Boost Valve has little effect

[TenaciousC]

Hi All,

Have fitted a boost valve (originally purchased for a Nissan200SX) between the Boost control solenoid and the turbo actuator.

Spiel on valve

It is of the spring/ball-bearing type with an ajustable screw which stops pressure reaching the turbo wastegate actuator thus preventing it opening thus increasing boost.

Results of fitting this were not quite as I imagined. Boost levels have not radically changed.
Needle is going into the white area, but not all the way across. I have been progressively closing the valve but no obvious improvement.

I'm wondering if the wastegate actuator is broken. I can move the arm manually - whilst there is resistance - I would have expected it to be stiffer. Is this normal?

Cheers

Chris

[850 t5 vs 600cc]

how much boost are you getting at the minute?

[TenaciousC]

I don't have a proper gauge yet so can can only say (using the standard dashboard gauge) in general the needle goes to the middle of the white area and a little further at high rpm if you really go for it.

C

[BigV]

Have you completely disconnected the factory fitted BCS from all the air pipes? (but still leave it plugged in to the power cord)

My understanding is that the manual boost controller should completely replace the factory fitted boost control solenoid......, certainly that is how I set them up on my old 850 T5.

I mean other problems could be numerous to be honest.... air/boost leaks are most common, but dodgy ignition or fuel injectors etc etc could cause issues.

[TenaciousC]

No the BCS is still connected. To my mind the valve should augment the control effects of the BCS. The less pressure at the actuator the more boost you should get. If you completely disconnected the hose, you would get the most boost (although un controlled). This is why I think the actuator may not working correctly, i.e. it is allowing waste gate to open too easily.

However I suppose my question is still "should I be able to move the actuator control arm with gentle force"? On my 200sx I can't do this - hence my concern.

Cheers

C

[AlanG]

First thing I did on buying my T5 was adjust out any wear in the actuator mechanism. You sound pretty clued up,have you already done this? Secondly,after I had mine re-mapped I wanted a little bit extra so fitted an R-Spec mbc and fitted it as per their instruction (BCS removed but still electrically connected). It was fully adjusted but didn't seem to have a huge influence. Having spoken to Hamish at HLM,I plumbed the BCS back in and backed the MBC off,then back up in 1/4 turn increments until the dash guage just off scale. Done 1000 miles since and no problems. Suppose my point is that your controller is fitted correctly and as you've been working in that area,you'll have checked for any split vac pipes etc. I'm assuming your mbc is a universal one?

[BigV]

I haven't heard of running both the BCS and an MBC at the same time.... how does one plumb it in properly?????

I have an MBC ready to fit but I was just planning on removing the BCS and leaving it electronically connected to avoid warning lights etc.

[AlanG]

That's the way to do it buddy. You'll find the vac pipes at the BCS are colour coded. Split the yellow one (BCS to actuator) and install it there. Basically means that your ecu is still in ultimate control but allows for an increase in boost. Hamish at HLM told me this so anyone not in agreement,take it up with him

[BigV]

That's the way to do it buddy. You'll find the vac pipes at the BCS are colour coded. Split the yellow one (BCS to actuator) and install it there. Basically means that your ecu is still in ultimate control but allows for an increase in boost. Hamish at HLM told me this so anyone not in agreement,take it up with him

What PSI have you got it set to with the rica map.......... I know mine is hitting about 16.5 with the rica, but it is the quick launch of the MBC I am really after, so im thinking of fitting it and setting it for about 14.5 to 15 to be safe.

[AlanG]

This is where I get criticised as I don't have an accurate guageJust tickled the mbc till the dash guage just off the scale. Goes like the wind and 30+mpg.

[p fandango]

Basically means that your ecu is still in ultimate control but allows for an increase in boost

the ECU will only have any form of control if the MBC is set lower than the standard boost level. Setting it like that will give a better boost pick-up but won't increase the boost any

it does make installation alot easier tho

[AlanG]

Can't argue my friend as I don't know enough about it. Just went on what Hamish told me. Noticeable power increase with the mbc though.

[TenaciousC]

First thing I did on buying my T5 was adjust out any wear in the actuator mechanism.

Can I ask how this is done? Is there a howto somewhere?

Cheers

C

PS. Just ordered boost gauge ;-)

[AlanG]

Remove the heatshield (I'm sure there is a thread somewhere on here that gives a how to,try a search) undo the locknut on the actuator rod and remove the r-clip.If I'm correct,the popular method is to shorten the rod by 8 HALF-turns and re-assemble. Certainly noticed a difference with mine and I'm sure if I'm wrong someone will correct me HTH.

[TenaciousC]

Hi,

10(ish) turns on the actuator rod and winding MBC in has helped, and now needle is getting to end of the white. Will fit boost gauge before attempting anything further. Thanks for the advice.

C

[t5lover]

mine runs on standard ecu and am using bcs and mbc and the actuator i turned it about 2-3 times and she is boosting about 14.5-6 psi and she is wicked,,

[AlanG]

Hi,

10(ish) turns on the actuator rod and winding MBC in has helped, and now needle is getting to end of the white. Will fit boost gauge before attempting anything further. Thanks for the advice.

C

Glad to be of help buddy. Was that 10 half-turns? Mine is a couple of mm beyond the scale and will probably need to replace front tyres every couple o weeks

[TenaciousC]

Glad to be of help buddy. Was that 10 half-turns?

10 Full - I think! Am about 5mm before the end of the thread on the arm. Perhaps my actautor is knackered. Anyway boost has improved and no fuel cut so I'm happy (for now) ;-)

C

[AlanG]

That's a drastic adjustment! No expert but sounds like a cooked actuator. I'm sure someone better qualified will have some advice.

[t5lover]

That's a drastic adjustment! No expert but sounds like a cooked actuator. I'm sure someone better qualified will have some advice.

i would say the same mate its fit for the bin mate lol,,,,