Engine revs dive down upon slowing down.

Hi its Nigel  E3 djet .I have the engine C/O set to around 3.5 % and the idle speed around 980 RPM .Every time the car slow,s down the rev counter drops to around 200/250 rpm then comes back up to normal. How can i stop the revs going so far down ,or is this normal ? ( My previous no starting problem turned out to be a small wire had come loose which in turned cut out the main relay.

I thought for a minute id have a answer to my post !

An auto electrician found the loose wire on a contact block which was on my top servo of two.This was causing the main relay to fail. Nothing else to say except it fixed my car.

I thought by now someone would know the answer ????

Hi Nigel,
the question is....?

I can't believe the engine really slows down to 250rpm.
I don't know one single car or bike engine that is able to run with such low rews.

Did you check this with another instrument?

Another idea: Does the engine has a dash-pot installed at the throttle?
Maybe this could prevent the TPS from switching the idle contact as long the throttle isn't fully closed.

Regards
Norbert

Hi Norbert,
Thanks for your reply.What i mean is when slowing down the revs dive down to around 250 rpm but go straight back up to normal.