stalling when cold, runs extremely rough until it warms up

My 2005 Petrol 1.4L C3 has recently started to stall when first started. It isn't associated with extreme temperature (starting at 23C).

The car runs extremely rough until it warms up, after about 4 minutes. Giving it throttle just stalls it, it often takes several starts to keep the engine running. The problem does not happen every time the car starts when cold.

I have one ECU error 'Catalyst System Efficiency Below Threshold', but this existed prior to the problem. The thermostat has also been recently replaced and I believe it is functioning correctly. Once the car warms up, it runs quite smoothly, however sometimes appears to 'drop out' when accelerating, which may be an injector issue and unrelated?

Any help would be appreciated!

Richard

Hi, my 2003 1.4 sounds similar. It is particularly bad in winter but not too bad this weather. A burst of throttle will cure mine otherwise it takes about half a minute to stabilise. No further trouble for that day.
I entrusted it to the local garage who relieved me of nearly £400!!!, but the fault is still there, after replacing two injectors.
It runs so well otherwise.

Hey Patt

I know the feeling. Got a couple of those in stock, knowing my C3!
Hopefully someone can shed some light on the issue.

Hi Richard,

I have one ECU error 'Catalyst System Efficiency Below Threshold',

I would connect up the OBD2 reader again, and get all the codes, if there are any more, and note the description (which may be incorrect) and the 'P' code too.

If you can clear any of the codes, do that and try the starting/running/stalling game again and gather up any remaining codes and post them here.

If you don't have an OBD2 reader, they are cheap enough, try C3 compatible OBD2 reader from Amazon which is going to give you loads more information to help track down the problem.

I don't recommend changing C3 parts on a whim, its a complicated computer controlled system and takes a fair bit of diagnosing before you can be confident on changing the correct part The lexia tool (info here) tool is the most comprehensive system for doing the diagnosis.

I would connect up the OBD2 reader again, and get all the codes, if there are any more, and note the description (which may be incorrect) and the 'P' code too.

Thank you. I will do so tomorrow and post the results. Thanks for the Lexia link, I'll have a look.

I have tried to clear both these faults without success via the reader and have left the battery disconnected for 30 minutes.
I am using a Bluetooth ODB reader. The code 'P0463' has been logged for a few months, prior to the idling fault developing, but some help with that one would be great too!

Often, the car runs perfectly well from a cold start, I'd say on average it would behave abnormally 1-2 times a week.

Any help would be appreciated

Your P0463 could well be a wiring/plug/socket problem to do with the fuel level sensor. There could be a connection in that the same plug/socket that carries the fuel level information as some other signal that affect the engine running. What would the odds be in that P0420 is caused by a wiring/plug/socket problem - and its on the same bit of wiring.

I have not looked at the wiring for your car and may be completely off, but I wouldn't be the slightest bit surprised if both of those signals plus some others that affect the running all appear on the same plug somewhere.

I have tried to clear both these faults without success via the reader and have left the battery disconnected for 30 minutes.

With a wiring problem, the code won't clear as the fault doesn't clear with a reset/power down.


This C3 Haynes Manual has diagrams of the wiring and the plug/sockets that carry the wires.

Thanks for that. I'll take a look. Had a bit more of a look online and someone suggested it could be a faulty MAF sensor causing the issue. I'm now starting to have issues that sound very similar during normal driving. Do you know the MAF sensor is located on the C3 petrol? Is it by chance incorporated into the throttle body? I have purchased Lexia, so maybe that will be able shed some more light on things.

Do you know the MAF sensor is located on the C3 petrol?

No MAF on the petrol, that's a diesel thing, to test the diesel MAF, disconnect it and see if the car get better.

The closest thing to a MAF (Mass Airflow Sensor), could be the IAT (Intake Air Temperature) sensor - this appears on the petrol engined C3 and is part of the throttle body.

Lexia is the tool to read IAT values, live readings and static readings can all help.

There is also a MAP (Manifold Pressure Sensor) located on the inlet manifold, you can lexia this too.

Ok that clears things up. I'll wait for Lexia and see how I go!