Camphasing

iTrader: (3)

I have an Evo 9, and recently was tuned, the car is pushing around 25 psi however whenever I am in high gear such as 4th or 5th, i hear a fluffing coming from the front driver side of the car, as if air was leaking, and the car tends to stutter, the moment the fluffing stops, then acceleration becomes constant. I am wondering if you guys have had the stock evo 9 bov leak, under these circumstances? If so can u offer any advices. Thanks.

krazirob

iTrader: (12)

could be knocking, mine did that when i street tuned mine and i was gettin a couple counts of knock at my high gears.............but once i dynoed her out i havent had a problem since.

what are you afr's looking like when this happens if you have a gauge??

Camphasing

iTrader: (3)

no gauge on afrs yet

Curt@MrLed

iTrader: (107)

If you down shift you wont have that problem. You should not be boosting that high in top gear at low rpm's. Downshifting will solve your problem.

Or get a stock plastic bov with a softer spring.

The bov is supposed to leak unless under full throttle. Maf needs to read air. The bov is made to leak. If driving the car as stated above the bov is not working correctly and it causes fluttering which causes the maf to get a bad reading and then causing the car to buck.

Again you choice is downshift or buy a plastic stocker. But a plastic stocker will not hold full throttle 25 psi. There is no happy medium.

Wow I actulally explained something instead of yelling search.

This why ssqv's suck. they dont let ir escape while under part throttle, thus causing the turbo to work harder and causing a lean condition.


If anyone wants to argue my point go screw.

Camphasing

iTrader: (3)

can anyone confirm the information above?

EVOlutionary

iTrader: (38)

I went and screwed, so now I am here to argue your point. Not true. At all. Go bye bye.

To the OP, don't trade your BOV for the crappy VIII BOV. Please tell us all your mods and maybe we can help you out. Do you have cams? Are you recirculating (should be!)? Do you have the stock turbo? Do you have an intake? Stock ECU? MBC or EBC? Are you talking about partial throttle or full throttle??

I have a highly tuned 9 running the stock BOV and I can accellerate slowly from 1500rpm in 5th gear and I don't get any BOV stutter. However, I did have an EVO VIII that had HORRIBLE, actually undriveable stuttering issues and it turned out to be a cam problem . . .

Give us more info and we will help.

EVOlutionary

Curt@MrLed

iTrader: (107)

https://www.evolutionm.net/forums/search.php

Curt@MrLed

iTrader: (107)

Anyone can accelerate and not have issues. He is having part throttle problems, not accererating issues. Unless you have had these problems you have no idea what I am talking about. But hey what do I know, I have only owned 2 evos, experimented with 11 different types of bov's, over 10 different versions of my own modified stock bov's, am currently desighing my own bov with an electric motor to help stop leaking and prevent part throttle flutter, (awaiting patent) have talked to the manufactures of these bov's. But hey I have no idea what I am talking about. I havent spent 3 years trying to make the perfect bov.

Camphasing

iTrader: (3)

AMS FIMIC / INJEN PIPING WITH INTAKE
HALLMAN MBC
BC 272 CAMS
turbo back exhaust
Yes, BOV is recirculated
Yes, I have the stock evo 9 turbo
tuned on the stock ecu

The issue happens mostly when it is building boost in high gear.

EVOlutionary

iTrader: (38)

Dang DaFarmer, you edit fast!!

I have owned 2 different EVOs, 6 BOV's, and know exactly what you guys are talking about. I actually scrapped my first EVO build at a huge loss and changed tuners just because of this BOV issue that could not be resolved after spending many thousands of dollars and switching turbos twice to try to "fix" it.

I took what I found DIDN'T work on my first car and now have an awesome car with absolutely no surging or stuttering issues. EVER.

Curt@MrLed

iTrader: (107)

last point, a stock nine has a stiffer spring than an 8 bov, so with a 9 bov the issue is more prominent. Dont believe, ask anyone with a ssqv, they had your problem, but ten times worse. Its when the engine load decreases but the boost stays up cause the bov doesnt release, so the maf corrects, engine load changes, and then the bov starts to flutter. Find someone with a 8 bov and your problem will go away.


Im done.

Curt@MrLed

iTrader: (107)

same here, except i had an autronic in my 03, and every big tuner told me i was full of it. This problem doesnt exist.

Sleeping pill kicked in so I have to type fast, which causes alot of typo's.

EVOlutionary

iTrader: (38)

Thanks for the info. Sounds like you have a pretty normal mix. A few more questions to get to the bottom of this.

Does BC stand for Buddy Club or Brian Crower?
Do you have adjustable cam gears and what are they set at?
Where is your boost source of the Hallman coming from? Turbo outlet nipple or manifold? Is anything else connected to this line?(same MBC I have - a good unit).
At what RPM do you hit peak torque?
Estimating, at what RPM and throttle position does this happen most? Low RPM, full throttle. Mid RPM, Mid throttle, etc. . .

The stock turbo (or 20G) CAN work great with the stock 9 BOV. It all depends on your combination of parts, including cams, cam timing and tuning. . .

EVOlutionary

Camphasing

iTrader: (3)

so, from what i can take, this is normal operation, and under W0T the car will not leak boost through the BOV. The reason for the stutter is due to the bov opening during partial throttle in order for the maf sensor to read correctly.

EVOlutionary

iTrader: (38)

Yeah, I had an AEM EMS in my first and they still couldn't "tune it out". Ended up being the cams lighting the turbo off too fast, causing it to flow too much air at low throttle openings and low rpms. . . BISH made 390ft# at 3000 rpms, though!!! Highest I've EVER seen on a 2.0L EVO.