My ISV is bleeding off boost

[olly elworthy 0]

hi ya im running sns chip and 68mm pulley, last couple days it seems like my isv is bleeding off my boost at about 5950 rpm as the car looses power of power all of a sudden ther these last few days when the mornings have been really cold, seems to co-inside with the car reaching just in excess 15psi of boost,,

how can i stop this? retard the timing a little or richen the fuel mixture up a bit on the CO pot? :?: or just keep the revs down a bit?

this is a new thing as she usually pulls cleanly to 6100 rpm easily,,

[golfg60 0]

6100 rpm...sheesh!! Am i being over careful by not revving mine that hard?

[Supercharged 2]

That maybe when the MAP sensor kicks in...? G-man will know...

[olly elworthy 0]

maybe i am revving her a bit hard then?

[golfg60 0]

i don't know if you are mate, to be honest i don't know that much about the G60 engine yet but i'm thinking that maybe i should push mine harder then??

[swfblade 0]

Personally, I never take take mine above about 5500 - 5800. Max power for a G60 is at 5600 anyway, so theres little point going above that i would have thought. And surely you want to compromise between power and max torque, so keeping in the max torque would be better for acceleration as well? (4000 - 5500)

[olly elworthy 0]

Personally, I never take take mine above about 5500 - 5800. Max power for a G60 is at 5600 anyway, so theres little point going above that i would have thought. And surely you want to compromise between power and max torque, so keeping in the max torque would be better for acceleration as well? (4000 - 5500)

 

ill try that, seems strange though that it was pulling all the way round fine until this week,,

[swfblade 0]

it may well feel like its pulling fine, but u'll get better accelleration if you keep it in the power ;)

[Guest]

I'm sure you realize this but the ISV on the G60 serves a duel purpose, it is used to control the air bypassing the throttle plates on idle and it is used to control the boost on the top end of the rev range as well. Have you heard of a G60 ISV reroute? This redirects the ISV from the intake of the charger to the intercooler pipe going into the throttle body and thus can't bleed off boost. You can see in this pic how easy it would be to make...

 

ISV Reroute

 

Hopefully this is what you need and there is not an underlying problem.

 

Cheers, Dennis

[Henny 0]

Re-routing the ISV is potentially VERY dangerous for your engine... :|

 

The reason that the ECU causes the ISV to vent (not leak, it does it purposely!) is to prevent the boost from going past the point where the fuelling/timing map in the ECU knows what to do... By removing this safety measure, you're effectively allowing the engine to overboost and therefore run lean... At high revs, running lean is gonna mean that your engine ain't gonna last long before you melt something crucial and end up with a very dead engine... :|

 

Talk to Darren about this before you end up blowing up your engine... 8)

[olly elworthy 0]

hmm gonna keep a close eye on the air fuel and boost gauge on the way home see if i can fathom it out,,

then check all my vac hoses etc, could be the start of a simple boost leak or something,

my charger silencer box is a little suspect but should be getting an RSR outlet form darren as soon as they are ready.

also im still running the carbon canister, so maybe ill take that off at the weekend to tidy it all up a bit, another place where i could get a leak.

[olly elworthy 0]

Re-routing the ISV is potentially VERY dangerous for your engine... :|

 

The reason that the ECU causes the ISV to vent (not leak, it does it purposely!) is to prevent the boost from going past the point where the fuelling/timing map in the ECU knows what to do... By removing this safety measure, you're effectively allowing the engine to overboost and therefore run lean... At high revs, running lean is gonna mean that your engine ain't gonna last long before you melt something crucial and end up with a very dead engine... :|

 

Talk to Darren about this before you end up blowing up your engine... 8)

 

read darrens post a while ago about re-routing the isv, sounds dodgy,,

[olly elworthy 0]

it may well feel like its pulling fine, but u'll get better accelleration if you keep it in the power ;)

 

been driving about last night and thismorning abs changing up at about 5700 revs and as you say it is quicker,,, :wink:

[vwfastg60 0]

I am also a high reving g60 fan and also ran in to this. If you look over seas you can find that TT makes a one way valve for the isv I did that and the ISV reroute and to this day the only problem i hav had was because i was running a 58mm pulley on the charger. pics of the motor with ISV reroute

 

I will get a better pic tomorrow