Every little helps....

[Landyman]

When l took off my inlet manifold to replace the HT leads, l noticed that there are two sensors and a hose connected to the manifold.

All three were not really that tight, and would possibly allow some air to get past.

So l replaced the O-rings on the two sensors. The hose at the rear was just a push fit. I fitted an O-ring on the stub pipe so now it seals better.

These things make a difference, as it’s downstream from the MAF.

I’m sure it’s a bit smoother in the warm-up phase now.
There was a tendency for it to hold on to revs a bit but it’s not done it since.

I had a secondary air leak on the inlet manifold in my Ferrari (small bore air hose detached under the manifold, no idea what it was for!) and it did cause it to run a bit rough for the first mile or so.

It was very hard to see, let alone get the pipe back on. Somebody had tweaked the idle mixture on that bank of cylinders to try and fix it, the setting was a mile off when l fixed the actual fault, fortunately easy to adjust.

 

[Djw John]

This on the Clio? Cos we don't have MAFs! They run a MAP sensor instead. Which is one of the ones you'll have removed

 

[Landyman]

Well, there’s something l learnt today! I guess that it’s the throttle body l was looking at, and thinking it’s a MAF.

Anyway, l’d advise checking these small items as they all make a difference and the O-rings only cost a few pounds for a box of hundreds in various sizes which will be useful for years.

 

[MonkeyKnifeFight]

If you check these sensors whilst the car is running you'll notice they seem much more secure due to the vacuum.

 

[Landyman]

Yes they will but if they allow secondary air flow due to poor sealing, it will disrupt the running of the engine.
Only slightly, but for the sake of 50p worth of O-rings it’s surely worth putting right.

 

[DomP182]

I thought this might be the reason for my dropping and eventually stalling idle that I've still not solved, am I right in saying an air leak is more likely to raise the idle

 

[Landyman]

Easiest thing is to discount the possibility by replacing the O-rings in the sensors. It can’t do any harm, and if it doesn’t cure the fault at least you’ll know what it isn’t.