Flat spot below 3,000 rpm

low

覆盖范围已复核

可以继续驾驶。方便时再维修。

涉及车型年份: 2004-2008

症状

Car feels weak pulling away from a standstill
Needs a downshift or more revs to climb a hill
Noticeable surge as the engine passes 3,000 rpm
Automatic hunts between gears at part throttle

原因

The fixed-cam S4PH makes its torque at 4,000 rpm, and there is a well-documented dip below 3,000 rpm. This is how the engine was built, not a fault that appeared with age. Proton addressed it in the 2008 facelift with the IAFM and CPS engines, which is why later Gen-2s feel stronger in town.

解决方案

Adjust how you drive rather than chasing a repair. Rev it a little more, use the manual's gearbox instead of lugging it, and do not expect a 1.6 to pull from 1,500 rpm. If the car has become noticeably flatter than it used to be, ask a workshop to check the basics first: a dirty air filter, tired spark plugs or a failing ignition component can make a normal flat spot much worse.

预估费用:~RM 0(免费)

未注明计价方式 · 未注明日期

Do not buy an engine additive for this. The dip is in the cam timing and the intake design, not in a bottle.

The useful test is whether the car feels the same as other Gen-2s. Drive a second one if you can. If yours is much flatter, that is a maintenance problem wearing the engine’s normal character, and the cheap service items are the place to start.

For a manual, the fix is driving style: stay above 2,500 rpm on a hill and accept the extra noise. For the automatic, the gearbox is already trying to keep the revs up, which is why it can feel busy at part throttle.

Cost: nothing to fix. A service that restores lost performance is priced on the parts pages, and anything beyond that is a diagnosis, not a tune.

社区笔记

The torque dip is the standard complaint in Gen-2 owner threads and in the paultan.org 3 March 2008 facelift report, which gives 139 Nm at 3,000 rpm for the IAFM engine against 128 Nm for the original CamPro.