Problem with overboost on single turbo :(

Well shes all back together and seems to be running well, just need the map sorted now!

I have noticed however that when @ WOT it seems to be overboosting considerably! The other night it seemed to be holding at 1.15 bar according to the logs, however i have just taken her out and it just seems to keep climing, at one point i saw 1.3bar. Obviously i let off straight away! Its not an intermitent fault either so what can it be?

Boost controller is also turned off and is set in the wastegate position.

Help!

EDIT: Just realised the stock map sensor can only read to 1.15bar so thats probably why it looked like it was holding boost .

Well shes all back together and seems to be running well, just need the map sorted now!

 

I have noticed however that when @ WOT it seems to be overboosting considerably! The other night it seemed to be holding at 1.15 bar according to the logs, however i have just taken her out and it just seems to keep climing, at one point i saw 1.3bar. Obviously i let off straight away! Its not an intermitent fault either so what can it be?

 

Boost controller is also turned off and is set in the wastegate position.

 

Help!

 

EDIT: Just realised the stock map sensor can only read to 1.15bar so thats probably why it looked like it was holding boost .

wastegate mate if you have the boost controller turned off, maybe take your boost controller out of the equation and connect up direct to the wastegate and you should boost to whatever the spring tension in the wastegate is, when i first went single my manifold came with a wastegate which proved to be faulty i also upped the size of the exhaust tube to the wastegate as it was not allowing enough flow

Going to try it without the boost controller in a sec. However i find it hard to think its the Wastegate as its a HKS one i got from Gaz1, which was workin fine when he took it off.

One thing i did wonder was if there was a split in the feed line (the one to the top of the WG) would this cause it to overboost? Surely it would make it just run a the WG spring pressure though . Only reason i wonder is because it is currently just some cr*ppy vaccum hose that i havnt replaced with decent stuff yet.

Just took her out after connecting the lines from the boost controller in and out ports together, thus removing the controller from the loop...and it went mental, gradual increase as normal then hit 1.5bar before i could let off! And i was taking it easy, trust me!

Confused

Which WG is it?

Which manifold is it?

Just checking its not another dodgy XSpower one with the wastegate hole that is too small.

What spring does the wastegate have fitted?

The HKS wastegates are available with various different spring ratings. The spring will determine what the peak boost is, it could just have a higher rated spring in so is not opening until later.

the manifold he is using (i think was the xs power but the wastegate port was opened up as it caused me the same problem, but was sorted after) the spring i believe is only a 1bar (i think) but the pipes coming of the wastegate would cause you overboost if they have a split, i just encountered this problem too:rolleyes:

Its gaz's old manifold and HKS wastegate, it was all working fine when it came off. Dont know what spring it has but gaz said he had his controller set for 1bar and 1.4bar so the spring must be 1bar or less.

Will change the lines asap just incase there is a pin hole or something.

your using the same gt40/88 as i did i believe, so i would bet its the pipes, as i never had overboost after the port on the manifold was sorted;)

your using the same gt40/88 as i did i believe, so i would bet its the pipes, as i never had overboost after the port on the manifold was sorted;)

Yep same size tubby so hopefully it just the pipe.

Right, i have tried sourcing the boost signal from the intake plenum side, exactly where the boost controller reading comes from so i know there are no leaks and the WG should open at the correct time. I have left the top WG hole as vent to atmosphere, and blocked the original feed from the turbo.

She still overboosts . In higher gears it seems to hold a short amount of time at 0.8bar so i assume thats the spring fitted...however as soon as revs increase it just continues to increase and overboost. I can hear the WG opening approx 0.8bar.

Any ideas? Ryan is coming next friday to map it and i really need this sorted or i will have to cancel . I cant see how it can be the wastegate as gaz1 had it fitted to his and as far i know it was working fine when removed.

Any ideas? Ryan is coming next friday to map it and i really need this sorted or i will have to cancel

Why are you doing WOT pulls before its mapped

Why are you doing WOT pulls before its mapped

Because i was going to map it myself but thought better about it, decided to let ryan do it. I started doing the fuel map myself, timing is safely retarded mate...im not that stupid

Right, i have tried sourcing the boost signal from the intake plenum side, exactly where the boost controller reading comes from so i know there are no leaks and the WG should open at the correct time. I have left the top WG hole as vent to atmosphere, and blocked the original feed from the turbo.

 

She still overboosts . In higher gears it seems to hold a short amount of time at 0.8bar so i assume thats the spring fitted...however as soon as revs increase it just continues to increase and overboost. I can hear the WG opening approx 0.8bar.

 

Any ideas? Ryan is coming next friday to map it and i really need this sorted or i will have to cancel . I cant see how it can be the wastegate as gaz1 had it fitted to his and as far i know it was working fine when removed.

simple either your wastegate is to small or the tube off the manifold that feeds it is to small

simple either your wastegate is to small or the tube off the manifold that feeds it is to small

I completely agree thats what it seems like...but the manifold and WG (50mm HKS) are what came off Gaz1's car. The post size has apparently been increased and he didnt have any problems with overboost after that. He was running the same size tubby too . woe is me, i dont want to have to pull the whole thing off again!

