2 issues, are they related and what might be the cause?

Technical Area Engine, Transmission, Exhaust etc
1

I recently picked up my 1999 Mk2 1.8 ‘Sport’ edition and love it very much.

It runs well apart from two issues which I think may be related.

Firstly, it is very slow to turn over, difficult to get going. Sometimes it takes 2 or 3 attempts to get it started up, especially when it’s colder. This is meaning I have less confidence in taking it places in case it doesn’t start at all and I get stuck!

Secondly, there is an engine jerking or hesitance, at around 5000rpm in any gear from what I can tell. It’s more of an aggressive jerking/jolt when under heavy load (up hill, foot flat to the floor), and isn’t as easily triggered if I very gently take it up to 5000rpm.

My first thought (and easiest thing) was spark plugs and leads so I changed them.

To my disappointment it made little to no difference to these issues. Perhaps the jolting engine was slightly less severe but maybe I’m imaging it.

Next thoughts are fuel filter, air intake (has an ebay after market one on it but don’t see how this would effect the start up and engine at such a specific rpm), clutch (although I don’t think it feels like a clutch slip, more like a misfire) and I saw something in another thread about the crankshaft position sensor.

Other info: recently had new belts all round, but belts have quite a noticeable whining noise. Fuel filter hasn’t been changed in a while. I also chucked a different coil pack in it when changing the plugs and leads, a second hand one as part of mine snapped due to a seized lead connection.

Any thoughts on the matter would be appreciated. Would love to get my confidence up with the car so I can enjoy driving it but at the minute I’m not enjoying it so much for the above reasons. Thanks!

2

Slow cranking is probably the battery, could be connections.

I wonder if the jolt is fuel starvation, which could be down to your fuel filter, so may be worth changing it.

1 Like
3

I had some issues with a Yuasa battery in my NB, which, although reading in the high 12 volts, would turn the car over very sluggishly if left for more than a couple of days. I replaced it with a Panasonic battery, as originally fitted, and the car starts first time, every time now with no hint of hesitancy, even with the cold weather we’ve had this week.

The Panasonic battery was quite a bit more than other alternatives but I’m more than happy to have forked out the extra for the peace of mind.

1 Like
4

It does have a cheapo battery in it from what I can tell. I’ll get some advice from a battery shop and see if they think it’s worth upgrading it. Thanks for the comment

5

Sounds as if the battery might be feeble but that wouldn’t account for the misfire/jerking.

Check the battery earth on the powerplant frame. On my old car (also a '99) it had all but dropped off from corrosion.

TBH mine had so many intermittent (so hard to fix) faults of this kind I got rid in the end.

6

Well hopefully I can nip it in the bud but that might be wishful thinking

7

New crank shaft sensor fixed this issue and the hesitation at high load/revs, thanks for all the advice, drives like a dream now :slight_smile:

2 Likes