Ok, I have an evo ix with a buschur 3in turbo back/test pipe, no flash, no tune or boost controller of any sort. Now I've read that putting exhaust on actually lowers the boost but this weekend I installed my defi bf (electronic) boost gauge and when I get on it in 3rd or 4th gear I get a quick spike to 23-24psi and then it tapers back down. I know 20.5 is usually right on for a ix and the idea that exhaust lowers boost make me confused on how I'm hitting 24ish psi. I tapped the same spot evo moto uses on their how to for the gauges...any suggestions?

 

you are getting a quick spike to 23-24 psi because a tbe actually raises boost, not lowers it.

 

You read wrong. Adding an exhaust will cause an increase in boost, not a decrease. Just get an MBC and turn it down a point or two.

 

Yes, I concur - you read wrong. I'd be curious to see where you read that a TBE lowers boost. It does quite the opposite without any boost control - it reduces backpressure, thus causing you to spike much higher.

 

Actually warrtalon it was one of your posts.

This is the thread:
https://www.evolutionm.net/forums/sh...d.php?t=194493

This is the post:
https://www.evolutionm.net/forums/sh...28&postcount=9

 

Ah, yes, that's different. You don't quite understand the point of what we're saying here and what I was saying in that other thread. In that case, the IX ECU is known to physically lower boost in some cases in order to counteract the additional airflow. It reacts and lowers the boost. What we're talking about here is when there is less backpressure, which frees up boost and causes it to run higher than stock. This is what happens on VIIIs. I have no idea why your IX ECU is not compensating for the TBE by lowering boost. That is very strange that yours is behaving like an VIII. Either way, it's a lesson on why it makes no sense to just install an exhaust with nothing else. It's far more expensive than other, smaller mods (mbc and flash) that allow you to keep your boost in check. An MBC + flash also makes a lot more power than a TBE while costing less than half the price.

 

Well I stated I had a ix and that it spikes and then tapers with exhaust on, figured that was enough info. I have a mbc and I'm awaiting two more pieces before I go get flashed.

 

Enough info for what?

If you have an MBC, then it should have been installed before or at the same time as the exhaust. No reason to wait. Get it on and regulate your boost.

 

Ok, I told you I had a ix with exhaust and no mbc/tune...I asked why I was boosting so high and everyone in this thread said exhaust raises the boost and where I got the crazy notion that it lowers it. I posted something where anothe ix with no mbc/tune was supposed to make less hp due to running less boost due to exhaust going on and now its slowly going off topic to that I need a mbc and a tune and not an exhaust.

 

No, the exhaust is great. The point is that you need to do an MBC with the exhaust or a flash with the exhaust. That goes for any year Evo, but mainly for the IXs. You said you wanted to wait on the flash until you had a few more mods, but you already have an MBC, so why wasn't it installed? It should have been installed with the exhaust - why wasn't it? Then, the moment you saw your boost spiking uncontrollably high, why didn't you then install it? I'm confused.

Anyway, I just didn't notice you said IX at the beginning. We spent 3 years dealing with people adding TBEs and no other mods then coming on here asking why their boost was spiking so high. That's what we were all referring to, but on the IXs, which are new, the ECU USUALLY compensates by lowering boost if there is no boost controlling device. In your case, the boost went UP like on an VIII, which makes little-to-no sense - I can't explain why. Regardless, you have the device you need to control this, but it is not installed for some reason.