Every idling symptom described, someone please help....

Newbie Joined: 23 Feb 2005 Posts: 1

Renault megane 1.6e 1998 Hatch

Half the time when i drop the clutch the engine will cut out.
The other half it will dip where it almost cuts out and then recover but will not be stable.

Idle control valve & Throttle body has been cleaned out thoroughly.

The air temp sensor on the inlet tube has been checked, it doesnt look dirty at all. Map Pipe is clean. The sensor looks ok itself.

Driving in low revs very sensibly in low gears and the car will not stall. When i push it though the car will cut out. The revs will just drop as if i've turned the engine off. (general behaviour, sometimes it CAN take high revs but not often).

Popping to a scrapyard at the weekend back in Surrey.

I was thinking of grabbing a new map sensor, new air temp sensor, and the entire throttle body (which includes the Idle control valve and the Throttle position sensor).

My speedo is also behaving erratically although im not that bothered but maybe is has some kind of effect on the car?

When the speedo drops to zero (if im doing 80 for example) then the car will drag, then the speedo will jump up and the car will get a boost. Not sure which causes which!

Anyone with any information, tips clues etc would be much appreciated, local garages dont seem too interested in helping!

Forum Moderator Joined: 18 Feb 2004 Posts: 7432

have a look at the road speed sensor, clean or replace if necessary.

Forum Moderator Joined: 02 Mar 2004 Posts: 19978

sort out the earths on the back of the engine, they corrode easily.

I have had to sort out a few by chopping mthe wires and re-terminating the ring terminals. They are held on by T30 bolts into the engine just above the sump. This is where the whole set up is earthed, they can cuase cutting out, erroneous info to the ECU and can make the speedo and the rev counter behave funny.

Also due to the crap design of the idle control plunger it may just need replaced, its not very good and doesn't last. A thorough clean can help it even solve the problem for a while but they can and do just pack in.

I would check the earths first, then look at the road speed sensor which is on the gearbox, its an electrical sender and it can get very oil contaminated.

When the speedo cuts out it may be due to a faulty earth or simply causing the ECU to decide the car is just revving with no load thus the drop in power.