Renault Clio III - Idling Issues

[swa110w]

Renault
Clio III - Dynamique
1.4 Petrol
2006
35,000 miles

Got a bit of a puzzle about my Clio. It's been playing up when starting from cold: erratic idling and occasionally dropping to no revs and cutting out. Despite this, it still starts first time most of the time (although it took a few goes after a three-day break at Christmas). It seems to get better once I've driven it for a while, although the engine still sounds really rough to me - almost like a diesel. There's also a high-pitched squeal when I start the engine, continuing for a few minutes into my journey - don't know if this is related but I thought I'd mention it.

Anyway, I've had it into the garage and they ran the diagnostics on it. This didn't reveal any error codes but the Engine Coolant Temperature was unresponsive and fixed at what looked like -40 (I was reading it over his shoulder and haven't really got a clue). It didn't move despite heavy revving. Strangely, the dashboard temperature gauge seems to work okay.

So, presuming it was a faulty ECT sensor, they had the car in again today, and replaced the sensor. However, apparently this has not fixed the problem and the reading is still the same. They're keeping it in tomorrow and are going to check the wiring. They also said there might be two sensors? (though I'd have thought they'd have checked that first).

Anyone got any suggestions as to what this might be?

 

[Burnerman]

Personally I'd be checking for air leaks around the inlet manifold / fuel injection area, especially at the ends of the numerous rubber pipes around there.
Then I'd turn my attention to the idle control valve (ICV) performance as well as replacing that coolant temp sensor.
This particular sensor is not the one that sends information to the dashboard gauge - it communicates with the ECU.
The squealing you mention is likely to be caused by a slack alternator / PAS belt.
John

 

[swa110w]

An update:

They've replaced the ECT sensor, and that hasn't fixed it, and they've checked the wiring and can't find a problem there. They are having it another night, so they can do some research to try and get to the bottom of it.

The odd thing is, despite the ECT reading a constant "-40", and it showing symptoms of this sort of problem (erratic idling, cutting out, rough sounding engine etc.), the engine hasn't reported any error codes, apparently. Also, the light for this kind of problem hasn't lit up on the dashboard.

They've suggested another scenario could be a problem with the engine computer not actually reading the temperature, which could be costly to fix (although they said that was a worse-case scenario).

So does that change your predictions at all?

 

[Burnerman]

I'm a bit confused about your comparison with a diesel engine...the engine should be perfectly smooth at all times.
How does the engine start once it is warm? Does it idle well, accellerate well and give acceptable fuel consumption?
If the trouble is only when the engine is cold, it would indicate incorrect fuelling due to the temperature sensor (only use a genuine item, by the way) but if the engine is always grumpy I'd be thinking about the throttle body itself....the newer clio's are getting issues with these.
John

 

[swa110w]

The engine definitely sounds rough, sometimes really chugging along. This is both when it starts and when it is warm. The garage reckons this could be due to over-fuelling from the ECT problem.

It doesn't idle very well, particularly when I start it from cold. It fluctuates all over the place and sometimes gets so low that it cuts out. This does seem to sort itself out after I've been driving it for a while and, on the whole, it accelerates okay. Sometimes it takes a second to catch up with my pedal though.

Fuel consumption I'm not too sure about because I don't use the car often enough (I walk to work and generally only travel short distances). I haven't noticed anything unusual though.

 

[Burnerman]

If the engine is overfuelling, then the time honoured spark plug colour test still comes up trumps - the plugs will be sooty if this is the case.
Presumably the car has been serviced at some time, so the plugs, air and fuel filters aren't the original ones
Have a look at the BBA-Reman website under throttle bodies, and see if there are any clues for you there.
John

 

[Belle427]

if the live data shows engine coolant at minus 40 then its got to be related to the problem in my eyes. Do you know if they checked the wiring back to the ecu?

 

[swa110w]

I don't actually. He said he had some wiring diagrams up on the computer when I rang him, so maybe he was still investigating that. I get the impression he thinks it is ECT-related, but is puzzled about where the problem lies.

 

[libby lou lou]

Might be miles out, how old is the cat?

 

[swa110w]

The cat? Or the car?

The car is March 2006, so almost 6 years old.

The catalytic converter? Not a clue. Could it be as old as the car?

 

[swa110w]

Another update:

The garage now thinks it might be their diagnostics software that is at fault. They said there's official Renault diagostics software for reading the ECU as well as a generic version. They've got the generic version and this is why they think it might not be picking up the ECT readings.

So instead they decided that it might be the throttle body and so they've cleaned that out and it seems to have done the trick. I've got the car back now and it certainly seems to drive better. It now idles steadily and it feels more responsive somehow (although that's probably psychological!). I'm still to try it from a cold start so we'll see how it goes tomorrow morning.

However, there's now another problem! The idle now seems to be sticking high. It's whenever I stop the car and take it out of gear, the revs remain high, like I've got my foot slightly on the pedal (about 2000rpm). When I do actually tap the accelerator, the revs return to normal (about (1000rpm). It seems like it's getting caught or something.

Any suggestions? Looks like I'm going to have to take it back to the garage...

 

[swa110w]

Further update:

I took it to the garage but they couldn't find anything wrong it. I don't think they could reproduce the problem. Apparently everything is looking okay - nothing obviously out of order...

So I don't know what to do now. I'll just have to keep an eye on it, I suppose.

 

[rsymes2k]

Sounds like the butterfly in the throttle body is now sticking from where they've cleaned it?

I had this problem on my old rover and just replaced it with a spare one for £15 from the scrapheap.

Or it may just need lubrication in the throttle body as it's probably plastic it won't be a perfect fit