Welcome to our resource for MG Car Information.



MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGF Technical - Idle Problem

Iv'e got a 98R VVC. This weekend it has suddenly started playing up a little. When I started it in the morning the engine was overidling and running really lumpy. I thought this may be a problem with damp and cold but when the engine warmed up it still ran too quick at idle (about 1300 revs) and oscialated around this level by about +-200rpm. It then also started cutting out altogether when coming down from high(ish) revs. When running there was a strong smell of fuel from the exhaust so it seemed to be running very rich so I presume it was a problem with the choke or ECU.
Its booked to go to the garage (under warranty thank god) on monday, but to top all this off it is now running completely fine, so I suppose they'll find nothing wrong with it. Does anyone have any ideas or ever experienced this themselves?
Richard Rowland

I had exactly this on my car last week. Mike was explained by the Highly ported head and cams not timed properly. The engine gets confused but the emmissions in the exhaust and over corrects when the car idles. It may well be a duff sensor. My short term fix was to disconnect the IACV connection on the engine side of the inlet manifold when the car was hot and running. Now the cams are timed corretly the car idles at 900rmp
tim woolcott

thanks tim.

Richard Rowland

My 98 29K miles 1.8i mgf played up this morning. When warmed up In traffic the idle speed would drop then rise when speed changes from 2000-3000 rpm to idle.
On one occasion stalling.Then correct itself.
never had problems before.Heater temp seems ok dial /heat no warning lights any help would be most gratefull
D Smyth

Sounds a little like the throttle sticking - can be due to crud build up, or, on plastic manifolds where a jubilee clip has been used to hold the air filter duct to the TB, distortion of the throttle body.

The throttle can be cleaned using a propreitary carb cleaning aerosol (once you remove the airfilter pipe). Or you can use this as an excuse to go and buy a new 52mm throttle body... ;o)
Rob Bell


My F was doing just the same - appearing to be running rich, then cutting out (not just from high revs, but at tickover at the lights too)

Changed the plugs, leads, rotor arm (the distributor cap was not in stock at the local MG dealer on Saturday) and since then, the car has purred at the golden 850-900 rpms.

I would definitely go for the plugs / leads.


I may have the original plugs i thought they were good for 40k miles Have to check the old service info thnks for your advice Dave
D Smyth

try looking at the air intake on the engine. My f used to doe this and then failed its mot with emmissions. found to be a rubber hose had been connected to the wrong breather pipe so was recycling the exhaust gases

Hasn't played up since so i shall leave the parcel shelf down for the time being
D Smyth

Change your old plastic TB for a new metal one 48mm or 52mm and your problem is solved...
My F is a 98 1.8i and it happened just the same thing, when warmed up In traffic the idle drop and rise from 2000-3000 rpm. The old plastic TB has gone.
bye Joao
Joao Barros Gomes

This thread was discussed between 25/04/2003 and 01/05/2003

MG MGF Technical index

This thread is from the archive. The Live MG MGF Technical BBS is active now.