Dyno testing is easy enough to find and if you want a track day just find your local drag strip and go on a "test and tune" night. You can make a lot of runs for around $20. IMO track time is a lot more valuable than dyno testing. According to my heat-soaked dyno results I should be running 14.8 @ 93 mph.

As you may have noticed, my sig is a boast but equally a challenge. I'm just waiting for someone to post a quicker time slip to make me change it.

BTW, you may be right about improper maintenance causing 99% of post-turbo issues but unfortunately I fell into the 1% with a mis-wired FIC harness, defective FICs and still unknown faults with the APR X-1 and/or Dezod harness. I only mention this to illustrate the lack of proper R&D present within the aftermarket that caters to such a small customer base as Scion. The mis-wired harness had never even been tested on a XB before I received a "production" sample. AEM's lack of QC is well known but mostly ignored because the FIC is so cheap and therefore popular. I won't even get into how much is wrong with the Dezod/APR-X1 "Tacoma" piggyback that almost blew my engine.

 

So are we ever gonna get to see some more pics of your turbo setup and car? I'd really like to see more of it. I just watched Descendant's installation video and was really impressed that they went so far as to fab a custom t-stat housing for better downpipe clearance. If I were buying a turbo kit today it would absolutely be from Descendant.

 

No rush, I just wanted to make a request for more pics, when you have time.

10psi again? I see temptation got the better of you. It's been getting to me lately too. I'm considering adding a Walbro 255LH and a return fuel system so I can run 7 or 8 psi. No plans for 10psi though. You should be close to 300 whp.

 

I understand the temptation completely and wish you good luck at 10 psi. No one really knows exactly what our trans can and can't handle but we all have our own opinions and comfort level. I just want to break into the 13's and 13.9 would be good enough for me.

250-275 whp is about right for 8psi although I'm not sure how much you're giving up with that stock exhaust. 10 psi should still get you into the 275-300whp range. Below is a nifty little 1/4 mile calculator that does a good job of estimating ET based on HP and weight. Stock curb weight is 3100lbs for the auto trans so just add your weight and hp guesstimate.

http://www.race-cars.net/calculators/et_calculator.html

 

What kind of issues did you have at 10 psi?


It's not uncommon to have less boost in the intake manifold than at the turbo compressor. If your wastegate is plumbed correctly it gets vacuum right from the compressor housing and it's reasonable to lose 1.5 psi of boost to the IC pipes and IC. It's also possible that you had a small boost leak.

You may want to install some small cable ties onto all of your vacuum line connections. When in boost they are also pressurized and more likely to leak or blow off.


Vegas is only 2000' ASL so it shouldn't make that much difference. A leak is more likely. When you first had the kit installed, were you seeing 8 psi on the gauge or 6-7 psi? If you were making 8 psi and now you're making less, the most likely cause is a leak somewhere. OTOH if you've always made 1.5 psi less than the WG spring, you could lose another ~1 psi being at 2000' ASL.


You can get T-bolt clamps from many sources. I've bought them from ebay, CX Racing and ATP Turbo. They were all decent quality. You can leave the hose clamps on the intake couplers but I'd replace all the boost couplers with t-bolt clamps. Here's a link to ATP:

http://www.atpturbo.com/mm5/merchant...egory_Code=CLA

With any luck, replacing your clamps will fix your stalling issues. It may not but it certainly can't hurt anything. FWIW, I decided against raising my boost (again...). There are 2 ways I can do it but a return fuel system, FPR and pump will cost about $500 and a Greddy EMU and a tune will cost $1200+. It would be fun but it's just not worth it for another 20-30whp.

Enjoy your boost!

 

Hmmm... my best guess is that you had a small boost leak develop while in vegas at the same coupler that blew apart when you raised the boost to 10. That would also explain why you're back to full boost after re-attaching that coupler. I hate to keep harping on this but you'll probably keep chasing problems like this with those crappy hose clamps on boost pipes. They're fine for the intake and BOV couplers but not for the IC pipes. I'll bet Descendant uses T-bolt clamps on all of their race cars.

Can you post or PM me a photo of this uncapped fitting? If your WG is plumbed to the IM it could cause a vacum leak. If it's plumbed to the turbo, it would cause a boost leak and prevent the WG from opening when it should. It could also be the vent for the top chamber of the WG which needs to remain open to atmosphere.

Checking your plugs is never a bad idea. I doubt that they're fouled but they can still tell you a lot about how your engine is running. I still highly recommend going 1-step colder. (NGK BKR7EIX-8 works great for me) TRD recommends this with their SC and NGK recommends that for every 75-100hp you add you should go 1 step colder. Believe it or not, I actually research this stuff all the time.

http://www.ngksparkplugs.com/tech_su...d.asp?mode=nml

 

Dude... it seems like it's giving you nothing but problems.

My offer to trade all my audio stuff is still on the table. I'll even throw in a barely used Canon T1i. :D

 

Looks good to me and you shouldn't cap the top chamber vacuum fitting. There's a diaphragm between it and the bottom chamber so unless the diaphragm has a leak (very unlikely) there won't be any vacuum leak. If you cap it the diaphragm will have to compress the trapped air in the top chamber to open the WG valve resulting in higher boost and erratic WG operation.

I didn't know the MVS could be water-cooled. That's pretty cool (no pun intended).

I guess we'll have to keep chasing down the idle issue. It might not be a vacuum leak but that's all I can think of and probably the most likely cause. I was hoping that the ECU would have corrected it by now but apparently it won't be so easy.

 

Hush! You're obviously just trying to score a deal on a very nice turbo kit!

Coincidentally, I rarely ever listen to my stereo any more either. I prefer the sweet music of a finely tuned engine. It may not be a Ferrari V-12 or a Porsche flat 6 but it's still music to my ears.

 

You should be happy with 8psi and auto trans. Your XB is now quicker than a stock GTI, R32, Ralliart, genesis 2.0T, etc. and the only cars in this class that are still much quicker are the quite expensive Evo and STi. It's a close call with the Cobalt SS and MS3 but you're close enough to at least keep up. That's pretty cool for a $18k econobox toaster.

A gen 1 would make an excellent DD! I went with an old Subaru Legacy wagon and while it will be great in snow and off-road, it's a gas pig at 22mpg avg. 1993 technology... but hey, I can get historic tags in 2013!

It's been my pleasure to share what I've learned here in the past few years. IMO that's the best reason for forums like this to exist: to help and get help from others. If it's social banter you're looking for, there's facebook, etc.

BTW, I'm 100% confident that your idle issue will be fixed eventually. Have you tried cleaning your mass air sensor yet? Simple thing but it fixed a similar problem for a boosted TC guy recently. You can buy MAS cleaner at most auto parts stores for about $5.

 

Thanks for summarizing everything in one post like that. It make things easier. I want to suggest a boost leak test but they're a PITA and I'm hoping that t-bolt clamps might do the trick without the leak test.

As for the tune, I recently saw where a boosted TC with similar problems fixed his lean-idle/stalling issues by subtracting less fuel in the idle cell range of the FIC fuel map. Do you know how to download and upload maps to the FIC? If so you can send me your map and I'll make some changes for you to test. If you know how to change your FIC map, you could make the changes.

Your plugs look okay but could use a cleaning. Thay're a bit sooty. They don't look bad enough to be causing the stalling issue.


Keep the faith, Bro!