after installed a BOV and fell the engine jerk when shift gear??

[ryancn]

hi good evening everyone,

i just got a blow off valve install in my mps 6.
i didn't discharge the battary beforehand but just took the stock BOV off straight away and pulged the new one on.
and i didn't connect back the air outlet hose but instead i got it block so to let the air vent to atmosphere.

after the BOV installed, when i let go the accelerater to shift gear, i feel the engine jerks..
it occurs right after i let go the accelerater, especially above 3000rmp in 2nd gear..

i heard that it's better to discharge the battery before install SRI or CAI,
and should let your car idle a while to let the ECU get used to the new filter.
so i assume i should have done the same thing for a BOV? because now less air get back into the air inlet pipe so need to get the ecu relearn?

or maybe it's because the engine mount loose so cause the engine jerks?

if it's due to the ECU, how can i get it relearn? or if it's because of the engine mount, how do i check which one got loose?
are there any other possible reasons to casue the jerk?

ps: the car is currently 59,000kms. the only mods are the BOV (installed 3 days ago and the jerk occurs after that) and the K&N panel filter (installed today). i didn't discharge the battery before installment in either cases.


many thanks in advance,
ryan

[guitar69]

Hi Ryan.
It's not necessary to fully discharge the battery when doing these kind of mods, but disconnecting it for 20 minutes or so, then reconnecting, then driving "sensibly" for 50-100 k's will assist the ECU relearning.

Pete.

[kevstewart]

How do you mean you didn't connect the air outlet hose? What type BOV you got? Dual port turbosmart with blanking plug?

[Doug_MPS6]

You are probably getting the jerk because all your boost air is going out to atmosphere and none is being diverted to the turbo to keep it spooling, and the jerk is compressor stall. This is exactly why turbo-ed petrol engines have BOVs, to perform this function.

Set your BOV at 50:50, or 100% Bypass, but NOT 100% VTA, unless you have already established a VTA fuel cut in your ECU programming.

There is NEVER any need to discharge the battery. The purpose of DISCONNECTING the battery for about 15 minutes is to initiate a new ECU "learning" cycle. This does not mean, however, that the ECU will somehow learn to compensate for serious technical blunders or mechanical failures.

[Nuliaj]

If you want to bring it round today after work, I can have a look at it to check the install first.

[ryancn]

Hi Ryan.
It's not necessary to fully discharge the battery when doing these kind of mods, but disconnecting it for 20 minutes or so, then reconnecting, then driving "sensibly" for 50-100 k's will assist the ECU relearning.

Pete.

yeah i'll do. thanks pete

How do you mean you didn't connect the air outlet hose? What type BOV you got? Dual port turbosmart with blanking plug?

it's the hks ssqv. i didn't connect the hose that goes between air inlet pipe and the bov but got it block ...

[Devil MPS]

if your running VTA it will do what your saying it does regardless of what was done prior. What Doug_mps6 said i exactly right. If you want that smoothness back, go plumb back or standard. Or 50/50 like others have done

[ryancn]

You are probably getting the jerk because all your boost air is going out to atmosphere and none is being diverted to the turbo to keep it spooling, and the jerk is compressor stall. This is exactly why turbo-ed petrol engines have BOVs, to perform this function.

Set your BOV at 50:50, or 100% Bypass, but NOT 100% VTA, unless you have already established a VTA fuel cut in your ECU programming.

There is NEVER any need to discharge the battery. The purpose of DISCONNECTING the battery for about 15 minutes is to initiate a new ECU "learning" cycle. This does not mean, however, that the ECU will somehow learn to compensate for serious technical blunders or mechanical failures.

the bov is self-adjusting.. it's a hks ssqv which can't be adjusted manually ...
in this case what can i do to eliminate the jerk?
thanks

---------- Post added at 11:32 AM ---------- Previous post was at 11:29 AM ----------

If you want to bring it round today after work, I can have a look at it to check the install first.

hey Ju, thanks for that!
im not sure whether i can make it today, but i'll let you know beforehand

---------- Post added at 11:38 AM ---------- Previous post was at 11:32 AM ----------

if your running VTA it will do what your saying it does regardless of what was done prior. What Doug_mps6 said i exactly right. If you want that smoothness back, go plumb back or standard. Or 50/50 like others have done

thanks mate.
um.. my one is not manually adjustable instead it adjusts itself
im not really chasing for smoothness but just to make sure the jerk will not give me any trouble later on

[Devil MPS]

HKS can only be VTA or plumb back. The jerkiness comes with practice to getting the smoothness, or if your into the revs more where the air is pushed all the way out as opposed to some floating around the system. Over the long run you may have a blocked cat dude to increased heat from backfiring, if the jerkiness is continued over time, i'd imagine possibly some damage to the clutch

I've got a HKS SSQV3 VTA aswell, mine does the same and a mate of mine on here (Markeymagz) had his HKS VTA and said it did the same thing, but went plumb back and problem solved.

[High on PSI]

When I had the Turbosmart on it was VTA, car ran smoothly. No backfiring.

