2009 Clio 1.2 petrol, intermittent low power when cold.

[Mervyn44]

I recently bought this car in Glasgow and drove it around 100 miles home to Belfast, seemingly without issue. Once very briefly I noticed a drop in power but this only lasted a couple of seconds and didn't come back so I thought little of it. I arranged an MOT and when I started the car that morning it behaved exactly as you would expect when running out of petrol - chugging, no throttle response or power. Thankfully it recovered after about 30 seconds of struggling along my street and I headed straight for the petrol station. It was fine after that and although it failed the test this was only because of a faulty seatbelt and some minor brake work.

Now I've noticed that when started cold there is often a rough idle at around 400-500rpm which if left to itself will eventually splutter and die. Trying to use the accellerator has no affect at all. Its not as if the car struggles to respond to the accellerator, its more as if the accellerator is completely disconnected, no response at all! The problem seems to resolve itself after a min or two, revs jump up to normal and car behaves perfectly. Other times switching off and on again fixes the problem.

It appears to be a cold start issue, apart from that brief moment of power loss when originally driving home I have not experienced any probs when the car is up to temp. The car has also worked fine previously from startup and I'm wondering if it is more regular now because the weather is getting cooler?

I have a Lexia/Diagbox interface but obviously this won't suit a Renault, what is the equivalent for these cars?

I'm hearing suggestions such as oxygen/lambda sensor (are they not the same thing?)
Blocked CAT
Throttle body

Obviously more light will be shed when I get a computer connected but any and all comments are warmly welcomed.

Just to repeat, I've done about 200 miles in the car up to now and have not noticed any issues on 199.5 of those. That last half mile has the few times when the problem has existed following startup when cold.

Many thanks - Mervyn.

[Mervyn44]

I'm still waiting for my generic OBD2 code reader to arrive.

Tested the coolant temp sensor wiring for voltage and continuity - all ok.

Tested temp sensor, was reading around 4500 kilo ohms when cold and dropped to 250 when dipped in water that had just been boiled - so this seems about right too, although I heard it said in other places it should be around 1500-2000 when cold. either way it seems to be responding so I guess I might check out the lambda sensor next.

- Merv.

[Mervyn44]

Just tested resistance of O2 heater circuit, came out at 3.6 ohms although I have no idea what it should be, some places say 5-10 ohms, another source suggested 3.6 was high. I cannot locate anything relating to these specific O2 sensors.

[Mervyn44]

Got my OBD2 reader today, engine coolant and O2 sensors appear to be functioning perfectly, values are normal. No codes are stored or appearing,no lights are lit.

The only weird thing is no signal from the MAF, just a consfant zero! No idea if this is a problem or just my cheap OBD2 reader. Intake air temp sensor was also reading almost 40c which seems a bit hot to me, maybe not, I'll have to check this out.

[Mervyn44]

Well I now realise why I have no MAF readings, this car doesn't have one! It relies on the MAP sensor on the throttle body... which appears to be working fine according to the data. Think I might be flogging a dead horse with this thread!

[veralum]

Did you ever resolve this?