Actuator/ wastegate pressure

[225tt]

Hi all,

I have a audi tt 225 BAM (53). Came here as I think this forum is a lot more active and has more people who like to play about with the engines!

So pretty sure our engines are identical/ near Enough so it should correspond.

Basically with my n75 electronically unplugged I would see my boost be around 0.4 bar I think it was ( via boost gauge) this would hold until 5000rpm at which point it would sharply go back to 0!?

I assumed this could be the turbo actuator. When n75 electronically plugged in my boost was generally bang on (.9 bar) but especially in say 2nd and at times 3rd I wouldn't hit the .9 and would be more like .7 or so.

Now I fitted a pattern part actuator which seems identical on looks at least. Car now always hits .9 in second too. Issue is with n75 unplugged electronically I still get maybe .4 bar or so then it falls off if anything sooner?

Final note. Some may ask why I bothered changing the actustor as the car was mainly fine. Reason was I took the car for a revo remap and it wouldn't make over 1.0bar boost. It was thought it was the turbo but I hear no noises that are dodgy and car is just at 80k miles. Also pinned mainly in the noise at which point I had an open cone filter which sounds whiney and mapper hadn't heard on before suprisingly on a tt. Either way map wasn't put on but stock the csr made 224 bhp on pretty realistic rollers from what I see.

So all in, is it normal my boost drops out higher in the revs first of all?

 

[225tt]

Also should add since looking up the actuator issue I found lots of posts from this forum and including badger5. I wish I had gone there initially as it's closer than where I went to me and seems to be a lot of expertise with specifically these engines so bill if you see this I would be interested in your input too and from a mappers point of view what your thoughts would be. ( I unfortunately didn't realise you existed at the time ( no offence!) and were in Gloucester area hence not using you back then

Many thanks

 

[W11TTX]

If I'm right with the n75 unplugged you only get actuator boost which is low as the n75 is the boost controller so unplugging it is like getting a manual boost controller and winding it down .

 

[225tt]

If I'm right with the n75 unplugged you only get actuator boost which is low as the n75 is the boost controller so unplugging it is like getting a manual boost controller and winding it down .

This is pretty much my understanding as well. I was expecting the low figure as the actuator now sees all the pressure of the system as the n75 isn't diverting some of it away from it to prevent it opening the wastegate and hence increasing boost.

My main issue is surely it should hold the 0.4 bar or whatever figure it was through the rev range? Does anyone know what there's does? And if it shouldn't do this what could be causing it!?

Thank you

 

[grahams81]

My main issue is surely it should hold the 0.4 bar or whatever figure it was through the rev range? Does anyone know what there's does? And if it shouldn't do this what could be causing it!?

Thank you

If it's not holding the boost pressure through the rev range then you may have a leak in the boost pipes after the turbo, have it smoke checked.
Bill's @ Badger5 your man for this... and pretty much everything else i know he's a busy man though so contact him asap if you want a real expert on the car.
Get him to map it as well as his maps have an excellent reputation, he won't try and map your car then send you away with a "can't map your car cos there's a problem somewhere" he'll at least diagnose the fault.

....or if you wan't to try and sort it your self - maybe the wastegate is being blown open / flowing too much through..... how much preload did you apply to the rod of the actuator ?? if you simply closed the wastegate by hand then locked the nuts you'll need to reset it.

The wastegate has to be preloaded enough to hold the wastegate shut but as a result of adding preload you loose travel of the rod - i.e the more preload you add the angle of the wastegate flap won't be open as much, this is normally not an issue unless you add crazy amounts of preload.... higher boost will be the result of more preload.
Too much preload can induce boost creep due to the fact the wastegate won't flow adequate amounts due to the reduced travel.

It sounds like yours is the other way round so after checking for leaks i would leave the n75 unplugged and add preload to the actuator rod until you see 0.5-0.6 bar right through the rev range.

Good luck.

 

[ibizacupra]

okies..
normal in my experience of these is 5psi actuator, which on occasions rises to 8psi up top as they can creep a little as std. (small wastegate hole borderline big enough as std... and can be horrendous boost creep on Cn copy hotsides which are even smaller wastegate holes)

That said, this is'nt whats happening with yours
Going to zerois'nt normal...

logging may confirm if this is ecu intervention however opening DV as its unhappy about something.. which would render you with 0

leaks are The Most prevalent issues on these cars, so I always start there... and 90% of the time find leaks which need fixing before progressing to then next step.

another possible, is very weak wastegate which will blow open as its got tired..
if you need it looking at my contact details are in my siggy.
Location, Stonehouse.

cheers

 

[225tt]

If it's not holding the boost pressure through the rev range then you may have a leak in the boost pipes after the turbo, have it smoke checked.
Bill's @ Badger5 your man for this... and pretty much everything else i know he's a busy man though so contact him asap if you want a real expert on the car.
Get him to map it as well as his maps have an excellent reputation, he won't try and map your car then send you away with a "can't map your car cos there's a problem somewhere" he'll at least diagnose the fault.

