not holding boost

[ChrisS]

Dont know if this is boost controller/wastegate/anything else related so any suggestions please. Controller is a HKS EVC4, 3071 turbo, emanage blue.

When boosting im getting an initial spike up to 1.5barish but then its dropping back to 1.3. have tried having a play around with the controler as i thought it might be as a result of the gain control been a little too aggressive. However, the controller isnt letting me access the gain control function to check what its set at. It spools v.quick, hitting full boost by 3700rpm.
Also on part throttle the boost is shooting straight up to max. Part throttle im also having an issue with the dump valve (HKS SSQ) releasing so i cant hold a part throttle, part boost. Its all or nothing. Any ideas what to try or look for or anyone had similar problems.

 

[GTIR-LOZ]

what do you mean by the dump valve releasing if its in the standard position with the standard vacuum feed off the black box behind the inlet then there is no way you could have vacuum there at part throttle i thought the ssqv uses boost to hold the valve closed then uses the vacuum on lift of to open the valve

 

[ChrisS]

what do you mean by the dump valve releasing if its in the standard position with the standard vacuum feed off the black box behind the inlet then there is no way you could have vacuum there at part throttle i thought the ssqv uses boost to hold the valve closed then uses the vacuum on lift of to open the valve

Probably not explained that part too well. It will be vacuum causing it to release.

What sort of symptoms would be caused by boost creep, or surge?

 

[GTIR-LOZ]

i understood that but there should be no vacuum there when you are on part throttle.

surge is where the boost increases and then drops back down, creep is where it increases past the boost limit slowly i believe

i am not familiar with the hks boost controllers sorry,

 

[ashills]

the dump valve is probably being forced open by the turbo spooling fast
change it for a stronger one or block it off
the boost surge then holding 1.3 maybe the limit of the actuator
what boost do u get when u turn the boost controller off

 

[ChrisS]

the boost surge then holding 1.3 maybe the limit of the actuator
what boost do u get when u turn the boost controller off

havent checked yet, will try and get out and do it tommorow. I have noticed that on the boost gauage the needle is moving slightlyup and down when pulling full boost, almost as if the controler is struggling to hold it steady at the set boost level. Did think this could be down to the actuator not being strong enough.

 

[ashills]

stick a bleed valve on it to test it thats all i have ever used on 3071 alot of electronic boost controllers struggle with them
also have you taken the feed to the boost controller from the stock place or just after the turbo (this is best)

 

[ChrisS]

Boost with the controller off is 0.7bar. holds this with no spikes or drop off.

 

[riske]

Sounds as though your boost controller is struggling to hold the set boost. Try adjusting it until you get problems and leave it at that until you can get a better controller.

 

[snoon]

your boost controller could have just given up.

My old blitz ID sbc gave up and my R was just boosting to whatever it fancied that day?!?!

From experience don't try and replace any parts on yours to fix the problem. I spent £130 IIRC on a new solenoid thinking it was that what had given up on mine but it was still knackered. Ended up buying a new boost controller in the end.

 

[ashills]

easy way to check use a bleed valve to see what boost you can safely hold with that so say u can hold 1.5 to red line u know its boost controller if it does same as now then its actuator and its its a .7 bar then sounds about what they are limited to all the 3071's ive had i get with a 1-1.2 bar actuator so it will run upto 2 bar at redline

 

[ChrisS]

easy way to check use a bleed valve to see what boost you can safely hold with that so say u can hold 1.5 to red line u know its boost controller if it does same as now then its actuator and its its a .7 bar then sounds about what they are limited to all the 3071's ive had i get with a 1-1.2 bar actuator so it will run upto 2 bar at redline

Have got a bleed valve kicking around somewhere so will give that a go. Had a quick look at how the controlers been plumbed in, looks a bit of a mess and half think the issue i have with the dump valve is also to do with where the vacume is taken off for the controller T'ing into the same pipe.