Lately my turbo has been making quite an odd noise at full boost. It sounds like the BOV is venting some of the boost to atmosphere. At idle it feels like the bov is sucking air in (which it shouldnt). Also, it tries to be sequential (It'll hiss sometimes up to 4 different tones after I let off). Its a stock BOV. I've swapped on a working BOV and it kept doing the same thing. It doesnt feel like there's a loss of power and it still makes perfect boost. I couldnt find any boost leaks either. WTF is going on?

 

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the only factor that determines wheather the bov is opened or closed is the level of vacuum it is receiving from the engine.

 

vaccuum is good. This is confusing the hell out of me. Im just gonna go single and hope that solves my problem.

 

yeah ok bud
easy to do right haha

 

single is pretty easy. Greddy's T78 kit just bolts right up and comes with more than I'll even need for the job. I wish its instructions were in english, but oh well.

 

ookey dokey smokie

I've done some work on fds its gonna cost you way more than you think and its not that easy..well if you rig it maybe

 

Going single will fix the problem but that is a bit overkill.

It sounds like your CRV is stuck open ( Charge relief Valve) The valve that is connected to the back of the Y-pipe. ( It looks like the BOV)

Check the vaccum lines on that valve and going to the manifold.

Grab a vaccum diagram from Rob Robinette's site. Or try downloading the factory service manual from www.iluvmyRx7.com

If you really want to go single go ahead. But if you don't already have the engine management and fuel, exhaust for it, you are looking at around 10K including the turbo kit. Where as a vaccum line job I charge 250 for that.Plus the cost of the hose.

get that here..
http://hightempsilicone.com/


Eliminate the small things before dropping big coin.

 

Rob's site
http://www.rx7.org/Robinette/

 

Have you checked your air pump hose? Mine had a split in it, it made a sound somewhat similar to a boost leak. Try disconnecting your air pump and see if the sound goes away. Replacement hose is $10 from Malloy Mazda, or the MazdaComp program.

-s-

 

going single is nice but not because of a simple hissing sound, and also going with a t-78 kit will not solve your problem but only rape your chekbook since you will have to upgrade a lot of things to run that turbo and not to mention the lag you will be getting..

go single if you want more power not because of a hissing sound..

 

no crv, no airpump. car just needs bigger secondaries. already has 850 primaries, pfc, and all the bolt-ons

 

They can fail. I had an OEM fail and lunch a ball bearing turbo in the process and help cause an ensuing 4 year delay in driving the car. I'm actually deleting them from my setup now and going to use a single low level turbonetics one post IC (I have two IC inputs tubes on the hot side so it's a savings issue as well). It's a pain in the pooper to track down as well.

Kevin T. Wyum

 

The best way to see if it is your air-bypass valve or charge relief valve is to test it with a vaccum pump. At ~3.9in/hg, your ABV should be able to flow a little bit of air. At ~9.2in/hg, it should flow without any restriction. Your CRV shold flow without restriction at ~7.8in/hg. You can start there.

 

my car has only 2 rotors and makes 360 rwhp so I guess I should scrap it and drop a 20b in there. Seriously dude, like others have said, do the swap because you want more power, not to fix a hissing noise coming from the engine bay. That's a huge expensive band-aid to fix a very minor noise related problem since your making boost and power.

Tim

 

Ya, I know. I do want to go T78 eventually. Its not like Im jumping into it to try and fix the noise, although I still cant figure out whats causing it. I probably come off sounding like an idiot. I just get tired of explaining myself out on all the car forums. I know what Im doing. I know what it takes to go single. In fact, I know 2 people who have gone T78 that could help me along if I have any problems (The Greddy instructions arent in english).

 

okay, what have you checked? Have you taken anything emission wise off the car since you have the PFC? Did you use block off plates if you did and use a small amount of sealer on the block off plate? Are all the hose clamps on tight? Other small hoses zip tied as well to keep them from expanding or possiblly crack from old age? Just trying to narrow it down.

Tim

 

Just the other day I blew off one of the rubber caps to my twins. This was a rubber block of cap due to me going to non seq. I had no loss of boost, or very little. Sounded as if the turbos were working very hard and I also noticed my hp decrease. I thought my BOV was venting under boost. I pulled over and started doing an "all systems check." As I was checking to see if the BOV was working (revving the engine in neutral), I felt a gush of warm/hot air coming from around the turbos. After a deeper look I noticed I was missing a rubber block off cap. Replaced the cap and all is good. Check for small boost leaks while revving the engine.

I do know that if you have a boost leak your wastegate will try to keep target boost. Therefore you will be working your turbos harder to keep target boost.

 

This sounds like it may be my problem. I'll check right now.

 

Previous owner converted it to non-sequential. It has block off plates, but I dont know about the sealer. All the hose clamps are tight. There isnt a single emission thing on the whole car.