GolfGTIforum.co.uk

Model specific boards => Golf mk4 => Topic started by: Ajh_91 on 26 June 2012, 09:25

Title: Boost loss when quick gear change
Post by: Ajh_91 on 26 June 2012, 09:25
Hi guys, right ive got this problem thats baffling me.. My car has been remapped to 185bhp.
It boost to 20psi, when i quick gear change it will only boost to 10 psi.. Yet if i take foot fully off throttle for 1 second and back on it will hit full boost without fail and hold there ?!?
If anyone one has any ideas it would be a great help, cheers
Title: Re: Boost loss when quick gear change
Post by: DunnDeal12 on 26 June 2012, 10:57
if thats baffling you then your baffling me :huh:
Title: Re: Boost loss when quick gear change
Post by: Xtrhardcore on 26 June 2012, 16:36
Checked your Actuator?
Title: Re: Boost loss when quick gear change
Post by: Ajh_91 on 26 June 2012, 16:59
I havent .. How do i go about checking it ?  Like what do i have to look out for ?
Title: Re: Boost loss when quick gear change
Post by: Ajh_91 on 26 June 2012, 18:18
Thing is if i slow gear change or known as "granny shifting" it will boost up perfectly all the time every time, so as quick gear change im likly to see only 10 psi surly if it was the actuator it would do 10psi all the time ?
Title: Re: Boost loss when quick gear change
Post by: cooki2 on 26 June 2012, 20:44
Surley there is no need to change gear really quick though? Y not just change gear like a normal person then u won't have the problem?
Title: Re: Boost loss when quick gear change
Post by: Ajh_91 on 26 June 2012, 21:18
Because for me to shift and maintain the 20 psi boost to next gear, my revs drop 2000 rpm... That isnt a normal gear change.. Hence the term "granny shift".. So any ideas guys ?
Title: Re: Boost loss when quick gear change
Post by: Wazzzer on 26 June 2012, 21:25
you will never maintain positive pressure when you change gear, it will always drop (unless you have anti lag)
Title: Re: Boost loss when quick gear change
Post by: mcgee9t2 on 26 June 2012, 22:13
only way to keep boost up is to install an antilag system

edit. didnt read any of the replys, already beeten to the answer by was
Title: Re: Boost loss when quick gear change
Post by: Ajh_91 on 26 June 2012, 22:54
Okie..  Im is secong gear accelarating (boost gauge is showing 20psi peak, holding 18psi), shift gear to 3rd (normal speed - quick shift) in 3rd gear and it will only boost to 10psi and hold at 10psi, let throttle fully off for 1 second, full throttle again and boost straight to 20psi.

Okie..  Im is secong gear accelarating (boost gauge is showing 20psi peak, holding 18psi), shift gear to (granny shift (2-3 seconds)) in 3rd gear and it will boost straight to 20psi.

I cant put it no clearer the that, it only happens when i change gear normal speed or i change gear fast (giving the car some power down the dual carridge way)
Title: Re: Boost loss when quick gear change
Post by: jamie1989 on 26 June 2012, 23:00
Sounds like map to me??
Unless its maybe a actuator problem?

When shifting in 2nd the change into 3rd @ 6500revs for example in 3rd gear with your map maybe its at 10-12 psi.

As with my R-Tech remap the peak is around 3000k I believe then holds boost but will drop towards redline,
Does that make sence?

Your wating a second and the revs drop below 3000k for example you floor it, it will peak again upto 20psi?
Title: Re: Boost loss when quick gear change
Post by: Dave_IOW on 26 June 2012, 23:04
Mine did this bud and never got to the bottom of it, speedy gear change and would feel absolutely awful, deaccellerate for a second and all was well, i have no idea but can assure you, I also had exactly the same thing and know what your trying to get at!
Title: Re: Boost loss when quick gear change
Post by: jamie1989 on 26 June 2012, 23:10
Maybe not the remap then as Dave you run a R-Tech map dont you?
Title: Re: Boost loss when quick gear change
Post by: Dave_IOW on 26 June 2012, 23:19
Yeah, never got to the bottom of it, engine will be in mk2 and running soon, but should have a new map on by then.

Really have NO idea what caused it though, thought might be either 007 spring or actuator spring not having time to shut, but think that was just clutching at straws..

Sorry can't help bud, but would be interested to know if you fix it..
Title: Re: Boost loss when quick gear change
Post by: Scott D on 27 June 2012, 01:23
I've had this happen on a few occasions  - quick gear change when giving it some then almost feels like gone into limp mode, off the throttle and back on boosts as normal.

Had a duff MAP sensor which eventually completely failed and registered fault codes, replaced and not had a problem since.
Title: Re: Boost loss when quick gear change
Post by: Dave_IOW on 27 June 2012, 07:24
Not sure what engine OP has, but I have an AGU so no MAP sensor   :sad:

Exactly same symptoms though  :huh: