Yet another boost related question...

Got a Turbosmart boost tee from MSD - a nice little boost controller btw!
Plumbed it in between the comp housing and the actuator, got it to hit my desired 0.8bar of boost at around 3,300rpm. But by the time i get to 4,000-4,500rpm the boost drops to 0.5bar. Seems alot of peaking to me.

Any 1 had a similar problem, ive read maybe its a good idea to run the boost controller off the inlet manifold rather than the comp housing on the turbo.

Thanks in advance!

 

remove your turbo elbow and check that your exhaust housing isnt craked around the wastegate.

 

could be wastegate creep if the actuator is a little soft, quite modest boost level, so that could be the case

 

Checked the elbow when i fitted it... altho for the sake of it i could re-check it!
The actuator is a brand new -31...
Ive got 1 side of the iacv going to atmosphere, to suck in fresh air. So only 1 side of it is pressurised, could it be getting pushed open by the boost and leaking air out?

 

yes! it needs piped into the turbo side of the butterfly throttle, definatly

 

i thought -31 actuators were 1 bar minimum?

 

oops! Boost pressure will be going to atmosphere as these are not air tight and do not always close fully either!

 

10psi mate, -34 is 14.5psi, but this is at the compressor housing not inlet manifold (in most cases) so there will be drop.

 

The actuator is wound up quite alot... Got 2-3 threads left. Lifts at 12psi with a mitivac, seems strange to me.
I'll re-pipe the iacv, into the crossover and see how it goes then... If this cures it im gonna be soo happy, as its been baffling me with boost drop/irregular boost for ages!

 

educated

 

is your amal valve plumed in??

with out any form of electrical control, or a properly sprung wastegate to the pressure you want your always going to get a bit of peak then hold differential.

try connecting the amal valve back up then changing the jets in this to your desired boost.

 

you not read the begining?

 

I had the same issues with my AMAL valve, thats why i changed to a stand alone boost controller...
Ive re piped the IACV into the crossover pipe, boost seems abit more stable but isnt spot on.
When it 1st hits full boost, around 3,300rpm it peaks at nearly 1bar then slowly drops back to around 0.6bar now, i had to turn the controller down loads as it was over boosting with the IACV piped up the new way, so it has obviously made some difference!

What about piping the boost controller to the inlet manifold rather than the compressor housing? Also taking some pre-load off the wastegate.... As its wound up quite alot atm?

 

If you have no boost leaks, the turbo is good and the actuator is good then the only other thing it can be is something retarding the timing or your cam is heavily worn.
Piping the boost controller to the inlet will make no difference as it isnt an EBC running closed loop so isnt MAP aware.

 

Well cam and everything in the head look in pretty good nick when i gave the engine a freshen up before fitting it... Didnt measure the lobes mind you! It does feel like it needs a good setup tho - im stuck as for who to take it to!? Jano or Rallytec im thinking.
My reasoning for pipiing the mbc to the inlet, was to stop boost spiking so much. A google search revealed it to stabilise when the turbo comes on boost....?

 

Save your money and stop buying parts. Just get it tuned. All your Q's would be answered at the same time and it will stop you from getting random crap info off the net thats been handed down from random to random

 

hardly, both karlos and i have proven you wrong before oddchild

 

Ok Jano, When can i book it in?

 

is that classed as advertising?

 

Are you EFI or MFI I cant remember?

 

The reason this is done is that there will be a pressure difference between the compressor housing and the inlet manifold (things like your IC will cause a drop), so if your actuator is set to open at 10psi for example you may only be seeing 7psi (3psi loss through IC) at your manifold, where as if you pipe the actuator to the manifold then it will not open until your actually making 10psi at the inlet (as showing on your boost gauge).

 

Im on EFi, Karlos...
Well maybe ill give it a go, plumbing the boost controller to the inlet - might stop the boost peaking so much!?
Chaffe - Nah its not advertising, its advice lol!

 

What efi system are you on?

Not all advice is good advice.

Rob,

 

Don't feed it from after the throttle body.

Rick

 

ive used both mate. take it to jano

 

Rick - why not after the TB?
Rob DOHC- Fiesta Turbo OFAC...

Its got a stage 1 superchip 165 chip in it, stage 3 t3 with a -31 both brand new, and a turbosmart boost tee controlling the boost. Radtec FMIC, exhaust and filter. It hasnt been properly setup since the engines been in the car. Only the Idle CO adjusted!

 

because the system including boost controller and actuator is not supposed to see vacuum

 

If your on OFAC then there is no setting up to do, all you can do is adjust the base fuel pressure and idle CO, that will not cure your boost problem.

 

Took the car out again last nite, to have a fiddle with the boost...
After ive been cruising for a while when i bring it on boost it hits boost cut,then change gear and spool it up again and it hits 0.8bar and tails back to 0.5bar. Seems strange that 1 minute it makes enough boost to hit boost cut and the next it doesnt!
Im going to try slackening the preload off the actuator and then re-setting the boost tee from there!
Thats what i thought Karlos, i could do with a fuel pressure gauge and afr gauge and i could tweak it myself... Im pretty sure it lean atm!

 

If it's chipped why is there a boost cut?

 

A stage 1 chip limits the boost to 12psi up from the factory 7-9psi...

 

Ah, I thought it might be something like that.
I think part of the problem might be that your running a Stage 3 T3, this is going to be laggy then come in with a bang and without proper boost control you might not be able to eliminate the spike.

 

Its suprisingly not that laggy, im spooling high 2,000rpms and on full boost by 3,300-3,500... What do you mean by "proper boost control" i tried the FRST AMAL valve and it was the same scenario except i couldnt get it to hold 0.5bar, it would tail almost off to nothing. If i half throttle the car and build boost slowly i can hold the boost at 0.8bar by backing off and re-applying throttle. But if i keep a contstant throttle, ie full throttle it back right off...

I don't think its a spike so much, ive been in cars that boost spike and usually they peak and hold in a 500rpm window max, whereas i have more like a 1,000-1,500rpm window!

 

Thats not bad for a stage 3 at all, by proper boost control I mean closed loop using say an Apexi AVC-R.