[Piyke]

So my O2S1_WR_Lambda Ratio readings spike to negative readings and MPG is about 18mpg highway.

I have replaced spark plugs, AF and O2 sensors (all OEM) and theres no relief.

STFT is less than 5% eitherway while LTFT is between -4.7 to -5.5%. Odometer reads 216k miles and there are no codes whatsoever in the ECM.

See pictures attached any help will be appreciated. Have searched the internet and I'm at my whits-end

 

[2i2dk1ny2i3]

18MPG on the highway in a 2.4L!

i think you're currently getting a little worse MPG than a Hummer


did you start with obvious things like a leak under your car from the Gas Tank?

 

[Piyke]

18MPG on the highway in a 2.4L!

i think you're currently getting a little worse MPG than a Hummer


did you start with obvious things like a leak under your car from the Gas Tank?

No leaks and no smell of gasoline whatsoever. I think its rather 18mpg combined cos I do sit about 30mins in traffic before hitting the freeway when going to work and same when returning. So in all about 60mins of crawling traffic.

However the fluctuations in lambda happen also on freeway driving

 

[jfuredy]

Does your engine consume oil? I had fuel economy/power problems on my '01 I4 Accord and it turned out to be a clogged catalytic converter from oil consumption. If the engine can't breathe well (either in or out), it will decrease your fuel economy without necessarily setting a code because it will adjust the fuel demand to match the air it's getting. Just a couple of things to think about. Good luck with it.

 

[greg1c]

With a long term fuel trim of about -5% is not that bad. But the ECM is removing fuel so something is up.

The normal cause would be a leaking injector or something blocking air into the engine like a clogged air filter or collapsed air tube. Also, you could have a lot of blow by gases as well. Also, higher than normal back pressure in the exhaust could cause similar issues.

Bottom line is anything under +/- 10 is generally considered good fuel trims.

 

[Piyke]

Does your engine consume oil? I had fuel economy/power problems on my '01 I4 Accord and it turned out to be a clogged catalytic converter from oil consumption. If the engine can't breathe well (either in or out), it will decrease your fuel economy without necessarily setting a code because it will adjust the fuel demand to match the air it's getting. Just a couple of things to think about. Good luck with it.

Thanks mate! Difficult to say if it consumes oil cos I have a slight leak from the vtec solenoid assembly area. However the left over from oil change about 0.8 quartz is enough for my 3k miles change interval so I dont think it consumes oil. It doesn't smoke as well. But I do get a sulphur smell when I start the car in the mornings.

Can a clogged Cat not throw a p0420? Cos I have no codes?

With a long term fuel trim of about -5% is not that bad. But the ECM is removing fuel so something is up.

The normal cause would be a leaking injector or something blocking air into the engine like a clogged air filter or collapsed air tube. Also, you could have a lot of blow by gases as well. Also, higher than normal back pressure in the exhaust could cause similar issues.

Bottom line is anything under +/- 10 is generally considered good fuel trims.

I think a leaking injector may be a likely cause. Sometime years ago a roadside mechanic inspected my injectors (car was in limp mode from clogged vtec filter I later learnt) and I don't recall him changing the o-rings. I guess I'll start by replacing all injector o-rings.
In the medium term, I'll finally have to get a compression gauge to check the cylinders. Thanks a lot.

 

[Drew03Accord]

But I do get a sulphur smell when I start the car in the mornings.

Sulphur smell = clogged cat

 

[greg1c]

So when I said leaking injectors, I meant extra fuel leaking into the combustion chamber not air passed the Orings