[ahd91]

I've recently been having problems with a sudden and severe drop in RPM while driving or when at a standstill.

The car loses 500-1000 RPM without any warning, maybe once a day.

This happens sometimes at idle with no issues, but the car has stalled a couple of times when at lights. It can also happen while driving up to around 30-40, resulting in a sudden jerk as the car slows, almost like driving over a patch of ice, but it's never happened beyond that speed.

Another issue which may or may not be related is that on a couple of occasions the car hasn't started first time when low-ish on fuel (light not actually on yet), and the light comes on very quickly even after putting in £20. This happens even when the car is recording around 27mpg.

Any ideas?

 

[bartwins]

It may be that your fuel pump is giving up. It would be worth hooking up a code reader (ELM 327 from ebay, about £15) Even if the car is not showing a fault light, driving with a code reader connected may show a pending fault if the car stumbles.

Or it could be the DI unit, getting a cheap used genuine one would be a good investment anyway. Also check all the rubber pipes under the bonnet, make sure they are connected and in good condition.

 

[ahd91]

The fuel pump sounds like it's running fine, but I'll get a code reader to check it out.

I've now realised that the no start problem has all of the signs of the crank position sensor going - it only ever happens within an hour of driving the car, and the RPM needle does not move at all. Could this also be the culprit for the stuttering problem? Doesn't seem like it.

Other suggestions have been the throttle body?

 

[bartwins]

I have had a misfire with a faulty cps so its possible, the car started perfectly but misfired when under way.

If the tacho is not moving when you're cranking the car it would point to the cps.