When secondary turbo actuators are activated and the 2nd turbo comes online, does that cause the quick 2psi drop in boost?
I did half a boost test, but only got 2 readings 5-3, I came up on a new construction site, so I had to slow down. I thought you had to reach 8psi before the secondary turbo actuators could be activated so I'm curious about what causes the drop in pressure in the X-Y-X boost pattern. With the car off, the gauge sits at 0. At idle my boost gauge reads about 18/17" vaccuum which seems kinda high for a streetported engine but she does idle a tad bit high 1.2k rpms.
So right now, I plan on doing a full boost test tonight/tommorrow and if I still get similiar results, I guess I'll check hoses and test the gauge.

my mods:
streetported engine
dp
muffler(not sure what kind, but it's louder than stock)
AST

BTW, the boost gauge is Autometer with the steering column mount from Pettit.

Thanks!

 

don't run WOT if you don't have something conpensating for a streetport...timing and fuel is different than what the stock ECU can control.

yes 2psi drop when sec. comes on line.

 

Thanks!
She runs rich now. So how should I tune the engine to compensate for the streetport? More fuel and advance the timing?

 

yes the 2psi drop in boost is normal. Your boost pattern should read roughly 10-8-10 under moderate-heavy throttle pressure. With factory "normal" boost setting you should get 10psi on primary then an 8 psi reading during the transition, followed by 10psi on the secondary, (10-8-10).
Also, as stated above I hope you are running an upgraded from stock ecu with your dp and streetport. Otherwise Wide Open Throttle runs could spell disaster-- KABOOM!!

 

Ok, but I thought the conventional wisdom on the board was with my current mods, I wouldn't need an upgraded ECU until I removed the cat and replaced it with a midpipe.....

 

yep my bad, I read the post quickly, saw dp and thought mid pipe. You are correct no needy upgraded ecu with your mods until you replace cat with mp.
Still it would not be a bad idea to get an upgraded ecu soon, especially if you plan on future mods. there is only so much you can control with stocker ecu.

 

forgive my total lack of understanding but when you say "upgraded ecu" duz a HKS - F-con 2 with gcc fit slightly into this catagory or am i mistaken ?

i know u guys probably think this is the worst piggy back ecu but with 12mpg and fule costing £4 a gal i cant afford to change at the mo.

also fits with my worst paint job of all time haha.

 

Hmmm, I've only read of guys running Apexi's PFCs on FDs.....
http://store.yahoo.com/rotorworks/apexipowerfc.html

 

you don't need an upgraded ECU with a streetported engine? I thought you would. I am a newb on the streetported set-up, anybody want to verify if this is true? Its true on a stock 13b that you should not go past the DP before you go to an upgraded ECU as far as exhaust and intake mods. I have intake,dp and had a little spike, put a boost controller on and I am good til x-mas when I can get a Power FC. Cannot wait!! after its tuned I plan on opening up the exhaust with a high flow metal substrate cat and resonator in the mid-pipe, upgrade the fuel system, some BNR stage 3's and I am done !

 

So is it possible for the secondary turbo to come online if you don't have 8psi of boost? Do I have a bad gauge, or is it something to do with the turbo system itself?

 

A streetported engine on the stock ECU is a BIG no no. The stock ecu cannot adjust timing as neccessary to compensate for the larger porting. You need to get a standalone pronto before you pop your engine.

 

that's what I thought. I would just get the Power FC, have it tuned and call it a day. If you are not getting full boost pattern, it could be a gazillion things. Its probably in the control system for the turbos. I bet any money its the stock ECU trippin out because your timing and fuel is all messed up because of the streetport.

 

The stock boost pattern is 10-8-10. The drop in boost is due to the momentary reduction in exhaust gas to the primary turbo from the secondary turbo coming online. This is perfectly normal.

 

you should be able to get the secondary turbo to spool with at least 8 lbs of boost on the primary turbo. The primary spools the secondary then when the secondary comes online is where you get the dip and then they both run until redline. In simple literal sequential terms.

Check the link to troubleshooting the turbos, this should help you.

 

i ran a stock ecu with a dp and hi flow cat with a large streetport for almost 6 months and my engine is great.as a matter of fact the compression testing last month showed 8.9s across the board. and that was DRIVING the car not driving the car....

 

Wrong. The primary does not spool the secondary. The primary turbo spools and provides boost until a predetermined setpoint then the secondary comes online and both turbos are providing boost.

 

Thanks sonix, but that's where my question came from. I saw the gauge was reading only 5psi but it dropped when the secondary came online, so I was wondering how it could start up with only 5psi vs 8psi.

 

Update: I took off a bunch of the hoses off the car to check for cracks that might becausing my boost leak. Low and behold, the elbow that goes into the bottom of the intercooler has 4 splits in the ribbing. After I replace it I'll let everyone know my new boost numbers. I'm hoping this'll fix my problem.

 

Ok, so I went ahead and hot glued and duct taped(ALOT of duct tape) the hose and put everything back together(ordered another hose from Dave). Wow! What difference! I've got quite a bit more power now, but now I can hear a hissing noise when I'm boosting. Either there's another leak or I didn't tighten down all the clamps. I'll check everything again tomorrow. I did cursory check of the Y coupler, didn't remove it but it seemed ok when I had all the hoses off.

BTW, now my Blitz BOV that always made this SWOOSH sound when I changed gears, now makes this tiny "queef" noise. I expected now that I'm not losing as much air to the atmosphere, it would be actually louder. Not that I care about the loudness of the BOV, I'm just surprised by the change in sound/volume.