whenever i floored the gas pedal and boost hits 9psi, the car starts jerking and the tach is only at about 5000rpm. if i remember correctly this jerking started happening after i put in the greddy mbc BUT i can't really remember so i'm lost. if i accelerated gradually it doesn't do this but if i floored it then it started jerking.

my setup is not perfect yet and there's still some things that needs to be done. here are some of the negative things about my setup:
- i'm using 8:1 fmu with stock intank pump and injectors which explains why i'm leaning out. i've installed an inline pump but i can't believe that it's not working.

- something MIGHT be wrong with the mbc though not sure

so what is wrong with my car? what causes the jerking? could it be leaning out or the mbc or any other?? have any of you experienced this, what was the cause?

by the way, the car is a 99 SiR and currently got the fmu setup but soon will switch to vafc hack if i have the budget.

any help will be greatly appreciated.

 

I got rid of it on mine by changing the gap on my plugs.

Was running .044" with an Accel 300+ and had to reduce it to .035"

Get a cheap set and gap em smaller to see if it works.

 

my plugs are gap 0.032" with stock ignition. anymore?

 

i'd say somthing wrong with your fuel system. maybe your leaning out. but i'm sure its a fuel issue.

 

Sounds like leaning out to me...but thats just me. You're setup is similar to mine...and mine did the same thing. Hope this helps!

 

i hope it's just a case of leaning out coz it'll be easier to fix. i guess i have to wait til i switch to the vafc hack and see if it's still doing it.

if anyone has some more to add i would really appreciate it since it's getting annoying not to mention i might end up with a blown motor.

thanks