S40 1999 2.0 petrol auto: revs drop soon after starting

rannydoscoe · Mar 14th, 2022, 14:18

Hi, first post. I've had this car incident free for about six years and have lurked when trying to solve litte problems with it! At about 95,000 miles now.

Was wondering if anyone has experience with my issue. Recently it's started dropping revs on acceleration, mainly after it hasn't run for a few hours. Generally this is first thing in the morning. Although can be in the afternoon if I'm not out in the morning.

It'll start and pull away OK and run fine for 30 seconds or so (I live at the top of a hill). After this, when I accelerate (say after slowing for a speed bump), the revs drop very low for a good second or two, it hesitates and then it kicks in and goes. Sometimes I'll get some black smoke from the exhaust.

If I sit and lights and stop in this time frame it'll behave the same, so hesitate for a couple of seconds while I'm on the gas, then go. After a couple of minutes of this behaviour it'll go completely back to normal (runs great!) and I won't have any issues for the rest of the day.

On a really cold day recently it completely cut out while I was driving which was a bit disconcerting, had to leave it a couple of minutes then it did start eventually.

It's recently had new plugs, oil change and filters. It was behaving a bit badly before this, juddery on acceleration. Have had it with the local mechanic but they can't find anything wrong, no codes or anything. They cleaned the throttle body and idle control valve but nothing has changed really.

Anyone have any experience with this type of thing?

Cheers!

rannydoscoe · May 18th, 2022, 10:55

Coolant temperature sensor replaced, and back to normal again!

Mar 14th, 2022, 14:18	#1
rannydoscoe New Member Last Online: May 22nd, 2023 10:25 Join Date: Dec 2019 Location: Manchester	S40 1999 2.0 petrol auto: revs drop soon after starting Hi, first post. I've had this car incident free for about six years and have lurked when trying to solve litte problems with it! At about 95,000 miles now. Was wondering if anyone has experience with my issue. Recently it's started dropping revs on acceleration, mainly after it hasn't run for a few hours. Generally this is first thing in the morning. Although can be in the afternoon if I'm not out in the morning. It'll start and pull away OK and run fine for 30 seconds or so (I live at the top of a hill). After this, when I accelerate (say after slowing for a speed bump), the revs drop very low for a good second or two, it hesitates and then it kicks in and goes. Sometimes I'll get some black smoke from the exhaust. If I sit and lights and stop in this time frame it'll behave the same, so hesitate for a couple of seconds while I'm on the gas, then go. After a couple of minutes of this behaviour it'll go completely back to normal (runs great!) and I won't have any issues for the rest of the day. On a really cold day recently it completely cut out while I was driving which was a bit disconcerting, had to leave it a couple of minutes then it did start eventually. It's recently had new plugs, oil change and filters. It was behaving a bit badly before this, juddery on acceleration. Have had it with the local mechanic but they can't find anything wrong, no codes or anything. They cleaned the throttle body and idle control valve but nothing has changed really. Anyone have any experience with this type of thing? Cheers!

May 18th, 2022, 10:55	#2
rannydoscoe New Member Last Online: May 22nd, 2023 10:25 Join Date: Dec 2019 Location: Manchester	Coolant temperature sensor replaced, and back to normal again!

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