Car jerks during boost

[Danny]

I've realised after installing larger injectors ie. 450cc to 510cc there are some jerks between 5000-7000rpm. May I know what are the likely causes ?

a ) too rich fuelling?
b ) sparks flooded?
c ) others...

Also in hot afternoons, the temp goes up with hard driving to around Middle level compared to quarter level during night time. Is this normal?

 

[BLaCkHoWLiNG]

perhaps it's too rich.. has it been tuned properly? or jes throw the injectors in and hope for the best??? if yer spark's flooded i think
the misfiring will continue even after that...

in d afternoon temperatures climbs much more easily compared
to night time... coz it's much cooler at nite... ever noticed yer car
is much more powerful at nite or in d rain? coz it's cooler..

don simply hentam during the day la... hehehehe .. lotsa pple on
d road..

 

[Danny]

did some self-adjustments on the safc also, maybe should go for a dyno tune to be more accurate and check the sparks.

update - found out the problem already, adjustment fuel setting for hi-setting too low. Increased the fuelling and the jerking dissapeared.

 

[Danny]

took out spark plugs today to check, I was right, the spark tips were white in colour ie insufficient fuelling. Other than that, one of the tip distance is too far away and one plug cracked. Time for new sparks.

 

[BLaCkHoWLiNG]

fortunate for u... it didnt go boom

 

[SDF]

yah man...

Dan...better get some PRO to tune fer u....much much safer... ;)

 

[Danny]

yea that will be done soon once all the minor upgrades are done, now just added extra fuelling to be on the safe side. However even when there was low fuelling previously there wasn't any knocking sound.

 

[kam_bin]

Danny, how do u adjust the fuel setting?

I maybe have same problem, mine is during 1000 -3000 rpm the car jerks and feels heavy but after 3000 ok. during that time i can see my boost meter needle
keeps moving up down?

check the plugs already looks ok, maybe need to change the cable but i think still ok.

can anyone help?

thank you

 

[Danny]

I adjusted the fuel setting with SAFC. I had to adjust the low throttle setting until -25% only the car could more smoothly due to over fuelling. Next investment for me would be a air/fuel ratio meter coz now damn hard to adjust the settings without the meter, all guess work only and trial and error.

 

[kam_bin]

ok. lets say i don't have the safc can i still adjust the fuel/air mixture manually. if there is a way. sorry still abit confuse here, the fuel/air mixture is control by the ECU or mechanically in the engine?

thank you

 

[Danny]

its controlled by the ecu. You need a piggyback or standalone aftermarket ecu if you want to change the settings. There's no way to control it manually.

 

[lekalo]

kam_bin>>

sometimes, it's the stupid fuel pump, beb.

 

[kam_bin]

lekalo: Yeah i wander too, how to check if it is the fuel pump? any advice?

btw forgot to mention the engine is standard 13B only air filter change to HKS.

thank you