Weird Stutter under boost

[CanadianTSi]

Ever since installing my E316g, FMIC and 650's I've had this weird stutter when I'm "gently" boosting.

If I floor it and build boost quickly the car feels fine and pulls strong and will hold 20psi fine, but If I slowly get on it and build 5 or 10 pounds and just keep it there the car will start to buck and jerk (it feels exactly like a boost leak) and it even seems like I can hear the BOV going off even though i'm still on the gas.

Anyone have any Idea's as to whats going on??

 

[kxcntry99]

I get the same thing on my stock trubo. I was going to post my own thread about this but I see I am not alone with this problem.

I was thinking that maybe the injectors are dirty or that my clutch was going. I am not sure which though.

What do you guys think?

 

[eclipsefwd]

The same thing happens to me when I am part throttle making a little boost. I have a Tial BOV and have not put a lighter spring in it yet to stop this though. But what I think is happening is that the BOV is fluttering and that is what is causing the jerkiness of the car. I know it is the BOV on my car but I am unsure if it is what is wrong with your car. I am just throwing some ideas at you.

 

[92AWD_VDSM]

Ever since installing my E316g, FMIC and 650's I've had this weird stutter when I'm "gently" boosting.

If I floor it and build boost quickly the car feels fine and pulls strong and will hold 20psi fine, but If I slowly get on it and build 5 or 10 pounds and just keep it there the car will start to buck and jerk (it feels exactly like a boost leak) and it even seems like I can hear the BOV going off even though i'm still on the gas.

Anyone have any Idea's as to whats going on??

I wish one of the moderators would help with this one... I am having the exact same problem. I am running a type-s with a super 20g front mount injectors clutch etc... I have yet to find the problem. Although i can say that it has been getting better and better the more vac. leaks i fix.. The stutter i have starts at about 10psi and goes to about 16psi. I can hear the Bov fluttering open and shut and that means during that time U are experiencing a boost leak. I have replaced with a new type-s ... same problem. Not sure what greddy rates this BOV at but the stiff Greddy Type-R is rated at 16+. I cannot keep the BOV from opening.. Is it just too weak??? BTW it is adjusted as tight as it will go...
Please help my car is running like crap and i feel sick...

 

[ziggi's92tsi]

take a log with your pocket logger while it is doing it, what do you have for tunning tools? afc

 

[miden]

Check the gaps on your spark plugs. Mine did the same and it was the plugs...

-M

 

[swing lo]

I have ngk bpr7es's and as far as the spark gap, don't you gap them to factory gaps spec's right?

 

[miden]

I have ngk bpr7es's and as far as the spark gap, don't you gap them to factory gaps spec's right?

Yeah. Might want to check your wires too. Cheap & easy...

-M

 

[Jahjahpoet]

I thought that you gap them below factory specs... I thought they are gapped at like .34 or somthing... and u can gap them lower... oh well.. I dunno... I gapped mine to .28, and no problems..

 

[diambo4life]

Do this.

1. Check your spark plug gap. Gap it to 0.028". Better yet, buy new ones and gap them.
2. Test your wires for resistance or better yet, buy new ones...or swap some from your buddies well running car.
3. Swap your coil with a buddies and check to see whether the problem disappears or not. Do the same with your ECU.
4. The first thing you should do though is to thoroughly pressurize the intake. IC pipes, IC, BOV, T/B elbow and shaft seals, injector seals etc.


I am yet to meet a person who didn't fix their "stutter" by going through that simple check list.

 

[CanadianTSi]

I wish one of the moderators would help with this one... I am having the exact same problem. I am running a type-s with a super 20g front mount injectors clutch etc... I have yet to find the problem. Although i can say that it has been getting better and better the more vac. leaks i fix.. The stutter i have starts at about 10psi and goes to about 16psi. I can hear the Bov fluttering open and shut and that means during that time U are experiencing a boost leak. I have replaced with a new type-s ... same problem. Not sure what greddy rates this BOV at but the stiff Greddy Type-R is rated at 16+. I cannot keep the BOV from opening.. Is it just too weak??? BTW it is adjusted as tight as it will go...
Please help my car is running like crap and i feel sick...

Are you venting your BOV?? if so that is your problem.

 

[PieTSI]

The problem is that because you are using an S-AFC as a tuning tool, there are only 2 ranges of adjustment for high and low throttle. I have the same problem with my S-AFC but I learned to deal with it. It will work fine for high throttle and low throttle, but when boosting around 10psi(like midrange throttle) acceleration becomes rough. The bigger you go on injectors, the more noticeable the problem will be. You can try to adjust it a little better by playing with the throttle points where the high and low settings engage, but I don't know how much it will help.

 

[CanadianTSi]

The problem is that because you are using an S-AFC as a tuning tool, there are only 2 ranges of adjustment for high and low throttle. I have the same problem with my S-AFC but I learned to deal with it. It will work fine for high throttle and low throttle, but when boosting around 10psi(like midrange throttle) acceleration becomes rough. The bigger you go on injectors, the more noticeable the problem will be. You can try to adjust it a little better by playing with the throttle points where the high and low settings engage, but I don't know how much it will help.

It does only have 2 ranges but for anything in between it averages out your settings...