What could cause the WG to only partially open? just a theory.

Im lost on this one as it was a working setup before fitted to my car.

are you sure you have it plumbed up right, which port are you using on the wastegate, if its all off a running car there cant be anything wrong with the manifold

Sean,Re-plumb it to the compressor fitting,(that ref should always be pre throttle plate) check the line going to the wg side port by pressurising it from the connection point at the compressor fitting.

Paul, at the moment for test purposes i have the top port vented to atmosphere and the side port to reference boost signal.

b'have, i realise the reference signal should normally be before the throttle plate however i temporarily had it fed from after the plate just to see if there was a problem with the feed. I cant see how the signal line being after the throttle plate would effect the WG opening apart from maybe a slight delay.

I originally had the feed from an intercooler pipe literally straight after the compressor housing as i didnt like the idea of tapping into my nice shiny housing! I could do with pressure testing the whole system, however i dont have a compressor so its kinda hard!

i will confirm that the wastegate and manifold was working fine when they came off with no overboosting

Well i tried changing the feed line again and its still not working properly . Thinking about pulling the WG off later and having a poke around. Anyone got any other ideas...really starting to get me down this!

Right, after much deliberation i decided to take the WG off today. Now, i need a bit of advice from those that KNOW first hand.

In order to test the opening of the gate i have connected the side port to a foot pump, the top feed has been left open. I believe it has either a 0.8 or 1bar spring. This is all done with the WG off the car. When pumping with the foot pump it seems the gate only opens approx 50% @ 1-1.2 bar, and isnt fully open until 2bar ish. The gate then slowly closes when i stop pumping and the pressure drops. Now to me this suggest a leak within the wastegate diaphram, however some more educated views are most welcome.

HELP HELP HELP!!!

Right, after much deliberation i decided to take the WG off today. Now, i need a bit of advice from those that KNOW first hand.

 

In order to test the opening of the gate i have connected the side port to a foot pump, the top feed has been left open. I believe it has either a 0.8 or 1bar spring. This is all done with the WG off the car. When pumping with the foot pump it seems the gate only opens approx 50% @ 1-1.2 bar, and isnt fully open until 2bar ish. The gate then slowly closes when i stop pumping and the pressure drops. Now to me this suggest a leak within the wastegate diaphram, however some more educated views are most welcome.

 

HELP HELP HELP!!!

your test is not entirely accurate as dont forget as the wastegate opens it has high velocity air forcing it open as well, so i would say doing it with the foot pump is not a true replication of whats going on when you are on boost, i had issues with my wastegate when i went single (it turned out to be worn badly on the stem and was passing) so i bought a cheap hks copy to proove my point i think it cost around £80 from the states and was delivered within a week, it prooved my wastegate was at fault and 3 years later is still on the car working fine, the turbocharger pressure control is a basic circuit, if you know your manifold was up to the task before, it leaves you with either the wastegate or the way its plumbed up there is nothing else in the circuit that will control boost, if you have bypassed the boost controller and have the impulse line to the wastegate plumbed into the pressure housing on the turbo you are left with one thing, the wastegate

your test is not entirely accurate as dont forget as the wastegate opens it has high velocity air forcing it open as well, so i would say doing it with the foot pump is not a true replication of whats going on when you are on boost, i had issues with my wastegate when i went single (it turned out to be worn badly on the stem and was passing) so i bought a cheap hks copy to proove my point i think it cost around £80 from the states and was delivered within a week, it prooved my wastegate was at fault and 3 years later is still on the car working fine, the turbocharger pressure control is a basic circuit, if you know your manifold was up to the task before, it leaves you with either the wastegate or the way its plumbed up there is nothing else in the circuit that will control boost, if you have bypassed the boost controller and have the impulse line to the wastegate plumbed into the pressure housing on the turbo you are left with one thing, the wastegate

I completely understand paul, i had that view too as i know i could here the gate open much earlier than 2 bar (when fitted i mean!).

In you experience if i was to leave the top feed vented then it should just run off the spring pressure, right? Also, there is a bolt in the middle of the top of the wastegate which is fully done up. It was like this when i got it so i assumed it should be like this.

I did have an xs power one, but i sold it a few weeks ago . Didnt plan on having any issues with a nearly new, genuine HKS! Will have to see if theres anyone i can borrow one off as im barasic at the mo

Sean you will need a high pressure line to test the gate, we have a fitting we can attach to apply different pressure ranges so we can preload the spring or test which spring rate is in the gate. works like this..

Problem is, if the valve is sticking when hot this test wont show it, you could try stripping the gate down and polishing and lubing the shaft up to make sure its not sticking, and also make sure the valve isnt sticking in the lower seat. Aslo try a good hardline such as fuel hose incase (if your using it) the Silicon line is ballooning when it heats up.