200tdi revving at idle

Hi all, annoying problem with my 200tdi at the moment-

When up to operating temp, (just under the 1/2 mark on the gauge) the idle speed plays about.
It's totally random, sometimes it sits as it always used to at 800ish rpm. More often than not however, it starts revving up to 1100/1200 rpm. The throttle is returning to its stop properly.
Even more irritating is the fact it tries to stall when changing down, approaching a roundabout for example- it doesn't make sense.
Before this problem, it always used to settle at 850rpm, either at natural idle or when changing down and dipping the clutch.

I've changed the air and fuel filters and it gets fresh oil and filter every 5k. There are no air/ fuel leaks going from the filter to the pump. Otherwise it runs fine. Always averages 29mpg.
Now suspect the injection pump but I have no experience of these Bosch pumps. Anyone know what I should be checking?

Thanks

Sounds more like air getting into the fuel system, perhaps a vacuum leak at the fuel pick up pipe which is common ...

it will be something that has been disturbed when the service items were done...

Check the filter it may be faulty and if it has a sedimenter on the chassis

even the lift pump may be on its way out

Check all the pipes and connections.

It will be something simple.

I agree Dippy, must be something like that.. but I can't find any air leaks at all am living with it at the moment, doesn't seem to be getting any worse- just irritating. Only happens when the temperature is in the middle of the gauge, which isn't happening a lot at the moment

I've been living with the very same symptoms with my 200tdi for the past few months. Unfortunately for me, I find myself in the tropics, so getting up to that temperature where it acts that way comes not so long after start up.... I checked just about everything but the problem wouldn't go away. I put it on here and there wasn't much said about it so I just lived with it as it is. Mine is coupled to an autobox, and I've noticed that whenever the rpm would spike, I could get it to settle back at normal speed by momentarily shifting into drive and back into neutral or by turning the AC on for a few seconds.
Best of luck mate, and let's hope we find a solution soon.

My 200 idles at random too. Not looked into why yet, cos I have had bigger issues.

I'll keep at it. Sounds like it's probably a common thing but is accepted as 'ok' because the vehicles are very old now.
I don't mind the problem as such, it's just if it's a symptom of something more serious- then I'd like to find out what's up.
Typically, mine's been perfect today :smash:

David_Cooper said:

I agree Dippy, must be something like that.. but I can't find any air leaks at all am living with it at the moment, doesn't seem to be getting any worse- just irritating. Only happens when the temperature is in the middle of the gauge, which isn't happening a lot at the moment

Click to expand...

Get yourself some clear pipe same ID as the fuel pipe -

Put it in different positions in the fuel line, so you can see any bubbles created / sucked in - to narrow down WHERE it's coming from

then we have to work out why ...

Having had a rummage round the threads - isn't the search facility wonderful

I have found this:
http://www.landyzone.co.uk/lz/f7/200tdi-300tdi-lumpy-idle-smoke-fixed-153190.html

and as I don't know how old your vehicles are and whether they have 'idle control valves' or 'throttle position sensors' - which can cause the problems ...

I did read that thread you found Dippy, it's very interesting and I think I will replace my pipe with clear. That chap's problem was slightly different to mine though, I have no misfire or smoke, just a raised idle. I might look at a set of new injectors, but at around £400, I may have to live with the problem