Running rich..not me the car!

[dave_p]

I have noticed just recently that when I start my car up from cold there is a petrol smell eminating from the exhaust pipes. Also today I noticed after a run of a about 30 mins that the ends of the exhaust pipes were lined with black soot. At the oment I am only using the car at weekends as I am working away. is it that the car is running rich or is it something else?

Dave

[chris547]

There are many reasons why it runs rich.

Have you had a computer check from the ECU. There are several sensors which adjust the fuel according to conditions, temperature, throttle, road speed etc. If any are faulty there will be error messages.

Is your rubber fuel line split and leaking a little?

How is the engine temperature?

Does your exhaust leak? If so fueling can be rich.

Chris

[Steve_T]

dave_p said:

I have noticed just recently that when I start my car up from cold there is a petrol smell eminating from the exhaust pipes. Also today I noticed after a run of a about 30 mins that the ends of the exhaust pipes were lined with black soot. At the oment I am only using the car at weekends as I am working away. is it that the car is running rich or is it something else? Dave

This all sounds quite normal to me. I think you might just be getting worked up over nothing, but am happy to be corrected on this, by those better informed than I.

Cheers
Steve.

[hut49]

Are you using Optimax? It grabs the mucous membranes up your nose a bit before the heat in the cats and exhaust fully vaporizes some of the more pungent organic fractions. Give it a good blast (once it's warmed up) and those sooty pipes will be all behind you!

[kim_400]

I think it says in the Bible that the car will run rich(er) until it's warmed-up. Given that it's the water temperature sensor that tells the ECU how hot the car's running, some people have attributed rich-running to a fault with the temperature sensor. I replaced my water temperature sensor but didn't see any change, apart from the gauge giving more sensible readings! - BTW, I replaced the sensor when I was experiencing problems with my coolant system, not rich running - I don't think you need rush out and buy a new temperature sensor just yet! -

As CHRIS547 said, there are a number of sensors that have a hand in fuelling, the oxygen sensor(s) being one of them. If the oxygen sensors read high levels of oxygen - duh! - in the exhaust gases, the ECU should compensate by enriching the mixture, thus improving combustion. The oxygen sensors can give dodgy readings if (a) they're bust or (b) additional oxygen is getting into the exhaust system somehow. I mention this last point only because I had my exhaust manifolds re-faced and gaskets replaced recently. According to my friendly indie, the manifolds will actually suck (some) air into the exhaust if the gaskets are blowing. Paradoxical, hmm?! Anyway, since having the manifolds done, my Chim has been much better behaved at lower speeds. If my man is right about the sucking, I may be experiencing less erratic fuelling.

These are just some ideas. Don't worry about your sensors / manifolds being duff just yet. When I had my car serviced a couple of thousand miles ago, there were no sensor faults and my car always runs rich at startup. My previous car, an MX-5, did too. I think it's quite normal.

If you are at all worried, have a chat with your local garage. If there's any cause for concern, get them to plug their computer into your baby. If there's anything wrong with your sensors or pooter, this should be able to tell you. I doubt they'll charge you much for it - Mazda charged me around £20 with the 5.

Hope this helps.

happy motoring...

>> Edited by kim_400 on Saturday 4th September 09:57