Uneven idling?
 

My MY99 RB5 WR has began to idle extremely unevenly....

It seems to average at around 800rpm, but can drop as low as 450, before going over 1k, then dropping again.....

It actually seems as though it is going to stall, but doesn't.

The car has a K&N induction kit fitted.

I appreciate that without seeing it, it may be hard to diagnose, but does anyone have any suggestions as to what to check first?

MAF?

Cheers

Talisman,
If there are no air leaks in your pipe work it will be your maff sensor its just happened to a mates car and thats what the problem was.

Might be an air leak but most likely the MAF or 02 sensor...

A couple of quick tests for the MAF and lambda...

1. With engine warm and idling, pop bonnet and disconnect MAF sensor. If engine stalls, the MAF might be OK. If the engine continues to idle as it did with the MAF connected, there's a good chance the MAF is failing, and the ECU has "learnt" its way round (see 2).

2. Perform an ECU reset. If the CEL flashes all clear pretty much instantly, your lambda's probably OK. If it takes ages to flash all clear (or flashes the lambda fault code... ;)), the lambda might be on its way. After you've disconnected the black and green connectors, go for a drive about, and if it drives absolutely terribly to begin with, but gradually improves over time, that's another indication of pending MAF failure...