Turbo won't boost above 1 bar

[200SXNICK]

... famous last words indeed. Haven't been able to do any further testing past couple of weeks as I use the car for work and been on some silly shifts. Anyway - was about to get the spanners out and whip the turbo off, but decided to do one last test on the actuator... rather than just unplugging it, I tied the wastegate arm to the aircon bracket with speaker wire. Off I went, not expecting much - came off tescos roundabout, then before I knew it I was boucing off the limiter and for a brief second approached a number I don't even want to think about on the boost gauge...

So... theres naff all wrong with the car other than the exhaust gas pushing the wastegate and actuator open. I'm pretty gutted tbh - the spring in the actuator is only rated to 0.7 bar, and thats what it hits with the boost controller turned off. However, the HKS on my old car ran 0.7 bar exactly the same, yet managed to hold back the exhaust gas with the boost controller cranked up to 1.2 bar... so a bit confused on that front. Unfortunately I haven't got the old actuator and bracket to compare lengths but I'm beginning to think I've been sent the wrong actuator altogether as I said, there are already several washers on the bracket, and the arm is screwed all the way in just to hit 0.7 bar.

So what do you guys reckon? Do I need a stiffer spring and/or more washers on the bracket, or should I just get the actuator replaced for one with a shorter arm? I'm gonna get some longer bolts and more washers just to see how much difference it makes - in the meantime, any suggestions are much appreciated thanks for all your help and patience!

[200SXNICK]

quick update - bought some longer bolts and a load of washers, which effectively shortened the actuator arm by around 6mm. it came on boost a bit quicker, but still won't make over a bar. i'm assuming this is because the spring is still too soft regardless of the rod length? anyways, i've read great things about forge customer service, so gonna give them a call tomorrow and explain the issue. otherwise i was thinking of fitting the next stiffest spring and then cutting an half an inch or so off the threaded half of the actuator arm to do away with the washers and give me adjustment.

ps. dont tell me i'm a goon for locking the wastegate shut with speaker wire - i already know that. just after so much testing and deciding the turbo was shot, i really wasn't expecting anything to happen - kinda took me by surprise!

Thanks

[200SXNICK]

another update - although nobody seems to be reading this thread anymore spoke to forge this morning and they we're as helpful as i'd been told they would be. the guy said straight away that they hadn't cut the rod to the right length before sending it out - offered to replace it / cut the rod down, but said i could go ahead and do that myself AND they are sending me the next stiffest spring FOC good times! i'll let you all know how it goes incase anyone still cares

[voodoo_melon]

I'm reading it, but you seem to be doing just fine on your own Let us know how you get on

[LED sandwich]

Do you have a Manual boost controller or electronic? Its not in back to front is it? although i guess that would cause infinte boost not under boost.

[200SXNICK]

nice one voodoo_melon, i know people are reading, just being a mard-arse

aaronledwidge, its an electronic boost controller - but the symptoms persisted even with the controller completely removed. its defo the actuator

[immy21]

Just for the record and to give you some hope, I am using a Forge Actuator using a blue spring (14psi/1bar), I had to buy a new rod for it as I bought the actuator used (straight rod is fine for S14a's with braided hoses, cheaper too). I had to trim the rod down a little but using this actuator with my £20 ball and spring manual boost controller running about 18psi everything is working in perfect harmony

[Cloudy]

First time I've seen this thread and the first thing I was going to suggest was the actuator. I bought a Forge actuator last year (brand new) and the thing was weaker than the standard item and causing me the same issue.

[200SXNICK]

immy21 - nice one for the info - they have put the yellow spring in the post today - hopefully that with my blitz ebc will hold 1.1-1.2 nicely, otherwise i'll have to order the blue one.

Cloudy - too true, I dug my oem actuator out last night, and the forge actually feels much weaker just pulling on the arm. at least i've located the issue, and found a few people who have resolved it with a stiffer spring. i'll let you all know how it goes.

[docwra]

First time I've seen this thread and the first thing I was going to suggest was the actuator. I bought a Forge actuator last year (brand new) and the thing was weaker than the standard item and causing me the same issue.

