Low rpm at idle

Just recently I’ve been experiencing low rpms at idle (gets worse when warm) I used to see a nice steady 800 rpm at idle but now it runs between around 650-700 and dips as low as 500.

Oil pressure is fine, no loss of coolant, runs fine when exercising the loud pedal, new plugs around 1000 miles ago.

Any ideas of where to start without replacing the obvios plugs / leads / tps / coilpack / etc all at once ?

You just need to give your base idle screw a bit of a tighten. They do rattle loose a little over time. Its a 3mm (i think) alan key bolt in the middle of the throttle bodies right up against your airbox back plate.

Get the car nicely warmed up then while it is running slowly turn the screw inwards. I bet you will only need half a turn.


old post I know, but after some help!

My 340R K series 190 upgrade looses idle when coming up to juctions a speed and having to come to a stop! As soon as you dip the clutch to coem to a dead stop it looses idle and cuts out!

I have looked for this screew but can’t find it, I will post a picture up of my engine then please could some one show me where it is?

thank you


No problem Nathan, it can be quite hidden depening on how your fuel injector wiring and throttle cable and fuel pipes are routed. I will have a look for a picture also.

great I will get the picture up when I get home from work, thanks sean! I be it is obvious!

hear is the pic, sorry it is not great, but only have access to my phone at the minute!



Can’t see the idle screw from those pictures, but basically the idle screw is part of the linkage where the throttle cable joins the throttle bodies.

found it tonight sean and it worked, thankes for your help mate!

Turning the idle control screw may be masking another problem… check the vacuum hoses which run along side the head, on the pics posted above you can see a lot of discoloration due to heat. Chances are one of the T-pieces has cracked.

I used some windscreen washer T-pieces from my local parts place to fix - changed the lot along with all the vacuum hoses and its make to rude health again

I thought they were supposed to idle at 1200rpm…

I thought they were supposed to idle at 1200rpm…

That’s correct.


Plumbing in your pictures suggests that you don’t have an IACV fitted - is this correct? If so, this may explain poor idling.

Just seen your post now, what is a IACV? The car is a 190bhp upgrade Lotus factory car, by the way.

Thanks for help