Throttle/Power Issue

[Axeboy]

Gents

Just a quickie, ive noticed over the past few weeks that my car has a strange issue.

Basically, if I give it some throttle then pull off the pedal, it experiences more drop in power than id expect.

Its not a big issue as such, it feels like a very mild fuel cut.

It doesnt really effect the performance, but i can still feel it.


The only thing ive changed recently is adding a new recirculating valve, could it be related to the spring strength on this?

Any thoughts gents?

[ritch_w]

couldnt be the throttle cable?

do u have another dump valve to test with?

try a softer spring?

[Axeboy]

I think tomorrow ill try changing the spring tension (its adjustable)

Failing that ill just blank off the inlet and try it...

[Nick Mann]

Mine does that, medium to light throttle and then a gentle lift. I then get a quick yank backwards as the engine tries to work out what's going on. It could be a very quick stab of fuel cut, but a strange time to get it? I have never explained it either - I just live with it. If I move my foot gently under those conditions I can avoid it altogether.

Incidentally, I use a HKS SSQV, so if your problem is the recirc, it's not the same issue as me!

[Axeboy]

Thats it Nick...

Same issue, but not a problem as such...

I'll try a few things tomorrow and report back...

[mpau009]

Mine does that, medium to light throttle and then a gentle lift. I then get a quick yank backwards as the engine tries to work out what's going on. It could be a very quick stab of fuel cut, but a strange time to get it? I have never explained it either - I just live with it. If I move my foot gently under those conditions I can avoid it altogether.

Incidentally, I use a HKS SSQV, so if your problem is the recirc, it's not the same issue as me!

I think i have the same problem sometimes with my VTA bov, it almost feels like the BOV should have opened to let some pressure out, but didnt, and i get a bit of a shudder. Like you say on medium boost when you lift off slightly, especially on the motorway or similar

I tried backing the spring pressure off a bit, and it seems to have helped the shudder, but then i run into idle issues when coming off boost, i think its a bit of a balancing act..

[william]

I had the same problem after fitting a GFB BOV. The problem did get better after slacking off the spring tension although it did not disappear completely. It is as Mpau said - you need to play around a bit to find the best compromise setting. I avoid the problem by not easing off the throttle gradually but quickly get off it - you can hear the valve venting then and the problem does not occur. It is apparently caused by the turbos stalling due to the induction pressure being higher then the pressure on the exhaust side of the turbos.

[Axeboy]

Ok, Update:


Been advised by my mechanic that its something else... now i cant remember the name exactly but it was some kind of Throttle Diaphragm..

He says he noticed this when he drove my car last, its supposed to ease the power when you lift off the throttle but its pooped and not releasing slowely...

[Nick Mann]

Let me know when you remember what it is!!

[Axeboy]

Well, im having mine replaced, so when i speak to him next ill let you know...