Weirdly, same here. Ive had an actuatay that was too weak but also one that actually broke its mounting, so the actuator was actualy pushing forwards on boost

[Cloudy]

Cloudy - too true, I dug my oem actuator out last night, and the forge actually feels much weaker just pulling on the arm. at least i've located the issue, and found a few people who have resolved it with a stiffer spring. i'll let you all know how it goes.

I could pull the arm with ease compared to the oem, I simply threw the Forge back in the box and replaced it with a Garrett adjustable. Think it's still sitting in the garage somewhere. At least you've found the problem though.

Weirdly, same here. Ive had an actuatay that was too weak but also one that actually broke its mounting, so the actuator was actualy pushing forwards on boost

I've not heard of one breaking the mountings before

[LED sandwich]

Ah nice work buddy, glad you found the problem. Have you tried sticking the standard one on and testing?

[200SXNICK]

"actuatay" lol

This is all making me think maybe i need the blue spring and not the yellow one... but they've already posted it so i'll just have to wait and see.

My next move was going to be putting the oem actuator back on, but can't bothered - it probably leaks anyway and the new spring should be here tomorrow

[immy21]

The standard Garrett actuator and the Forge ones have very different characteristics, you can see this easily by hooking up a footpump onto the end.

The stock Garrett will stay tightly closed then open relatively suddenly, but then is very hard to push back in and as pressure drops it pops back in relatively suddenly. Theoreticaly that means boost would come on hard but tail off high end. Yes I know stock car is very smooth and progressive but it is only a weak 5-7psi actuator.

My Forge with blue spring comes out very progressivly compared to garrett but is easy to to push back in by hand and starts coming back in progressivly. Theoretically that would mean coming on boost smoothly but hold boost better high end as the wastegate can close easier (I made that up myself btw so take that with a pich of salt). I can tell you with no MBC boost at 14psi does come in very nicely and smoothly, how a S14/a feels with stock boost. I prefer boost coming in hard so use a Bren type MBC to bring it up to 18psi to get the best of both worlds, boost comes in noticeably harder.

I don't think its fair to slate Forge for the way these actuators work, for a more aggressive on/off boost transition they offer Piston type actuators, Myself and im guessing most of above have their smoother operating diaphagram actuators. I personally really like Forge as a company, and no I dont work for them


Yellow springs 9-15psi
Blue springs 14-18psi

Both should work fine but assuming you 1a mods or higher blue would be better to give your solanoid an easier life, bear in mind if you like turning down boost the minimum you will ever get is actuator pressure so some might prefer yellow, im happy with blue

[200SXNICK]

okay, spring arrived this morning as promised. took the actuator off, measured and cut off the excess thread (around 8mm), and swapped the springs over. just in my hands the difference between the green and yellow springs is massive - feels almost double the rate... not sure if this is normal or if my green spring was knackered

anyway, the actuator was a doddle to disassamble and reassamble - apart from holding the bastard thing shut before screwing the first two bolts in once i had it back together, a quick tug on the arm confirmed it is far stiffer with the yellow spring - stiffer than the oem actuator. i fitted it back on the car and guessed the arm length - its a damn sight harder to get over the wastegate pin now

took the car out and CAREFULLY checked the base actuator pressure - unlike last time - and it hit pretty much 1 bar consistently turned the boost controller on with the gain on 90% and turned it up til it hit 1.15 - feels absolutley amazing, and it comes on boost super quick too! it only spikes a tiny bit if you slam your foot down, otherwise it holds boost nice and smooth to the redline.



i was thinking about turning the actuator down a little, but i'm assuming the spring will sag a bit once its bedded in? also i'm really happy with it as it is - feels faster than my old 1a car

Thanks a lot everyone for all your help, looks like this one is solved! Good times

[voodoo_melon]

Good to hear you got it sorted

i was thinking about turning the actuator down a little

Don't be

[CrysAk]

great posting ... I'm currently looking for a new actuator, so think forge is the way to go ^^