Drawbacks of running rich?
 

As above, I wondered what the drawbacks are.

My car was running rich at last RR run and there is generally a smell of petrol a lot of the time. Has been like this since the downpipe was decatted.:(

Obviously you use more fuel, but are there any serious problems likely to occur and is a re-map the only way to solve this? :)

If its only do it since the DP was changed, have you tried changing the lambda sensor. Since its in the DP then it can be damaged when its removed and re-fitted.

I had similar symptoms to you when my lambda went, changed it and all was well again.

Where do I start?

Fouled spark plugs - missfires

Cabonisation of combustion chambers / valves / ports - soaks up fuel and also when hot ignites fuel - causing detonation

Oil dilution - need to change it more often

Fuel consumption - obviously

MOT emissions problems - excessive CO and incorrect AFR (like you'll pass without a cat anyway ;) )

Catalyst over-heating/melting/failure - blocked exhaust + MOT fail (decat so no worries there then ;) )


Obviously depends on "how" rich and when its running rich - if its off boost then as said above its likely to be a oxygen sensor problem.

However, if its whilst on boost - bear in mind they do run slightly rich anyway. I suggest looking elsewhere as the oxygen is usually ignored by the ECU - dodgy mapping/mods?

same problems here rossy i got 247bhp on the rollers a few weeks back and i should of been 290-310 i was running rich to. i changed my lamda but no success i still reaks of petrol have a look at wear the fuel pump regulator goes into the injector barrel cause my smell is coming from there so it could just be a simple seal thats gone.

If seriously over-rich, with many cars you can get "bore wash" as well - i.e. excess fuel cleans off/breaks down the nice lubricative (is that a word?) layer on the cylinder walls, causing much higher wear and/or potential for serious damage there.