Pulsating tick-over
 

Hi Guys,

My '99 2.5lt 10v V70 was last used Tuesday 28th January, and then it was a short move of the car of 50 yards or so to park the car after some road works had been completed. I went to use the car Yesterday (Friday 31st January) and I got one kick on starting and then the car failed to start. It would turn, and I could smell petrol but no ignition. I left the car for 20-30 minutes and tried again, and after a rough start (as if mis-fire on one cylinder) it cleared and licked over OK and revved to the red line no problem.

I went out and tried starting the car again this morning and its started OK, but it pulses on tickover - between 1700 - 1300 RPM. I can cold the car at 2000 RPM or above with no issue, take my foot off the pedal and the revs fall to 1300 and then pulse again. Turning off and re-starting it does exactly the same.

The care is still cold so I don't know if that's the issue, but it has never fast revved on a cold start in the 13 years I've owned the car. Anyone have any ideas (crank case position sensor ????)

It could be something as simple as damp in the electrics. If I were you I'd give it a good run, get it up to working temperature, dry it out, and then see what you've got. Eliminate the simple things first.

Dave.. :thumbs_up:

From my personal experience my instinctive response is the much debated Lawn Mower Syndrome, which gets its name from cases where people have a car which runs fine on Friday coming home from work but won't fire up on Monday to go to work, when the situation is dissected it comes out that it was OK Friday, and oh I moved it out of the garage on Sunday to get to the lawn mower. Volvo 850 and V70 engines often don't like being started and stopped almost straight away there's a long debate on why but for the moment I'd suggest if it will start either let it run until the engine is thoroughly hot and/or take it for a long run, Let it go cold then see what it does, but if you start it make sure it gets up to temperature before you stop it.

Well you guys know your stuff - I've just taken it for a short drive (2m) to get petrol. It was pulsing even whilst the engine was warming up... pulled in to the petrol station and the revs dropped to normal steady idle.

I guess it was just damp somewhere in some sensor given the rain we've had over the past few days, and the fact that its last run was so short. I'll let the car cool and re-start it again, and as suggested, let it warm up before turning it off.

Well its a long time since I've had a petrol car Malcolm, but when I look back at the times I did and had problems, nine times out of ten it was damp.

I do hope it was just that though, there's nothing more disconcerting than wondering if your cars going to start.. and keep running.

Let us know if it definitely was that, as all these little bits of information could well help someone else down the line..

Dave.. :thumbs_up:

I guess we'll never get to the bottom of it... Just went out and restarted the car and it's fine, ticking over nice and steady around the 900-1000 rpm mark.

Never had issues with damp before on this car - my old Viva was constantly smelling of DW40 because the HT leads were covered in it :)

I'll keep an eye on things, but I think its all good now - thanks for the suggestions though... I was thinking the worst yesterday !!

Chances are you won't get to the bottom of it, damp and electrics (if that's what it was) are strange bed fellows. I have a problem with my alarm system when its damp. Get a dry warm period and its as right as reign.

I'm glad the car is running well now though.

Dave.. :thumbs_up:

Having scrapped an 850 with starting problems then had the V70 do the same (once) I thought a lot about the cause, the only change I've made to the car is to use a 0w40 oil rather than a 10w, on the basis it should flow a little better when cold. I still don't know if that's truly effective though, I quite often think I should try the car with a very short run (100yds) and see if it starts OK next day, but then I think I haven't got time for that hassle.

Etm..... If it has one?

ETM ?????

The car is due to be serviced shortly (been sourcing parts including fuel filter as it's been a while since that was changed), so its not as if this happened after using different oil or plugs etc.

I'll keep an eye on things and see how things go... hopefully once the weather gets warmer there will be less chance of a re-occurrence