Dear nairalanders, please help.

I have a 2010 accord that I believe is consuming too much fuel.
A full tank (18gallons) does 220miles without a/c (i.e 12 mpg approx.)

The car was taking very long to start. U have to crank it for about 10seconds before it starts. But this has been fixed.
The Mass air flow (air flow meter) sensor was replaced, and the fuel injectors were also replaced to fix the issue with starting.

Recently, the check engine light came up again. Hooking up a scanner, I have a PO420 code (catalyst efficiency below threshold bank 1).
But what is bothering me majorly is that the fuel trims are in the high negative (from -8 to -15), both short term and long term fuel trims.

Please what could be the issue.
Any help will be appreciated.

WebMania:
Dear nairalanders, please help.

I have a 2010 accord that I believe is consuming too much fuel.
A full tank (18gallons) does 220miles without a/c (i.e 12 mpg approx.)

The car was taking very long to start. U have to crank it for about 10seconds before it starts. But this has been fixed.
The Mass air flow (air flow meter) sensor was replaced, and the fuel injectors were also replaced to fix the issue with starting.

Recently, the check engine light came up again. Hooking up a scanner, I have a PO420 code (catalyst efficiency below threshold bank 1).
But what is bothering me majorly is that the fuel trims are in the high negative (from -8 to -15), both short term and long term fuel trims.

Please what could be the issue.
Any help will be appreciated.

Double digital negative value indicates you car is running rich i.e indication of high fuel consumption .Bocked catalyst issue can also contribute to high fuel consumption ,and since you already have a code pointing to Catalyst ,resolve the issue and confirm the fuel mileage again .
And if you need a competent professional to give you accurate resolution to all this issue.
call autologic @ 08061166316

Rev the engine up and see if the fuel trim readings falls back to - + 5....

chuks1137:
Rev the engine up and see if the fuel trim readings falls back to - + 5....

No i doesn't. It temporarily hits the +-5 range, but quickly goes back to double negative digits.
Presently getting it diagnosed. Would update with results. Thanks

WebMania:
Dear nairalanders, please help.

I have a 2010 accord that I believe is consuming too much fuel.
A full tank (18gallons) does 220miles without a/c (i.e 12 mpg approx.)

The car was taking very long to start. U have to crank it for about 10seconds before it starts. But this has been fixed.
The Mass air flow (air flow meter) sensor was replaced, and the fuel injectors were also replaced to fix the issue with starting.

Recently, the check engine light came up again. Hooking up a scanner, I have a PO420 code (catalyst efficiency below threshold bank 1).
But what is bothering me majorly is that the fuel trims are in the high negative (from -8 to -15), both short term and long term fuel trims.

Please what could be the issue.
Any help will be appreciated.

Replace offending cat. Simple.

kingreign:

Replace offending cat. Simple.

Lol. Not as simple as that bro.
Took the car to Autologic as advised by honmusa, and I must say I was quite impressed with the scientific approach to auto diagnostics. The problem was pinpointed with accuracy. Most people will just do trial and error, and throw parts at it.

It turned out that the catalytic converter had been removed. Also, the actron scanner I personally used to read the fuel trim data earlier was also inaccurate. This was discovered with an OEM scanner at Autologic.

So, to fix issue, Vtec switch was replaced along with a used catalytic converter from Ladipo (I must say those Ladipo dealers are something else. Make sure they test stuff and fix in ur presence before paying, if u can. Or better still buy new if u can afford it).

The car's performance has noticeably improved. But I will observe mpg gains when next the tank is filled.

Kudos to honmusa. He's a great man.

WebMania:

Lol. Not as simple as that bro.
Took the car to Autologic as advised by honmusa, and I must say I was quite impressed with the scientific approach to auto diagnostics. The problem was pinpointed with accuracy. Most people will just do trial and error, and throw parts at it.

It turned out that the catalytic converter had been removed. Also, the actron scanner I personally used to read the fuel trim data earlier was also inaccurate. This was discovered with an OEM scanner at Autologic.

So, to fix issue, Vtec switch was replaced along with a used catalytic converter from Ladipo (I must say those Ladipo dealers are something else. Make sure they test stuff and fix in ur presence before paying, if u can. Or better still buy new if u can afford it).

The car's performance has noticeably improved. But I will observe mpg gains when next the tank is filled.

Kudos to honmusa. He's a great man.

Mr, when you have a P0420 code which is what you posted, it clearly shows Cat below efficiency bank 1, what do you do? Run a Live scan, after which you delve into physical inspection of the cats which entails checking for Cat presence, absence or broken particles. Then replace with a good cat.

Did you replace cat or not?
Yes, what code were you trying to solve?
P0420.

V-tec codes are different from that of cat codes.

Take this arguement anywhere

kingreign:

Mr, when you have a P0420 code which is what you posted, it clearly shows Cat below efficiency bank 1, what do you do? Run a Live scan, after which you delve into physical inspection of the cats which entails checking for Cat presence, absence or broken particles. Then replace with a good cat.
Did you replace cat or not?
Yes, what code were you trying to solve?
P0420.
V-tec codes are different from that of cat codes.
Take this arguement anywhere

i appreciate your input bro. Ur intent was to help so I won't want to start a debate (though I would have loved to under a different circumstance)
The important thing is that the issue has been comprehensively fixed even along with other stuff, all thanks to honmusa and the autologic team.

Special thanks also to everyone that took time to reply.

kingreign:


Mr, when you have a P0420 code which is what you posted, it clearly shows Cat below efficiency bank 1, what do you do? Run a Live scan, after which you delve into physical inspection of the cats which entails checking for Cat presence, absence or broken particles. Then replace with a good cat.

Did you replace cat or not?
Yes, what code were you trying to solve?
P0420.

V-tec codes are different from that of cat codes.

Take this arguement anywhere

OP you owe this man one carton of star raddler