Engine "hunting"

[MRC89]

Firstly, the term "hunting" is borrowed from my dad, unsure if it's the right word for the problem.

So over the last few hundred miles my engine has starting shuddering in the low rev range, this is most noticeable on Idle in neutral, every several seconds the car will rattle slightly and the rev needle moves slightly on it's own. It doesn't happen all the time, but more often that not.

It also happens when crawling through traffic in first and second gears, with the low speeds involved in traffic crawling, the revs are usually between 1,000 and 1,500. From time to time the car will continue to rattle as it does in neutral, however this affects the speed of the car as it's actually in gear! Even if I keep my foot steady as a rock the car will speed up then slow down in shudders, which not only is uncomfortable but makes me look a bit stupid!

The car is approaching 11,000 miles now, and I intend to bring it up at it's 12,000 mile service, but is there anything I can be checking in the mean time?

Thanks

[kabz77]

Good Morning,

I might be totally wrong here but could it be anything to do with your mass air sensor?

Kab

[2011fiesta]

My dad had this with his old corsa. The hunting got so bad that the engine would cut out even when in neutral or in gear with the clutch fully depressed.

We were told it was the build up of carbon from the E.G.R(?) valve which has something to do with recylcing the exhaust gasses back into the system for an improved emissions rating/output.

We were also told that the car should of been giving "a good blast" down the motorway more often to clear out the cr*p, and that for every other tank of diesel we put in, we should have added some additive. (My dads a driving instructor so the car didn't get much motorway exercise for being a 1.7 turbo diesel).

A change of air filter and entire bottles of additive improved the hunting but this quick fix never lasted longer than a week.

When various parts and tubes (I'm no mechanic as you can see) were removed they were completely blocked with a solid build up of carbon. We went through months of mehanics and dealers trying different things but the car was still a nightmare - (our local Vauxall dealer even said after a week of having the car if you want just take the car back and we'll forget about the bill as they couldn't solve it). I'm not trying to worry you, this was of course an extreme case compared with yours - just thought I'd share this experience as it all started with slight hunting .

You should try to get this seen to mate.

[briggsy]

i have seen this before in my GF's car with Aircon that was out of FreeOn. it was only notasable at idle or low revs. Not sure this is the problem but could be.

[MRC89]

My dad had this with his old corsa. The hunting got so bad that the engine would cut out even when in neutral or in gear with the clutch fully depressed.

We were told it was the build up of carbon from the E.G.R(?) valve which has something to do with recylcing the exhaust gasses back into the system for an improved emissions rating/output.

We were also told that the car should of been giving "a good blast" down the motorway more often to clear out the cr*p, and that for every other tank of diesel we put in, we should have added some additive. (My dads a driving instructor so the car didn't get much motorway exercise for being a 1.7 turbo diesel).

A change of air filter and entire bottles of additive improved the hunting but this quick fix never lasted longer than a week.

When various parts and tubes (I'm no mechanic as you can see) were removed they were completely blocked with a solid build up of carbon. We went through months of mehanics and dealers trying different things but the car was still a nightmare - (our local Vauxall dealer even said after a week of having the car if you want just take the car back and we'll forget about the bill as they couldn't solve it). I'm not trying to worry you, this was of course an extreme case compared with yours - just thought I'd share this experience as it all started with slight hunting .

You should try to get this seen to mate.

Well I regularly give the car "a good blast" but I don't push it too hard. I've heard from a friend that it could be anything that affects the petrol or air levels inside the engine, which if true, could be one of a hundred things I imagine. Thanks for the heads up anyway, I think I'll get the service booked early and hope they can find it and fix it.

And thanks briggsy, the car does it with and without air con. As it's developed over the winter, I've barely had the air con on

[Nay ZS]

My car has also starting doing something simalar or the same to this. Again it has developed over the winter.

When you driving at town speeds I feel a slight hesistations and just last week it had a big shudder/loss of power for about a second or two.

When im in traffic you can really notice it not idling smoothly as it does its shudder thing maybe once every 20 seconds or so, it almost feels like the car behind has rolled into the back of you. Very slight but a weird feeling.

Car is due for a service soon so I will also be getting this checked out.

[MRC89]

Sorry to bring up an old thread, recently the hunting became regular, every time I was sat still the whole car would shudder and when I tried to drive slowly through traffic it would constantly (and uncomfortably) affect the speed. Today me and my dad took out the spark plugs and gave them a good clean, and now it sits perfectly at idle, and only occasionally, and gently shudders, This might be normal, but it's been a massive improvement. Thanks to everyone who suggested the above causes, it could of been any of them really!

[2011fiesta]

Sorry to bring up an old thread, recently the hunting became regular, every time I was sat still the whole car would shudder and when I tried to drive slowly through traffic it would constantly (and uncomfortably) affect the speed. Today me and my dad took out the spark plugs and gave them a good clean, and now it sits perfectly at idle, and only occasionally, and gently shudders, This might be normal, but it's been a massive improvement. Thanks to everyone who suggested the above causes, it could of been any of them really!

Glad the cars okay Mark, or at least much better. Must be a relief after my horror story lol

[benjii]

Sorry to bring up an old thread, recently the hunting became regular, every time I was sat still the whole car would shudder and when I tried to drive slowly through traffic it would constantly (and uncomfortably) affect the speed. Today me and my dad took out the spark plugs and gave them a good clean, and now it sits perfectly at idle, and only occasionally, and gently shudders, This might be normal, but it's been a massive improvement. Thanks to everyone who suggested the above causes, it could of been any of them really!

i had the same problem with my zs i took it to my mates garage and he said due to the crap design of the water pipe or somthing due to the water jets on the point somtimes they leak water on to the spark plugs what cause the shakes as it leads to a miss fire he said he had a fair few focus doing the same we changed the spark plugs and put a new water pipe on never had the problem since

[MRC89]

The spark plugs were also out of alignment, I only found this out today haha!

Maybe the previous owner had taken them out and not replaced them properly, or someone's had a fiddle.

But they were set to 2-3mm gaps (all different) They were taken out and reset to a 1mm gap.

This is probably the main cause for improvement, I didn't realise my dad had done this cause I was asleep!