Running rich?

Im trying to track down a problem with my 2011 C3 1.4 VT which has covered 47000 miles.

1: There is no engine warning light displaying

2: The car pops / backfires on the over run

3: Fuel consumption has dropped from about 40 mpg to 33 / 34 mpg.

I guess the car is running too rich and have wondered if this may be due to a faulty lambda sensor but in the absence of any anti pollution warnings maybe this is unlikely.

Any pointers to help locating this fault?

Alec wrote:Im trying to track down a problem with my 2011 C3 1.4 VT which has covered 47000 miles.

1: There is no engine warning light displaying

2: The car pops / backfires on the over run

3: Fuel consumption has dropped from about 40 mpg to 33 / 34 mpg.

I guess the car is running too rich and have wondered if this may be due to a faulty lambda sensor but in the absence of any anti pollution warnings maybe this is unlikely.

Any pointers to help locating this fault?

Hi Alec


Option 1
Connect up an OBD reader, just like this one here or this one on Amazon.co.uk and read the codes. You may also get some live data for the fuel trim, but then again, you may not.


Option 2
If you have a spare older laptop, the fully capable way to go is with this lexia tool which can read codes and monitor all the live data to help diagnose the fault. But, read up about it first here.

Thanks for the reply.
The information seems to suggest Windows XP is required. Have I understood that correctly ?
If so I guess I would drive to the small independent up the road and ask for a diagnostic to be run. I dont run Windows at all on my laptop ... Linux user.
I was hoping to have a few clues up front prior to fetching up at the garage.
Thanks again

Alec wrote:The information seems to suggest Windows XP is required. Have I understood that correctly ?
If so I guess I would drive to the small independent up the road and ask for a diagnostic to be run. I dont run Windows at all on my laptop ... Linux user.

There is not Linux/GNU or wine for Lexia/Diagbox, so you could go for the cheap option that I suggested and get an an OBD reader - a stand alone unit that is generic but doesn't need a laptop.

Alec wrote:If so I guess I would drive to the small independent up the road and ask for a diagnostic to be run.

You can do the basic OBD stuff yourself (use this). The advantage of having your own reader is that you can read as many times as you like for a single cost that is less than a single read from a garage but it may not cover all the possible faults.

Alec wrote:I was hoping to have a few clues up front prior to fetching up at the garage.

Yes, good idea. See above

I have edited my reply to make it clear that I offered 2 options. This wasn't clear

Sounds good. I had (wrongly) assumed a laptop was required for both options.
I will order one first thing.
Thanks again for your reply and suggestion.
Appreciated

Alec wrote:Sounds good. I had (wrongly) assumed a laptop was required for both options.

It was my fault. Its easy to forget that others are not so aware of these devices and how to get them to work.

Alec wrote:Thanks again for your reply and suggestion.
Appreciated

Not a problem.

Please post any codes you find here

Read the codes
Clear any that will clear
Run the car again
Re-read the codes

Hi, when my C3 (Bivalent, then) told me a mysterious fault (antipollution fault) I bought a cheap OBDII diagnostic tester and I was very glad to have it: a. You can see, that there are some things that are, gladly, NOT faulty. b. It gives you an idea about the faults, if you are lucky this is already enough (showed in my cars case indeed that there was something faulty with injector 1 - by splattering wiperwater) and 3. it made it possible to set back the stored faults then, so to have a clearer look on the actual fault.
And 4. -and first- I did not feel so helpless any more , as I do not always have the leisure to bring the car to be diagnosed or repaired ... - and I like it very much to know what is the matter with my poor car ...
So I find those simple testers are a big help - just when you are not a big mechanic yourself.

This problem turned out to be caused by a faulty thermostat of all things. ECU was seeing a cold engine and applying fuel mixture to suit when, in fact, it was running at normal temp.

That problem solved I am left to wonder how one is supposed to remove the fusebox cover in the glove box for this model of car.
There doesnt seem to be any clips or fasteners ..or perhaps I am missing something obvious?

Thanks
Alec