If you could post up a thread for that it would be awesome . So many guys have problems doing a leak test .

I shall do it, it's super easy.

Cleaning the MAF didn't do any good, so that's out of the question. Moment of truth is tomorrow once I hook the machine up... Other than that, like Brett just told me earlier, I may be chasing my tail here. :Wconfused

Yeah man, I bet it's not a leak. I went thru several intake setups and each one required me to scale the MAF for each one. The MAF scaling being off can cause all kinds of wired issues.

Jaemeson; stop breaking shit! :fruit:

I used to think Jaemeson and Jazzmeson were two different people . So confusing .

Didn't find anything from the smoke test. Looks like we're good to go from here after we scale the MAF.

Tuning is delayed yet again. I attempted a 3rd gear WOT with stable AFRs, but experienced a bad boost spike from just under 6 PSI creeping past 8 to who knows where... I'm using a 7 PSI wastegate actuator, so I'll have to check and see if it's having trouble opening. This occurred past around 6300 RPM approaching towards 7K RPM. The car definitely wasn't happy and it seemed like I hit fuel cut and tons of smoke came out the rear. Not to mention a loud crackle when it occurred, most likely detonation. Motor is fine though, drove it casually with vacuum sitting at 850-900 RPM/16.2-16.8 Hg at 1,500 ft altitude.

Any logs from this? Any flashing CEL or codes? Vacuum testing the actuator is easy, it may need adjusting.

No flashing CEL when it occurred. All codes are just typical catalyst and air pump codes which were all removed. Me and gregs tested the actuator before install and was moving freely, but we'll have to do a double take and see if it's having trouble opening as it sits.

My bet is that you just need to mess with the boost controller some more. Mine took forever to get dialed in and I am always improving on it's setup. Also, check the boost cut feature. On mine (HKS EVC-S) I had to mess with the percentage that it cuts boost when it hits the set limit. If the percentage was too high it would cut boost too much and abruptly.

If you can fit one on your setup I would look into a Turbosmart internal wastegate actuator, they are nice. Your wastegate might just be being pushed open from exhaust pressure.

We're actually relying on the wastegate spring for the meantime since the controller hasn't been plumbed yet; it's set at 5 PSI. We ruled out the actuator and the wastegate itself, they have no trouble opening after testing again earlier. I gave it another WOT in 3rd with the WG tied open this time and it's still overboosting approaching past about 6 PSI once it hits close to 6000 RPM. Backed out right away since it creeps up so quickly...

My setup is/has been very similar to yours, and mine behaves as follows: With my WGA spring measured at 9psi, I was seeing no more than 7psi of boost (exhaust back pressure blows the WG open). With the WG unlatched and swinging freely, I saw no more than 4psi, and this was a very predictable linear increase in pressure, only seeing 4psi near redline.

It sounds like the exhaust flow through the turbine housing and out of the wastegate is severely restricted. Have you got any pics of the hot-side outlet of the turbo showing the wastegate flap and how far it can open?

Also, I mentioned previously about the inlet to the turbine housing from the exhaust manifold. It possible (though probably not that likely) that this area is causing excessive backpressure, which may be contributing to your issues. Do you have any pictures showing how rough/smooth that area is?

Unfortunately, these are the only photos I have prior to installation. Turbo was rebuilt by ATP according to previous owner before I bought it.

https://cimg8.ibsrv.net/gimg/www.rx8...0b56a6b63c.jpg

https://cimg9.ibsrv.net/gimg/www.rx8...0ce3458607.jpg

https://cimg0.ibsrv.net/gimg/www.rx8...df7c76bb9b.jpg

Looks okay, but I spy a crack that may be an issue eventually. Hook that boost controller up man.

Yup, hence the photos prior to buying the kit. I'll get to work soon and finish it all up though.

Looks like the turbo has to come off. We're still having problems controlling boost pressure. Hitting 9 PSI by 5700 RPM with the wastegate left open! Who knows how high it crept up past that when I was hitting close to 7K... Once it's taken apart, I'm going to enlargen the port significantly and look for any other possible restrictions. Unfortunately, this is a problem beyond what a boost controller can fix...

Boost creep is almost always a wastegate issue. Sucks you have to take it off. Welcome to the world of boosted RX-8's :)

Yeah, it's too bad that wasn't the case this time. :(

Other notable mods I currently have, but may not really a play role aside from the exhaust is a TurboXS cat-back and cat-less race pipe, 4.77 final drive, and 8 lb Racing Beat flywheel.

I wonder if the turbo rebuild was botched.

Good question... ATP is very reputable here, but at this point I really have no idea anymore.

I developed the SARX Greddy wastegate actuator with ATP, they were excellent to deal with in sending a spare Greddy to them and going back and forth with changes to the design, etc. I'd be surprised if they screwed up the rebuild.

It's pretty unusual . Never heard of this on this turbo before. Only thing I can think of is that Jaemeson's exhaust has much less backpressure than others with this setup.