Over Boosting Bad

[TYTILIDIE]

Ive put about 5000 miles on my new motor in about 2 months or so. In this time I ahve had numerous problmes. One being the trans. So now I have it all running perfect and tonight I go to get down and dirty with a CBR 600. When I hit the top of frist, I got fuel cut. Same at the top of second. Heard a little backifire the second time. My CEL also came on. At the moment my laptop doesnt work so I have no way of pulling codes as I have modified my ALDL into a serial port. So I pulled over and checked the VAC lines and everything looked fine. I started to investigate a little more driving it. I noticed that the turbo was boosting extremely fast and the gauge was pegged the secondI would hit WOT. I didint do too much of this but wanted to see if I could figure it out. Does anyone know what causes this? 1/2 throttle all of a sudden is a lot faster than it was at WOT before this Overboosting issue and thats at like 10 psi or so. What hte hell is going on here? Any help is appreciated as always.

Mike

 

[93ty475]

Re: Over Boosting Bad

At the moment my laptop doesnt work so I have no way of pulling codes as I have modified my ALDL into a serial port.

probably an overboost or related code when the SES lights up.....you need to get the laptop fired up again to see what's really going on....do you have an aftermarket boost gauge? If so, you need to use gas pedal boost control if the boost is pegging out....you should closely keep an eye on that boost gauge and regulate the boost with your right foot until you get this solved....your motor might be pinging like crazy.....

I noticed that the turbo was boosting extremely fast and the gauge was pegged the secondI would hit WOT. I didint do too much of this but wanted to see if I could figure it out. Does anyone know what causes this? 1/2 throttle all of a sudden is a lot faster than it was at WOT before this Overboosting issue and thats at like 10 psi or so.

As little as a broken rubber vac elbow by the boost control solenoid or actuator has been known to do this.....it's a recipe for disaster unless you have a full tank of c16 to handle the extra boost......

 

[SeattleSy#1255]

Re: Over Boosting Bad

your boost selenoid may have took a dump...something else to consider. I say check vac. lines first as well. Are they silicone or the stock hard rubber? This type of thing would be exactly what would happen if you revmoved the vac. hose from the WG actuator and let the turbo spin freely, hence you may have a big or even small leak in that hose.

 

[TYTILIDIE]

Re: Over Boosting Bad

I havent thoroughly checked the VAC lines yet but did a quickie at hte gas staion last night. They are pretty new. I found some of the hard plastic lines and molded them myslef and used new boots and what not. This was a little over a year ago. If it was the boost solenoid, wouldnt I get a Code 31? I will go and orer one today jsut to be sure. They are cheap, like $20. Maybe Ill change out the VAC lines just for the hell of it. I do use the stock boost gauge and while Im sure its not 100% accurate, I really ccant afford an aftermarket one at the moment but hav3e had one hooked up somewhat recently and MY stock gauge seems to be on the money.

Mike

Mike

 

[InvisiBill]

Re: Over Boosting Bad

They are cheap, like $20. Maybe Ill change out the VAC lines just for the hell of it. I do use the stock boost gauge and while Im sure its not 100% accurate, I really ccant afford an aftermarket one at the moment but hav3e had one hooked up somewhat recently and MY stock gauge seems to be on the money.

My (and I assume all others') boost gauge is somewhat accurate. Cruising at a steady pace, it's pretty close. However, any time there's a large change in boost level, the stocker is way off. I've seen it show well over 15psi, while my Autometer showed just over 10. The fact that it's electric means there's simply some "play" in it. I wouldn't rely on the stocker for anything more definitive than whether it's in boost or vacuum, sometimes maybe "a lot" vs. "a little". The fact that the stocker can be dead on sometimes and completely wrong other times is even more reason to get a good mechanical gauge, in my eyes.

You can get an Autometer 3301 (2 1/16" Sport Comp, 30 in. Hg/20psi) for under $43 at http://www.egauges.com/. You can get a nice PnP fitting for it from Ron Gregory for under $10 at http://www.autoperformanceengineering.com/html/boostkit.html.

I totally understand not having the cash to get/do every single thing that everyone here recommends. However, boost is one of the leading causes of major problems. Especially if you consider $20 cheap, $50 for being sure of exactly what the boost level is seems like a no-brainer to me.

 

[TYTILIDIE]

Re: Over Boosting Bad

Yeha I actually hooked up my Mech Boost gauge today and it was way off. My boost gauge says (at WOT), 10 psi and the mech said 14. I got the new solenoid today and the truck feels like a dirty dog. It seems to spool super slow. I dont like this at all. Now I am on a mission to find a way to get this thing to spool like it has no control but it does, dont know if thaat makes sense. I cant settle for the way it is now. Im thinking that this solenoid has been going bad slowly cause I notice a huge difference in every way it drives now. I adjusted the actuator cause I was only at 11 psi total so I decided to hook up my mech and do some adjusting. I want to put in my AFPR but had in there last week and the FPgauge was all over the place. My turbo has a GT30 wheel in it so thats why I got the AFPR. Is it possible I can see more power with that? Anyway, Im going to make a post asking how to get this tyhing to spool super fast like it was if noone here has any ideas.

Mike

 

[SeattleSy#1255]

Re: Over Boosting Bad

One of the ways to get these things to spool fast is chip burning...causing the WG to stay shut as long as possible before it opens, however to do so, you need a WG that is properly sized such as an external gate or a properly matched size internal such as what are on the PTE kits. So it was the selenoid that was going bad? Keep in mind it may actually only feel like a "dog" now because the past few days the turbo was spinning freely...you may have just gotten use to it.

You won't really see more power with the AFPR, but you'll be able to control your FP, one of the many numbers in the tuning equation.

 

[TYTILIDIE]

Re: Over Boosting Bad

Yeah and my frined were tlaking about how I must have gotten used to it lastnight. What is a decent External to get that is fairly priced. Not saying the cheapest, the good quality for fair price? Do I need a boost controller with it or can I just use the WG? My only issue with externals are the exhaust thinmg. I know itll be a PITA but if thats what I gotta do thats ok.

Mike

 

[InvisiBill]

Re: Over Boosting Bad

A wastegate alone is nothing more than a controllable flap in your exhaust. You need some sort of a boost controller to make the wastegate do stuff.

You should be able to use the stock solenoid and stuff with an external in a "single port" setup. However, externals have dual ports, and work much better when you use both. In theory, it should be possible to modify the stock boost control code to work with a dual port external, but I don't think anyone's done it yet. Most people also seem to think the stock boost control code isn't all that great. So you're using poor boost control methods, hooked up poorly to the wastegate. Probably not a great solution without a lot of time chipping...

A BoostValve (a.k.a. Grainger valve) is simply a pressure valve. When it hits __psi, the valve opens and pushes the wastegate open. It's very simple, so it's cheap. It also tends to work pretty well since there's not much complication to get in the way. However, that also means your ECM has no control over boost in relation to other stuff (like knock).

The most exact way to control boost would be with a separate electronic boost controller. It's basically a separate computer dedicated just to boost control. They can do all sorts of fancy stuff now. The main downsides are that they're separate from the stock ECM, they may require their own MAP sensor added in somewhere, and they're relatively expensive.