emoji6]

If it's not broke .....upgrade it 😊

I guess it's a downfall of dyno mapping. I'd only get it 110+ in 4th so right up high in the rev range like yourself Geoff.

Just get it mapped to come in earlier [emoji12]

Mine wheezes like an asthmatic donkey past 5k so no point going any further, almost like I'm driving a diesel [emoji23]

Should always be road tested even if dyno mapped, any mapper not doing a road test is one to avoid. Also so post map boost cut shouldn't be an issue, if so need to go back to the mapper and get them to fix it.

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