QUOTE(dares @ Nov 4 2012, 11:30 PM)
When the Campro first came out, before the CPS and IAFM, the engine "featured" a notorious torque dip between the 2k-3k RPM. That means, when at 2k-3k RPM, you will feel that your engine is underpowered, until beyond 3k RPM when the torque suddenly recovers. Unfortunately, for daily driving, especially for AT cars, most cars run at that crucial 2k-3k range most of the time, and many people have cursed Campro and Proton for this shortcoming.
When CPS came out, it featured a variable intake manifold (VIM), which is essentially a mechanism that regulates air intake speed depending on the RPM. When below 4k RPM, the air going into the intake manifold is slower, whereas beyond 4k RPM, the air is allowed to enter the manifold at a higher speed. This mechanism overcame the torque dip and introduced a much smoother torque curve to the Campro engine. Don't ask me how it did that, I don't know the exact details as to how the VIM eliminated the torque dip.
The IAFM functions the same way as the VIM, the only difference is that the VIM is electronically controlled by the ECU, whereas the IAFM is mechanically controlled by intake vacuum. If you removed the IAFM or your IAFM malfunctions, you will notice that your car is underpowered at the 2k-3k RPM.
thanks

Added on November 4, 2012, 11:49 pmjust now i read somewhere on the net there is a guy have problem where his fuel bar will not full even he pump full.
then the mechanic replace something.
forget that website already.
because i remember last week when i was in ipoh, i refuel until full then one bar left not full on the meter
Added on November 4, 2012, 11:52 pmfound it
QUOTE
If the modulator does not cause the noise, what is it about?
Rather than making noise, it is actually controls the fuel meter. For Proton Persona owner, do you notice that the fuel meter never show FULL even though you have a full tank? Tell the mechanic during your next service and they will replace for you. Make sure your warranty is not end and bring along your car grant (photo copy will do). The modulator cost more than RM400 in the market, wao..
http://putrapermai.org/2009/07/02/proton-iafm-engine/This post has been edited by asrul: Nov 4 2012, 11:53 PM