Smooth running?

[James_G]

I am now beginnning to concentrate on the smaller stuff on my S2 and so have turned my attention to optimising the engine. When I bought it in Jan it got a decent service including new spark plugs, and under wide throttle openings it pulls really cleanly and smoothly but when coasting down and under light throttle openings it doesn't run smoothly and there's a subtle juddering, a bit like a fuelling issue. Not a deal breaker I grant you, but it makes it feel a bit old and it can't be doing the gearbox any favours.

While doing another job I took the MAF off (barn door?) and that looked all clean inside, but beyond that I haven't done any further investigation, as I thought I would ask what the likely culprits are. So, with the weekend coming up, what should I look for first?

Oh and I am using Shell fuel, not that I think it would make much difference from supermarkets, but it's convenient. And you get Airmiles.[]

Thanks

 

[Diver944]

My guess would be the track inside the AFM or maybe the Throttle Position switch.

My Turbo was a bit like that before it had it's new engine and they were one of the many things replaced (so that doesn't narrow it down much - sorry [8|])

 

[pmc_3]

My 2.5 is very similar, just doesnt feel smooth at less than half throttle below 2.5-3k. Pulls nicely at full throttle all the way through the rev range though

 

[swright]

Check your drive shaft bolts aint coming loose!!! Im not kidding. I had this problem and it got worse right up to the point when one detached itself from the gearbox!! See my thread about it.

I could well be wrong but id definatly check them just to be sure.

Stu

 

[zcacogp]

James,

Can't comment on the suggestions already made, but my S2 is noticably smoother after I started to use it a decent amount. Starting her up once a week for a short run won't do her any favours.

Other points are regular servicing with good oil and new plugs. What about the HT leads and dizzy cap? Pricey things, but ropey electrics can make an engine run more roughly.

I also find that higher-octane fuel helps (and the increased MPG makes it slightly cheaper than the 95-grade stuff.) When you say you are using the Shell fuel, do you mean the Optimax (or whatever it is called now)?


Oli.

 

[James_G]

Thanks for the suggestions chaps. I checked the drive shaft bolts when I was under the car recently and they are all in situ, and if they are like any of the other bolts on my car, they won't be coming off easily. []

Oli, the car has Beru HT leads and they look recent, but I have nothing to substantiate that. Dizzy cap/rotor were things I was going to check over the weekend as I had similar symptoms years ago on a Fiat when some coil packs were breaking down under load. But there's been some talk elesewhere of dodgy connections on the throttle position sensor - so I'll check that too.

As for use, I tend to take it out of the garage for a weekend and enjoy myself such that I then use it all week, and then clean and dry and then back in the garage. Plus I've done a track day recently and some regualr trips back to Wilts so it's almost never ever short journeys. Not using V-Power in the S2 yet, as I can't cope with the financial prospect that both of my cars will run better on it[].