....or if you wan't to try and sort it your self - maybe the wastegate is being blown open / flowing too much through..... how much preload did you apply to the rod of the actuator ?? if you simply closed the wastegate by hand then locked the nuts you'll need to reset it.

The wastegate has to be preloaded enough to hold the wastegate shut but as a result of adding preload you loose travel of the rod - i.e the more preload you add the angle of the wastegate flap won't be open as much, this is normally not an issue unless you add crazy amounts of preload.... higher boost will be the result of more preload.
Too much preload can induce boost creep due to the fact the wastegate won't flow adequate amounts due to the reduced travel.

It sounds like yours is the other way round so after checking for leaks i would leave the n75 unplugged and add preload to the actuator rod until you see 0.5-0.6 bar right through the rev range.

Good luck.

Thanks very informative. I did add preload. Approx 17 mm from the end of the furthest nut from the actuator to the end of the rod which I believe is correct.

I thought of boost leaks but then thought why can I hold boost when n75 is all connected!? I don't quite understand the system so maybe this is possible. Either way I'm sure there are probably a few small ones at very best. Could maybe figure why with a tested remap car found it harder to boost higher.

 

[225tt]

okies..
normal in my experience of these is 5psi actuator, which on occasions rises to 8psi up top as they can creep a little as std. (small wastegate hole borderline big enough as std... and can be horrendous boost creep on Cn copy hotsides which are even smaller wastegate holes)

That said, this is'nt whats happening with yours
Going to zerois'nt normal...

logging may confirm if this is ecu intervention however opening DV as its unhappy about something.. which would render you with 0

leaks are The Most prevalent issues on these cars, so I always start there... and 90% of the time find leaks which need fixing before progressing to then next step.

another possible, is very weak wastegate which will blow open as its got tired..
if you need it looking at my contact details are in my siggy.
Location, Stonehouse.

cheers

Thanks bill! I do have vcds and have done logging. Not sure exactly what I. Should be looking at times. My air flow looked good funnily enough from the logs I did do so it's making power ok at stock you would take from that. Approx 185g/s which I'm sure is pretty good for stock.

Leaks I agree with, I'm really busy maybe until after Xmas but be sure I will be wanting you to do a smoke test as I see toy do those, even if it's not causing this issue it's a good thing to check.

My initial thinking was weak wastegate. I have change it for a pattern part as I mentioned so hoped if it was maybe this would improve things. N75 disconnected is no real difference. but connected my boost seems stronger and quicker to boost up compared to the old one. Especially in 2nd gear where before I wouldn't even quite get to 0.9bar.

Really strange. Anything obvious I could see from logs? I have a few old ones with the old wastegate that I could post up, not sure if correct parameters but some useful values I hope.

Thanks again bill for your input, as I said certainly want to bring the car to you if I can get it mapped but also smoke test if it seems the only likely cause of this and maybe the lower boost than requested achieved at my last try...

Thanks again. Really appreciated, wrote the same thing on the tt forum pretty much and got 0 replies lol! (Great forum too but not so much input I find)

 

[ibizacupra]

TT forum - enough said

log blocks 003,115,118

will show load, requested vs actual vs n75 duty cycle.... see if ecu's turning off n75... from some intervention etc

 

[225tt]

TT forum - enough said

log blocks 003,115,118

will show load, requested vs actual vs n75 duty cycle.... see if ecu's turning off n75... from some intervention etc

Here is a log i did in 3rd gear a couple of months ago, this was a few weeks after the remap which failed (Emphasis again that the car is indeed still on the stock map now as i chose not to pay for a map that i was told could finish the turbo quicker but was also not making required boost as it wouldnt go over 1.0bar, believe out of interest is made 240BHP.

I think this log may have what you are asking for, i will check some of my ones i did last week to see they look similar. Also to note is this is on the OEM actuator and before i replaced it (not sure if this has even made a difference, in terms of getting remap requested boost if this was the issue then maybe it has but of course that cant be found out until i try for another map.)


finally one thing i should add, i belive this oly logged about 1 point a second which is abit slow for my liking, dont think i can improve it though and it makes the graph look a litte weird possibly.

Thanks all

 

[225tt]

cant post images until i have 15 posts... what a useless rule, now i have to basically spam other sections so i can post a pic!?

 

[ibizacupra]

more data points then choose taller gear or log less channels at same time

 

[225tt]

more data points then choose taller gear or log less channels at same time

Would do 4th but difficult to find a good place to do it! Not sure if i can make it log quicker any other way though? and i find just 2 channels at a time doesnt usually give enough info, prety sure the never "VCDS" version lets you choose actual individual blocks but the old one sticks you with all the data of a particular measuring block. ANyway below hopefully is my graph i mentioned above!:

[/URL]

 

[225tt]

and another log vs time, this was done maybe a week or two ago.

[

In the first throttle opening N75 looks pretty smooth? but later it seems not as smooth but also as i have highlighted drops out to 0, maybe this is a logging error or something or is this some sort of intervention maybe? Any ideas anyone!? My boost one day does seem strong then sometimes seems a little under par, maybe the N75 is on its way out or something?

