What is a purge canister as found near an injection fuel tank and what does it do?
Is it really needed or can it be done away with?

[Edited on 4/6/13 by Talon Motorsport]

It's an activated carbon filled canister that absorbs fuel vapors from the tank rather than venting to atmosphere. These are then released into the inlet manifold under certain running conditions via an ECU controlled valve.

Yes, you can loose it on the kit.

I never installed this on my mx5 engined kit. The diagnostics shows a fault, but seems to run fine without it (although I haven't driven out the workshop yet).

You should be able to get rid of the fault cod by fitting just the solenoid valve. Tuck it away somewhere in the loom. Easy if it's in the pipework but a bit trickier if it's integral to the canister (don't know which it is on the MX5).

I should have said that this for a 2.9 V6 Cologne engine which I'm having trouble make idle, so if it needs the canister and EVAP valve to sort it I should'nt have thrown it away with the Granny tank.
There's a reason I don't have have any thing to with engines or their electrics.....

[Edited on 5/6/13 by Talon Motorsport]

The canister and solenoid valve should not be needed to idle properly. However, since the solenoid valve is plumbed into the vacuum side of the throttle, if it's been removed and the spare pipes haven't been blocked you'll have an air leak. Since the old V6 uses an air flow meter, any leaks here will be unmetered and cause poor running.

Like Mike says, the purge valve/canister shouldn't effect the idle. It purges (from memory) on overrun. It'd be shut at idle so no different to it not being there, as long as you've blanked the pipes off.

V6 Cologne EFI used to have problems with the idle valve sticking due to oily deposits in it and similar on the throttle. Clean both out with carb cleaner if they're dirty.

I'll give the idle and throttle body a strip and clean, I should have done that that before I started it but that first turn off the key was just too temping.... it might be why it runs lumpier than school custard and banana slices. Mind you being sat in the corner of the work shop for 6 months may not have done it any favours either so new plugs,leads,dizzy .....

On MX5's remove the canister, connect the inlet and outlet pipes together using some of the pipework you've just removed.
Disconnect the solenoid wiring by removing, and taping up the connector.
Standard practise, been done many times and AFAIK no major problems or faults result.
HTH.
Cheers, Pewe10

Removed the charcoal canister from my tin top to lose the 1kg it weighed!

The eec-iv run's fine with out the evap and egr but the ecu will log the code's. As said watch for air leaks. To remove the code of the evap you should be able to simulate a load with a resistor.