Boost issues


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fire_king

Speed Equip Auto Centre
Joined
Jun 5, 2009
Messages
214
Tried searching can't seem to find any info. I had the car mapped a few months back running .5bar (7psi) it was running fine and holding boost. Last week it was only getting to .4 bar and has been ever since I can't seem to find what's causing this. It builds boost fast and still pulls. So far i have done the following

Boost leak test and no leaks at all.
Removed the vacuum pipe coming off the waste gate and blocked it off it was only hitting .5bar
Adjusted actuator rod left vacuum pipe disconnected and it started over boosting
With the actuator rod adjusted and vacuum pipe connected it was almost hitting .5bar but after 5 mins off driving was back at .4 bar could the actuator be the issue?
The turbo is fine with no shaft play.
Removed downpipe and checked actuator flap on turbo open closes fine.

Any help would be appreciated.

Thanks
 
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Sounds like weak wastegate spring or your losing boost somewhere. Have you a BOV?
 
Vtec6000 said:
Sounds like weak wastegate spring or your losing boost somewhere. Have you a BOV?
Click to expand...

Thanks for the reply. I have a hks ssqv bov fitted also tried my blitz bov both off these are fine and not leaking and still have the issue. I have done a boost leak test pressurised the system and found no leaks at all including the bov. So you think it could be the actuator thats weak? Could it be anything else?
 
If there is no leak post or pre turbo then the actuator is only thing that is controlling the boost level so problem must lie there
 
If you pulled the actuator line off and it over boosted the actuator cant be broke, tee in a brass bleed valve into this line and bleed off a little boost and then see if it holds. Do you have an electronic boost controller?
 
rs250nut said:
If you pulled the actuator line off and it over boosted the actuator cant be broke, tee in a brass bleed valve into this line and bleed off a little boost and then see if it holds. Do you have an electronic boost controller?
Click to expand...

Hi thanks for the reply

I Removed the vacuum pipe from the actuator tested it car did not go over .5bar

I adjusted the actuator rod ( shortening it ) with the pipe disconnected tested it again this time it over boosted connected the actuator vacuum pipe and it went just under .5 bar after 5 minutes of driving it went back to .4bar.

I adjusted the actuator rod again ( shortening it ) a little more to see if it holds boost at .5 and now the car is over boosting. There is no boost leaks at all I have triple checked. Also not running a boost controller.

Just to add
Before adjusting the actuator it sounded like there was a leak on or off boost I could hear this clearly from 0 to .2bar boost higher revs it was harder to tell since adjusting the actuator this noise is no longer coming not sure if that will help in what it could be.

Could this be a bad actuator or something else?

Thanks for your time
 
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I have a hks ssqv bov fitted also tested with a blitz bov. None off the bovs were leaking when I done a boost leak test.
 
A update adjusted the actuator its now boosting to .5bar in every gear only issue am having now is it drops off boost very little at high rpm and stays just under .5bar any ideas? seems like a bad actuator to me
 
You will always get to a certain boost for it to drop off slighty. its nothing to worry about, its pretty normal.
 
glad you got it sorted, unless you have a good size turbo its normal to fall off boost at higher rpm's, our honda engines rev high :D
 
Thing is boost never use to drop off before this problem always use to hold at .5 bar now it drops off and stays inbetween .4 .5 bar. Also sometimes it will go a little over .5 bar in 1st gear
 
the ambient temperature plays a big roll in this also though, my car builds in extra 1-2 psi in the winter time and .5-2 psi less in the summer time :p
 
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