61 replies to this topic

[Nev]

Please ignore what I said further up, I think I may well be wrong and SizTenboots is probably right. I got confused as on my car with the external wastegate I provide boost to the opposite side of the diaphragm, so I think the effect is the opposite of the OEM actuator.

[Dave E]

Sorry if this a stupid thought but could the pre loading of the actuator be a contributing factor. We pre load the (cosworth?) actuator to try and obtain the desired boost level but isn't this a bodge to try to add some adjustability to non adjustable part. By doing this wouldn't we be making the spring shorter thus reducing it operational length and wouldn't this in turn effect how it reacts so would fitting an actuator with the exact spring rate improve matters? Again sorry if this is way off but just trying to get my head around it. My head hurts now so I'm going to bed

Edited by Dave E, 20 June 2014 - 05:08 AM.

[P11 COV]

Sorry if this a stupid thought but could the pre loading of the actuator be a contributing factor.  

 

with no preload my car would hardly boost at all.

[Duncan VXR]

No overly read the last few posts so sorry if it duplicates

 

In basic terms and no ecu control of boost the turbo would allow the boost to build to the load of the actiuator at which point it vents directly into the exhaust.

 

If there is too little or wastegate not shutting fully you will be driving what feels like a n/a (slow Vx ) with the preload set correctly and the wastegate penny opening and closing freely it will drive and boost fine but will not be overly fast - if you have a boost guage you can see the level build and hold a lower reading (7psi iirc)

 

The ECU using the boost solinoid applies more pressure to the wastegate stopping it opening at the preload value (7psi for example) which is taken from the compressor housing and will have a requested boost target (12psi for example). At this level it will then vent excess boost opening / shutting wastegate.

 

The ECU will then constantly adjust this based on actual boost v's target. Venting the boost through the solinoid (into intake of turbo housing) when no more boost required. It also works with the recirc for when closing the throttle (changing gear) if dumps the compressed air back inot the intake.

 

If there is too much preload and or the wastegate penny does not have enough travel to open you will overboost for obvious reasons - this can be seen on a boost guage if fitted. The solinoid controlled by the ECU will try to vent all the boost to try and reduce through wategate but the basic mech setup of actuator / wategate are still boss when not operating correctly

 

The Z20LET is like most other older turbo cars and same rules apply

 

The newer stuff gets a lot more fancy using the recir to also regulate boost with the wastegate to get better response and ad to the fun when it plays up

 

Hope this helps a bit in basic terms, typing on phone is a mission lol

 

Run with solinoid unplugged - does it perform ok?

Check wastegate movement (un do actuator bolts to allow the threaded bar to move freely)

Check vac setup for ANY leaks inc vac storage box

Check for any boost leaks

Set preload if all ok

Poss replace recirc if required

 

Beyond this some datalogging would be really usefull to see what the ECU is doing during the issue

 

DG

[slindborg]

Would it be at all plausable to use the ECU control line that runs the boost solenoid to directly control an electronic actuator?

[Duncan VXR]

I have no expriance of electronic actuators on the hot side. I have only messed about with the recirc electronic actuators on the tfsi lump tbh

 

Guess the signal from ECU would need reviewing to see what it is and how if functions. Then see what electronic actuator is suitable to mounting to turbo and what signal that would like to function correctly

 

I think its one for you to go and play with slindborg  but no reason for it not to work, in fact be interesting to see how it performed

 

DG

Edited by Duncan VXR, 20 June 2014 - 11:50 AM.

[siztenboots]

back when I worked at Staefa Control System, we used a 0-10v and a transducer to 0-24vac and phase cut for modulating end devices (valves & dampers).

 

maybe there is something in the moog catalog

[slindborg]

could use a VGT actuator with suitable rod etc to make it fit the K04.

 

It can join the queue of other electronics I've yet to get round to

[Dave E]

@ Paul, sorry worded it wrong what I was trying get at was are we pre loading beyond the normal working range of the actuator sping to get the desired boost level Thanks everyone else, I'm slowly getting to grips with this and Stuart I probably won't be holding my breath for you

[siztenboots]

if the remaining actuator stroke length was too short to allow the w/g to open wide enough , then you would see boost creep at higher rpm  , I think most of us see 18psi held and tailing off as normal.

 

[P11 COV]

if the remaining actuator stroke length was too short to allow the w/g to open wide enough , then you would see boost creep at higher rpm  , I think most of us see 18psi held and tailing off as normal.

 

 

I seem to be getting spot on 20 at the moment - too much?

[Dave E]

I was seeing 22psi (the most it's ever done) over boost at Croft then falling to around 15psi. At lift off I was only seeing 15hg when usually it would be 20. Using my new vacuum tester I checked all the pipes without finding anything so the absolute last thing to check was the vacuum canister and found this



Think I might of found my problem

Edited by Dave E, 06 July 2014 - 04:37 AM.

[VXT Tim]

Impressively melted Dave Seen cracked ones before but not melted

[Dave E]

What the he'll are you doing up Tim, if I weren't working I'd be sparco or drunk or probably both At Snetterton my exhaust split at the flexi but obviously I carried on. Not a good idea, melted the gear cables, vac pipe and canister and the inside of my near side rear tyre

Edited by Dave E, 06 July 2014 - 04:57 AM.

[Goosenka]

Sure I can see eyes and a face in that

[VXT Tim]

Went to bed at 9 so woke up early, just re woke up though I can goose, bottom right corner

[Goosenka]

[VXT Tim]

[Ormes]

Blimey that's impressive!

[hairy]

Jeez - amazed you got any boost at all with that!