Thanks for any input

 

[ibizacupra]

n75 switching off is an intervention I believe in your case.
cause of it however not obvious from your logs

 

[225tt]

n75 switching off is an intervention I believe in your case.
cause of it however not obvious from your logs

Thanks bill. Anything you would recommend to log from here? Possibly egts and knock counts or something?

Funnily enough my EGT sensor was faulty when I bought the car so it's had a second hand unit put in by myself. Before that the car was going into limp. Currently no fault codes though and this never limps, never even felt anything different in that dip of n75 log infact but could show why a higher turbo pressure wasn't made maybe.

And again sorry for being a pain. I can imagine it's really difficult to help with problems when you don't have the car Infornt of you but I'm very curious and would like to try and solve this and then look for a smoke test and map after, or maybe the car has just had it and has no chance of ever being sorted as maybe the turbo is just on its way out or something ( no obvious signs as far as I'm aware though) in which case I think I would keep the car abit and sell it on later as stock it make a it's claimed figures still and drives well.

Thanks

 

[225tt]

Ok some pretty good news i think...

First off, i changed the actuator a week or two ago as i mentioned and saw maybe a smal difference in boost etc but not really. What i didnt add as i thought i had buggered everything up was that as i was screwing in the top mount screw for the actuator the thread suddenly stripped on the turbo part (not the screw). Now i didnt say anything as i thought with the space restrictions etc the only answer was turbo out which i wasnt prepared to do to be honest. Anyway left the actuator mounted on only on the bottom screw, i was not happy about this at all and i realised at the time it was less than an ideal but it seemed quite sturdy for the meantime, but on pulling on the actuator rod it did seem to bend a tiny bit.

Anyway long story short(ish). I had cud down the top bolt to put it back in without removing the oil feed banjo. Now this made me think there must be a few more threads left so i was going to attempt to tkae the oil feed off do it properly. It just so happened i checked through some photos of the old actuator on the car and i noticed that the screw mounts infact are not blind holes!!!! I was so happy seeing this. Anyway yesterday i fitted a rod section and nutted it tight both sides and re adjusted the actuator to what i believe is the right setting.

GOOD NEWS! The car now seems transformed. I would say 30-70 or something its probably not much different in true performance wise but the pickup of boost now and torque low down is incredible! makes the car feel so much quicker even though in reality its probably only a little. Boost now peaks at 0.9 touching 1.0 through the rev range everytime!

So my theory is my actuator left bodged was as i expected to be honest bending a little and so the wastegate was effectively opening somewhat anyway. So all in im happy, only a question or too left now...

I set the wastegate preload at approx 17-18mm from the end of the outside nut to the end of the rod. From memory i think i shut the wastgate arm then turned the nut maybe 1 or 2 complete turns at most, does this seem ok/correct?

secondly n75 electronically unplugged seems a little better, 0.4 bar but drops to 0 at 5k. Maybe the wastegate needs to be tightened more and the above of setup is not tight enough anyway?

Thridly, n75 plugged back in, boost gets up quicker to 0.9-1.0 bar according to boost gauge, never overshoots at all, holds to just before revline without creeping. Just short of redline it drops a tiny amount, i believe this is the standard map to do this, strangely i thought it was supposed to do this but i have never seen it before, i think it is because i never quite made high enough boost to begin with.

Lastly, this may have cause my 1.0Bar max boost when i went for a remap, and so possibly can take a remap and hit the required boost now?

Thanks all, all in im happy so far anyway, car seems a lot more lively!

 

[225tt]

Quick update.

Logged with the N75 unplugged again. First thing i noticed is that i get no dash lights but i do get a fault code coming up saying that the N75 is open circuit. Checked my logs and after around 4500-5000 rpm my throttle although being floored by me is being held at around 30%. I assume this is the ECU trying to protect itself (not sure why in this configuration) from any boost issues.

Logged with all plugged in and actuator all nicely set up, 2 turns preload (believe correct or close to correct!?) All looks good, requested boost vs actual boost pretty much follow each other now. Did notie when logging EGT that in can get to 920c after doing a couple of through the gear short runs, is this acceptable?

Also as the turbo was possibly in question and i was still worried that maybe the actuator was giving me a false sense of the turbo being ok i took off the actuator line form the N75. Obviousy was very steady with the throttle, boost FLEW to 1.0bar in 4th gear i believe it was and i left it at that, this gives me confidence that i can easily make remap boost (in terms of the turbo)? Car infact also limpped after this, i later tried to get to maybe 1.1 bar but it wouldnt boost over 0.5 even under full throttle. I think the ECU detected a slight oveboost from the previous run and probably cut the throttle again (Couldnt open the wastegate for obvious reasons). Pluged the line back in to the actuator and it still only made 0.5 ish for the next couple of pulls, then suddenly it all clicked and was fine again! So must have been the ECU learning whta was going on!