Boost problems

[Grey Vw]

I am having problems understanding my car. The boost is not coming on normally. All of this is with a vj 11/14 with the wastegate ported and a 2.5" downpipe.

Stock intercooler, air box and ecu: Full boost (13 psi) at 3k. It held there all the way up to 7k.

Starion intercooler, rocketman ecu , open element air filter: Boost (10-11 psi) at 3k. Then boost comes up to (13-14 psi) at 6k.

I tried switching out the ecu's and it did nothing. Adding a 255 Walbro did nothing as well. I have boost leak tested it and there is only two tiny leaks at the throttle body gasket and idle screw. I have no boost controller and just have the boost cut unplugged.

[91mcnasty]

Does it only boost creep when doing a 3,4,5 gear pull? Or in all gears, because alot of boosted cars I've had experience with creeped possibly a pound or two in higher gear pulls.

[Grey Vw]

Does it only boost creep when doing a 3,4,5 gear pull? Or in all gears, because alot of boosted cars I've had experience with creeped possibly a pound or two in higher gear pulls.

I can't say about 4,5 because i've never done it. 1st and 2nd only see 10-11 psi. I ported the wastegate as big as it goes so I shouldn't be having boost creep.

Another thing to add. All the mods netted me a negligible increase in the 1/4 mile. I just tried running no filter and that did nothing as well.

[gorgonheimer]

Move the vacuum line for wastegate from right out of Turbo to intake and see what happens. Sounds like the intercooler is giving a psi drop.

[Grey Vw]

Move the vacuum line for wastegate from right out of Turbo to intake and see what happens. Sounds like the intercooler is giving a psi drop.

That is the way it is plumbed at the moment. The vacuum line is coming out of the intake tube, the same way it was with the vj14. The vacuum line on the turbo is capped off. Wouldn't the psi drop affect it at 3k too though?

[Grey Vw]

Bump for more help, it feels like vtec.

I got the boost controller on there and I can see it do the same thing in 2nd gear now too.

[sasquatch]

http://www.miataturbo.net/showthread.php?t=47532

edit... nevermind... that link wont help you... i though you have a boost drop... still a good read tho lol...

[FestYboy]

you need a bigger waste gate! that's why you're seeing boost creep (restriction at wastegate)

[bhazard]

You're running a rocketchip right? 14 psi is fine.

[Grey Vw]

Yes I am. I think I may have found the problem though. Either my wastegate flapper is hitting or my wastegate is broken and not opening fully. Fastivab6tg25mr told me to make sure it can open all the way when I made my downpipe and I did but i'm about to open it up right now and see what's going on.

How many degrees of articulation should the flapper arm have? I'm testing it with an air compressor and am getting about 30 degrees of articulation. I'm thinking it should open atleast 45 degrees because 90 degrees would be fully open..

[Grey Vw]

I took the down pipe off and compared the wastegate opening to my other turbo and it is opening normally. I went for a drive with no downpipe on and it's pretty much still doing the same thing.

I've made the boost controller cap it at 16 psi but it's still doing the same thing. 11psi=3k 16psi=5k (It got up a little faster this time).

I can hear he wastegate working(whooooosh). Maybe it's normal? I'll get a video of when I go to the track, it's not very safe to be doing it on the street or the freeway on ramp.

If it's not normal should I just restrict my exhaust? I have a catless turboback 2.5" with one muffler.

[FestYboy]

if you're worried about over boost, why not have your BOV dump boost as well?

[sasquatch]

if you're worried about over boost, why not have your BOV dump boost as well?

overspooling the turbo like that is bad....


can you port out your WG any more or is it maxed out?