Hi,

I removed my carsound cat. on monday because it was broken. Since then my wastegate can't control the boost like it used too. My boost used to be set at 7psi. Now the boost first go to 7psi and stay there until vtec and then the boost goes up slowly as the revs gets higher. At 7500rpm its boosting 11psi.

Any solutions to this problem?

PS: I have a GReddy Manifold and turbo with a custom 2.5" DP and a 3" exhaust.


Modified by Maxime at 5:50 PM 10/2/2003

 

By removing the CAT your decreasing the amount of backpressure against the turbo and allowing more exhaust to move out the downpipe. Basically you've decreased the pressure and the turbo has the ability to take advantage of this by pumping more air now that is isn't restricted. Your turbo should also be spooling faster than before, again, pressure change. What your experiencing is called Boost Creep. If you have an electronic boost controller, you can solve for this by adjusting the balance(will depend on your controller), if its manual, you can lower the setting somewhat. Whats happening is your turbo is flowing more air than before, and your wastegate can't release enough exhaust to compensate for the increased flow, causing it to back up exhaust and continue to build boost. If its an internal wastegate then this is somewhat more difficult to fix and i wont go into that. If its an external wastegate, Check your port sizes on the manifold and wastegate. They should be almost if not exactly the same, otherwise the wastegate can't expel the amount of exhaust needed to maintain stable boost. Your downpipe to exhaust is also causing pressure differences, the 2.5-3inch is creating a kind of "vacum" as boost increases. This shouldn't be causing that big an issue, as you would probably see a greater increase in boost if you were running open downpipe. Try adjusting your boost controller and checking for leaks in your exhaust system around the wastegate. Probably and hopefully its that simple.

 

Thanks!

Unfortunatly its an internal wastegate. I am using a turbosmart manual boost controler.

Dammit!

 

you can try porting the WG, there are a ton of info on how to about it.
the stock internal WG are incredibly restrictive
Stan

 

Well after ready thing post.

https://honda-tech.com/zerothread?id=454167

I think I will try to advance the timing and put back my dyno settings.

Right now I am retarding the timming 1.5deg/psi. Since its getting real cold outside (Canadian winter ) I guess I can run more timming without any problems. And we have 94 octane gas here in Montreal.

I will also put back my dyno settings. Since the boost creep I tuned it way rich just in case I boost over 10psi. My car was tuned for 7psi. I was scared to run too lean.

I hope I can fix that problem.

 

By decreasing backpressure your boost psi should DECREASE NOT increase.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Muckman &raquo;</TD></TR><TR><TD CLASS="quote">By decreasing backpressure your boost psi should DECREASE NOT increase.</TD></TR></TABLE>
Huh? Should get much better flow out the exhaust, = more boost. Porting the wastegate should solve your boost creep.

 

I have no time and/or money to remove all that to port it. If I can't fix the problem it will stay like that until I install my built block next summer.

 

Well I tried it tonight and it didnt change a thing. Except my car is a hell lot faster. lol

First gera is fine (7psi)
Second is fine until about 7000rpn where the boost start to climb. (10psi at redline)
Third suck. I have the usual 7psi at 4000rpm to 6000rpm then it clim all the way to 12-13psi.
I bet fourth gear is worst.