Boost oscillation- on external gate!
 

I have a TIAL external wastegate with a 15psi spring inside it.

The gate signal is plugged directly into my compressor housing port.

My boost is oscillating between 6psi and 18psi.

See attached plot:

Attachment 241518

What do you think would cause this?

Every car Ive tuned or ridden in with a TiAL had rock solid boost and no issues.
I would start checking your vacuum source/routing.

It sounds (from the many times you keep finding new issues) like you really should take more time with and put more effort into routing everything properly and without leaks.

Tell us about how you're using a large hose, so large that it will barely grip the barbs.

Are you using a boost controller? (I had this problem)

Are you sure the turbo inlet and outlet are sealed-up tight?

Are all couplers right?

Did you install the spring or open it up?

Are the plugs tight in the gate, and do you have one port open on the top of the gate?

see ^

are you positive the spring in there is for 15psi?
does the gate go to atmo or routed back in?

This was actually a problem at first- the nice tight fuel injector hose got brittle and started to leak. Put a fresh silicone hose on and still had the same issue though.

No, directly routed with 1 hose compressor to gate.

Everything should be but I will check it again.

Everything should be but I will check it again.


Yes I installed the spring and yes I opened it up.

Can't be more than 15psi unless you stack springs. See here. (pdf)

http://www.tialmedia.com/documents/w3_tial_38_sp.pdf

post a screenshot of the log showing the oscilation

Are you absolutely certain you did not pinch the diaphragm, by starting the bolts then checking visually for clearance?

Are you certain the spring is seated in the grooves?

've heard of people twisting the spring (it grips at the housing) and causing problems like this. You should take it apart and inspect the diaphragm.

That is what I am thinking too. There's not much else to go wrong.

Unfortunately I think I will have to take off my turbo to do so. sigh

^^ what he said. you're showing us power oscillation which could be caused by things other than boost oscillation.

needs more BOOST log.


http://www.boostedmiata.com/gallery2/d/4830-1/lean.JPG

http://www.boostedmiata.com/gallery2/d/4839-1/noise.jpg

http://www.boostedmiata.com/gallery2...e_olderguy.jpg

OK Here's a log when it was doing it's thing.

hydra have an over boost? are you setup for spark cut only? I'd look into that...
the first dyno i posted was a car trying to run 14psi with a 12psi overboost.

won't boost cut stop him from making a complete pull all the way past redline?

or are we talking about some sort of "soft cut" that will dumb down the boost without completely cock blocking him?

not if you keep on throttle. try it on your MS...stay on it, youll just bounce on/off limiter.

Yes overboost was set to 20psi and it hard cuts fuel for 1/4 of a second. It's very noticeable.

That first dyno chart of yours really does look similar though.

My new license plate will be:

VOMTCMT

I just went for a drive and my girlfriend datalogged. She was not impressed by my car's unconventional power delivery. Boosted part of log is attached. I am not hitting boost cut.

So it is probably a stupid mechanical issue.

Update.

I figured out the problem.

Attachment 241513

What's wrong with the circled item in this picture? Those of you who have worked with an external gate before should be able to figure it out.

This really is worthy of much facepalm. If I had a sense of shame I would not post this. At least I was not the only one who missed this though. Yesterday all of http://www.amstuning.com/ and element tuning were staring at the thing and did not notice despite them installing hundreds of external gates.

For reference, here is a picture of a Tial wastegate.

http://turboaddictionparts.com/catal...L38-225225.jpg

yeah top port not bottom.

Thats embarrassing that the company tuning didn't see that.

sooooooo.... you dont have a line going to the top port for your ebc... it was surging with PW because you had the EBC on the lower port?

No, this is even more dumb than that guys.

Look:

Attachment 241511

This is major derp.

OK see the big purple mushroom?

That has the spring and the diapragm inside.

That pipe connected to it goes to my wastegate.

That unconnected flange is supposed to be bolted up to my manifold- that orifice has the wastegate valve.

The top port is supposed to VTA unless you are using a boost controller.

So the lines were hooked up properly, but the fucking thing was upside down.

HOLY RETARDED SHOP!!!!! Hopefully nothing got messed up with the wastegate... how many cars did you say they have put together? For future reference, heres the tial diagram hehe.

hahahaha

7 hours of my labor later the fucking shit is all back in place facing the correct direction. I would really like a full v-band setup.

I looked at the diaphragm and it was aok. The valve shaft was kind of sooted up but I lubed it up and it is fine.

Oh I forgot to mention that when I took the gate apart to check it out, vengefully, I put 20psi worth of spring in there before reassembling.

Rofl, where is buffons fail award

This is great!

haha amazing.

i couldnt tell from the pics which side was feeding... i thought you had a 90 on the mani.


but now you should get some legit boosts and make mo powa

Not sure why you'd want a 20 psi spring. You'll never run lower than that? A 15 psi spring should be good to whatever boost you'll run.

So did the shop install the gate that way, or did you?

Obviously this WG is going on a Cummins.

Well, the more spring pressure in the gate, the quicker the turbo will build boost, even with a boost controller. With a wussy spring it will start to crack open much earlier. When I had my 9psi spring I built boost much more slowly than on the stiffer spring.

And 20 psi for no other reason than the one that made you choose to put a 400hp motor in your car :)

The shop installed my gate.

I have a 7psi actuator and a 15 for my turbo. I tried both and with a mbc the car hits boost at EXACTLY the same rpm and there is no difference whatsoever. You have to remember that the exhaust plumbing isn't insanely pressurised. Esp on your car with a large turbo, free flowing exhaust, and external gate. Unless you got a SHITTON of flow it really doesn't need a 20psi spring.

Most factory turbo cars come with low pressure wga's. Evo's/STi's/WRX's all come with 7 or 10psi spring stock. Yet those cars boost well over 20psi on the stock wga and hit boost exactly the same as with stronger springs. AS LONG AS there's a boost controller connected.

Congratulations!
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I would run away from that shop. After they pay me back for the dyno time. But good luck with that.

My reason for that was exactly what you are facing now. 30 different failsafes and plumbing nightmares to reach a simple goal. And then taking half of it out to pass emissions. Can't beat a factory PCM and simple normally aspirated power. Now if only I could finish the fucker.

Indeed. If the LS was an option in 2006 I would have gone for it. The cost is ending up pretty similar. Oh well if wishes were horses we'd all be eating steak.

Where is your build thread?

Aww fuck, my avatar.

you assholes :`(

:laugh:

What did u lube it with and why?
Its not a blow off valve, this thing gets insanely hot. So unless u used some special lube that isn't affected by any temperature then that lube will just turn into an even bigger layer of soot

Please let us know what shop doesn't even know how to install a Tial wastegate. Do they use monkeys to assemble stuff? Holy stupid techs.

I haven't updated it at m.net in a while. I redid the exhaust with v-bands, pulled the fucking dash out again to rewire some shit, and am installing the Dakota Digital speedo converter box because my speedo is whacked out. I'll be doing that tomorrow and the car will at least ride around the block.

I still need to order and install a new FM/V8R oil pan as my modded f-body pan is leaking at a weld. I'll updated the shit if I'm not too lazy to take new pics/vid.