[Devil MPS]

Backfiring and all the other jazz said with running VTA info i've read came from these forums. The search function reveals interesting opinions/topics.

[TD]

As previously mentioned, don't run vent to air unless your car is tuned for it.

Plumb it back...or if you want the woosh buy a BPV which will allow 50:50 recirc and vent to air.

This highlights how you need to research before buying mods, you could have saved yourself some coin by buying a BPV which works with your car.

[Jrbris]

I've got a turbosmart BOV, if i run 50:50 car will backfire and carryone like a frog in a blender. now i have 100 % recir and the tightness nearly set to full hard i get a bit of flutter but nothing to bad. car runs smooth. i had backfire issue thou when i had a boost leak.

If the bov is too loose, it will pop and backfire also.

Thats my learnings with bov's.

---------- Post added at 03:20 PM ---------- Previous post was at 03:19 PM ----------

i also get a very loud woosh sound via the SRI.

[Doug_MPS6]

When the term "self-adjusting" is used it does NOT mean that the BOV will select between 100% Bypass, 50:50 or 100% VTA or whatever options it is capable of employing. That's something you set up with your plumbing and port blanking plugs. It is merely an indication of the fact that the spring-loaded piston is capable of accommodating varying discharge pressures. I have carefully described how to set up a Turbosmart BOV in previous posts.

[Jrbris]

When the term "self-adjusting" is used it does NOT mean that the BOV will select between 100% Bypass, 50:50 or 100% VTA or whatever options it is capable of employing. That's something you set up with your plumbing and port blanking plugs. It is merely an indication of the fact that the spring-loaded piston is capable of accommodating varying discharge pressures. I have carefully described how to set up a Turbosmart BOV in previous posts.

You got a link to the post ?

[Spudspec]

aftermarket BOVs are hard work, The Mazdas are not designed to be played with, hence why a recirc jobby always works best.. if all you want is a pushhhhhh noise, then Buy a loud speaker and one of those supercheap fake BOVs. I have seen many engines and components damaged because of BOVs not correctly installed and tuned to suit. flutters and Backfires in late model engines is BAD. unless you are loaded and can afford ANTILAG. anyways. Always need to have my 5 cents worth. cars have feelings too, and if you dont treat them right, they will not be good, and that is when you start having failures.

[Nuliaj]

Any SRI or CAI will increase the sound (the metallic ones seem to be louder) of the BPV including the stock BPV. VTA untuned is generally not recommended as you will during shift changes (while on boost) generally have more fuel than required which causes the hiccup. That said most cars run rich factory tuned anyway.

[ryancn]

thanks for all your advises guys!
i think the best thing for me to do then is plug back the hose to let the air vent back to recirc

i gotta miss that sword sounds..

---------- Post added at 05:52 PM ---------- Previous post was at 05:42 PM ----------

by the way, when you say tune the car if i want it vent to the air..
do you mean tune the factory ECU or get a plug in one? or others?

and how much does it cost if i wanna get it tune?

thanks

[TD]

Do a YouTube search for Mazdaspeed BPV or Mazdaspeed BOV, you'll hear examples of most on the market.

The Forge V1 BPV on my car sounds like a sword fight...

[Doug_MPS6]

I don't have a link to my post but a search on BOVs will probably find it.

As a general note while I have the opportunity, I didn't buy a BOV for the sound, and I'd say that doing if that is the only reason is daft, especially if you lead yourself into a path of woes tying to figure it out and tune it. Of all the after-market componentry, BOV's are, as I have written more than once before, the least understood, most mythologised and have the most BS written about.

I bought mine as a tuneable BOV so I could ensure that only just enough air was bypassed to prevent the turbo from stalling and at the same time to maintain the maximum possible amount of air in the system to ensure that when back on the throttle, the turbo didn't have to waste fractions of seconds of spool-up time simply re-pressurizing the 2.5m of FMIC plumbing.

That is the problem with going 100% VTA, is that you are at greatest risk of (in fact, you ensure that you are of dumping all) the air overboard that you really want to keep the maximum amount of in your system. I'd say that unless you are into rallying and have especially high-performance engines and are routinely flat-shifting, then forget VTA. If you flat-shift then you are not closing your throttle plate, so you turbo won't stall with any back-pressure wave, because there isn't one. A bit hard to achieve as a matter of course in you daily driving traffic so "don't try this at home". Then with VTA you have to set up your ECU (and/or piggyback controller) to cut fuel during the shift so you don't feed raw fuel into the engine when it doesn't need it, giving rise to cylinder lube rinsing and backfires.

Some people write that they feel their car is "more powerful" with a certain BOV. The BOV cannot add any power. If you have a leaking BOV, which is 95-99% unlikely, then you will get improved power by preventing boost loss if you replace it with another. But otherwise, any impressions of significant power increase come more from improved response via the successful tuning to the configuration I have described above. That seems to pose another problem, is that folks gin around endlessly with their BOVs trying to "tune" it. It ain't rocket science. Read the instructions (which I have also written about at least twice). I haven't touched my BOV in months, and that was only to clean it.