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Weird symptoms

Question : I DRIVE a 1.3-litre 5-speed Myvi (manual) with just over 3,000km on it.

When new it was not smooth, but after the first 1,000km service, the engine acquired a certain abruptness.

It happened when the car was allowed to slow down with the gear engaged.

Instead of slowing gradually, its speed would dip suddenly at certain engine speeds.

The feeling was the same as an automatic when it downshifted, except that mine is a manual!

I call it "engine drag" because it felt just like engine braking when downshifting.

The engine speeds at which it happened were around 1,800-2,100rpm and 1,500rpm.

My usual service workshop said it was the ECU and nothing could be done about it.

The second workshop replaced the ECU but the car displayed the same behaviour.

I was told that all Myvis are like that.

A third workshop said that it was because of the air-cond compressor cut-off.

If I leave the air-cond on high so that the compressor is always on, the problem would. go away.

The other alternative is to switch off the air-cond.

Well, the second option is not really an option, but the first didn't really work.

Anyway, even the second option did not work very well either; some drag still could be felt even with the air-cond off, even though less.

Well, are all Myvis like that? Or what is wrong, and what can I do about it?

Answer : I am not too sure about what you are talking about but I suspect that what is happening is that the aircond compressor is cutting in and .this is causing drag on the engine and a subsequent feeling that the car is slowing down through engine braking.

This happens with low capacity cars simply because the engine power is quite low at low engine speeds and the load of the compressor causes a substantial drop in the engine speed.

Actually, the EFI system has an idle compensating valve that is supposed to increase the air-fuel mixture when the compressor cuts in and you should not notice the drag.

I suggest that you visit a Perodua service workshop rather than an outside workshop and get them to have a look at the problem.


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