CL9 Poor fuel economy

[falco]

My Euro has 153000ks on it and has started to get really bad fuel economy.
I have always worked out my fuel economy since purchasing the car new, and recently it has gone from 8l per 100k up to 12l per 100k. This is with exactly the same driving conditions.
I noticed my exhaust pipes seem rather black sooty colour. I have recently changed my spark plugs (they were done at 100,000k's) and the old plugs were sooty/black around the diameter and white/clean in the middle.
Is there anything in the engine that would go faulty to cause this. Is it worthwhile taking to the dealer. ???
I have checked all the obvious like leaking fuel tank, and tyre pressures.

[dtngo]

Sound like it's running rich. Get it to a Honda service to check for fault codes.

[shmivic]

Timing?

auto or manual?

std ecu?

id suggest the timing is out. Does it ping under load?

[falco]

Auto, Standard ECU, and havent noticed any pinging.

[HunterZero]

Bad fuel?

- HZ

[aaronng]

Doubt you'll see fault codes on this, but the primary O2 sensor can read a false lean condition, causing the injectors to put in more fuel to protect the engine. So change that or test that with a known working unit first.

[duzy]

no point asking if auto or manual
no point asking if it has std ecu

he has had the car since new, going for 8L to 12L per 100km.

try cleaning ur injectors, change ur fuel pump. otherwise yeah, my car was going 12L per 100km aswell, now its gone back down to 10.5

[shmivic]

no point asking if auto or manual
no point asking if it has std ecu

he has had the car since new, going for 8L to 12L per 100km.

try cleaning ur injectors, change ur fuel pump. otherwise yeah, my car was going 12L per 100km aswell, now its gone back down to 10.5

asking because auto and manual gearboxes produce different internal loads.
increased load = decreased fuel economy.

agree could be injectors, but there a stab in the dark on a newish car and doubt they would be failing already. Your car isnt misfiring is it?

prefferable to try basic tune methods before getting drastic and changing everything straight away.

whats the weather like in your city at the moment?

[tat01]

8L per 100km? wow im barely pulling 9.5L/100km and i just drive on the freeway to the city and back mostly :/

[tron07]

i get avg of 10-11L per 100km syd city roads

[shmivic]

ive had average down to 6.5L/100 as i drive mostly fwy to and from work
city is around 8.5L/100 (9-10L/100 with a/c on)

[EuroAccord13]

Also, try changing the air filter and fuel filter.. At 1530000ms.. the car should be on it's third fuel filter now.