Battery changed now it won't idle

[TVR keith]

Help please! Had the battery out for a couple of weeks whilst I changed it and did a few bits underneath, now it won't idle.( I haven't done any work on the engine except clean the plugs & it was idling fine before the battery died)
Starts up Ok, after a few minutes with no throttle it revs up and down on its own.
Stop the engine for a minute and restart and it's fine.
Do I need to disconnect the ecu for a few mins and reconnect, if so is this the connection to the ecu by the battery or just the multiplug on top of the airflow meter?
I seem to remember being told about some proceedure about resetting the stepper motor, can't remember how this is done?
it's a nice day so I'd really like to go out for a blast, so if someone could enlighten me it would be much appreciated

[Cider Andy]

Yes, you can try disconnecting the ECU for a minute, using the large multiconnector on top of the unit (in the footwell, as you thought).

A search in this forum on 'stepper motor' will return many results, some describing how to clean it, but a couple will describe how to disconnect it with the engine at idle.

[chim666]

While you're down there with the battery exposed (!), I'd re-seat the two silver relays (the ones hanging off the end of their cables). They have been known to cause erratic starting/running. Worth a shot!

Edited by chim666 on Thursday 30th November 12:03

[TVR keith]

Well I took it out anyway, idling a pain at first, but after 200 miles today, and a tankfull (nearly gone) of V power it's running a treat.
Perhaps I ought to try it tomorrow.......