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I have a Volvo S40 (diesel) and sometimes I have a problem around ~2,000 RPM: it is something like a limp (or you could say that the car hiccups)

Strangely, when my brother drives the car, he does not have this problem, it only happens when I drive.

Also, could you tell me at what RPM should I drive? I usually drive at around 2,000 (but, I am used to a gas engine, I've only recently started driving a diesel).

It has manual transmission

EDIT: last time when this happened, I went to over 3x1000 t/m and it solved the problem for a time.

  • It would be useful to know if your car has a manual or automatic transmission. – dlu Sep 5 '16 at 11:56
  • Also, the term "limp" may cause some confusion – it often refers to a problem/symptom of relatively long duration (it could last the whole drive). I think what you're describing is brief, momentary thing (that's what I get from hiccup). So I'm wondering if the word "stumble" seems to you like it would fit your symptoms? – dlu Sep 5 '16 at 11:58
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Looking at the Wikipedia entry for the Volvo D5 engine, it looks like the best torque band starts around 2,000 RPM. So, what could be happening is that you're upshifting (e.g., going from 3rd to 4th gear) too early and the engine doesn't quite have enough torque to make the transition smoothly – if you remember learning to drive a manual, you may recall some "bucking" as you learned to time your shifts and modulate the clutch smoothly.

That is also consistent with the problem "going away" when you shifted at 3,000.

In terms of what engine speed to drive at, that depends…

  • At lower speeds the engine will be quieter and will consume less fuel, but you will need to be more careful to match the gear to the engine speed.

  • At higher speeds it will be noisier, but also more forgiving of gear choice.

  • Diesels, in general, have more torque and the torque is available at lower RPM. According to the Wikipedia article, there are quite a few variants on this engine, but in broad terms the torque range is from about 1,500 to 3,000 RPM. Those would be good speeds to drive.

My last piece of advice would be to observe your brother as he drives. Notice what speeds he shifts at, the issue you're noticing is very likely related to driving technique.

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