juddering/dump valve question.

[grim_d]

I have a question about my car which I'm hoping someone can shed some light on. If I'm driving along using part throttle and therefore not full boost and ease off the throttle the car judders a bit and the dump valve will release pressure in stages however if I fully come off the throttle sharpish it releases everything all at once with no juddering.

What causes this? something I could rectify or would I need to change my driving style and always let it dump completely? I was thinking maybe the spring for the dump valve could be at fault? Not sure what type of DV it has.

 

[gl3nn]

I would blank the dump valve off to try mate and see if still judders. if not then dumpvalve at fault

 

[keastygtir]

throw the dump valve away!

 

[grim_d]

Yeah if I take the dv off I imagine it wouldn't make it back on...

Still like to know the reason though. From a technical view.

 

[johnny gtir]

what dump valve ? some are adjustable or its a strong spring so COULD it be at partial throttle its not dumping properly and stalling turbo. I as always worded it crap but you get the idea ?

 

[grim_d]

Yeah I understand, I'll take a look at it when I'm off tomorrow, not had a proper look under the bonnet yet.

 

[johnny gtir]

I could be talking shit like usual was just a thought/theory

 

[red reading]

Mapped to suit driver, and you are probley getting slight reversion thru the z32 at light throttle causing a slight lean spot hence juddering, change your driving style and get rid of the dump valve, that car is so begging for more boost!

 

[grim_d]

Cheers Danny. I'll bin the dump valve, it's most noticeable on the motorway when trying to maintain a constant speed.

Dan said it will need a new power cable to the fuel pump before I can up the boost as it was leaning out when he was having it mapped at 1.6bar

 

[vss irvine]

You might need to check the tps voltage aswell.

 

[grim_d]

I'll check that out tomorrow as well.