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.