low speed lumpiness

[Hood38]

I would like to know if anyone else has suffered this problem - anything under 2000rpm the S2 will not run smoothly. Above this she is as sweet as anything and the higher up the rev range the better.
Before I get the wave of 'throttle pot' replies I did change that 2 weeks ago and recently disconnected it again to make sure it was not a duff one. With the pot unplugged I get a worse version of the same problem. Put new plugs in recently too.
Is there any way the idle valve could affect performance in the lower rev range i.e. above tickover but below 2k revs? Could any of the other sensors be to blame?

[GreenV8S]

Not the only possible cause, but if there was an air leak in the inlet manifold, it would cause more trouble at light throttle?

[andyf007]

Has it had the cam changed? Fast road cams are awful below 2-3K.

Andy

[Hood38]

It does have a Kent performance cam and I accept there should be some lumpiness in tickover and low revs but sureley not this bad. The car won't travel at 30 or 40 mph without hopping. Who would fit a part that did this to a car?

[andyf007]

Hood38 said:

It does have a Kent performance cam and I accept there should be some lumpiness in tickover and low revs but sureley not this bad. The car won't travel at 30 or 40 mph without hopping. Who would fit a part that did this to a car?

Do you really want me to answer that!

Do you know which profile cam it is? If they fitted a "road race" cam and not the "fast road" cam, then you will easily get your current performance. These cams are meant for racing, ie. staying above 3K for the duration, they are total pants for normal use. Great if you only use it for track days, I suppose.

Andy

[Hood38]

I have written to the previous owner who had it fitted to find out as I probably need to own up on the insurance too but no reply to date. I have to admit that above 3k rpm it is fantastic but like everyone else I have to spend time in traffic and it is like a caged animal.