Dear Professionals, I need help.
I drive a 2003 Toyota 4runner 4.7l, V8. The fuel consumption has increased.

I used a basic OBD scanner and got the following codes:
P0330 - knock sensor 2 circuit Bank 2;
P0420 - Catalyst System Efficiency Below Threshold (Bank 1) and
P0308 (Pending) Cylinder 8 Misfire.

Freeze Frame: P0330
Fuel Sys1 CL
Fuel Sys2 CL
Calc Load 18.43%
Coolant Temp 75.0C
STFT B1 -20.32%
LTFT B1 -17.97%
STFT B2 -20.32%
LTFT B2 -17.97%
Eng Speed 2150.90Rpm
Vehicle Speed 0Km/H
I.A.T 38.0C

The car moves ok and does not seem to misfire (at least not noticeable to me).
Kindly assist me with the interpretation of the above, what could be the possible cause(s) of the increased fuel consumption and suggested solution.
Your input will be highly apreciated.

Some questions for you here:
1. Has this vehicle ever overheated so badly before?
If yes, what has being done previously on it due to that incidence?

So here's what I think is happening here:
1. Each time you erased the codes with your code reader, vehicle performs perfectly. The check engine light, along side the codes, only pops up, when it has being driven for along time, and when the engine has gotten to its operating temperature.

2. You appeared not to observed any driveability problems now, because, that vehicle is a V8, and a pending or current misfire problem, does not show up, in such away you'd feel it on a 4cylinder engine. This is because the number of cylinders( on that vehicle, tends to canceled out any potential misfires. Please do note, only if its a SINGLE CYLINDER MISFIRING, AND IN A PENDING STATUS. You'd only noticed a misfiring cylinder, if its severe(current), on idle, on 4/6 cylinder engines. But on V8+above, its a different ball game entirely.

3. Reviewing your freeze frame data, you got to fix the P0330 code FIRST, along side the P0420 code.

The knock sensor wire may have chamfered, if that engine has undergone a serious overheating before, or rodent could have chewed it, causing an open circuit problem.

4. The P0420 code, which is current, talks about the catalytic converter, not properly doing its job of reducing vehicle emissions(harmful gaseous substances).

It may not be the catalytic converter that is pretty bad, as you maybe think.

An exhaust leak around the neck of the catalytic converters, or anywhere on the exhaust system, would trigger this code, and hence the excess fuel consumption you're experiencing.

From the fuel trims in the freeze frames, the problem is occurring more on bank 2, which is the cylinder head by the driver side.

In solving the P0420 code, you need to focused more on banks 1&2, sensors 2, on both banks. Those are the sensors responsible for telling the ECU, if the efficiencies of both catalytic converters (post ones I mean), are working at the set % efficiencies.


PS: The pending misfire on cylinder #8, would in due time come(becomes Current).


I hope this would helped you in sorting this issue.



Regards,
Joseph

Thank you Sir.

I have not experienced any overheating before.

I will share your opinion with my Mech to see whether we can achieve a fix.
Thank you.

TRYGO:
Some questions for you here:
1. Has this vehicle ever overheated so badly before?
If yes, what has being done previously on it due to that incidence?

So here's what I think is happening here:
1. Each time you erased the codes with your code reader, vehicle performs perfectly. The check engine light, along side the codes, only pops up, when it has being driven for along time, and when the engine has gotten to its operating temperature.

2. You appeared not to observed any driveability problems now, because, that vehicle is a V8, and a pending or current misfire problem, does not show up, in such away you'd feel it on a 4cylinder engine. This is because the number of cylinders( on that vehicle, tends to canceled out any potential misfires. Please do note, only if its a SINGLE CYLINDER MISFIRING, AND IN A PENDING STATUS. You'd only noticed a misfiring cylinder, if its severe(current), on idle, on 4/6 cylinder engines. But on V8+above, its a different ball game entirely.

3. Reviewing your freeze frame data, you got to fix the P0330 code FIRST, along side the P0420 code.

The knock sensor wire may have chamfered, if that engine has undergone a serious overheating before, or rodent could have chewed it, causing an open circuit problem.

4. The P0420 code, which is current, talks about the catalytic converter, not properly doing its job of reducing vehicle emissions(harmful gaseous substances).

It may not be the catalytic converter that is pretty bad, as you maybe think.

An exhaust leak around the neck of the catalytic converters, or anywhere on the exhaust system, would trigger this code, and hence the excess fuel consumption you're experiencing.

From the fuel trims in the freeze frames, the problem is occurring more on bank 2, which is the cylinder head by the driver side.

In solving the P0420 code, you need to focused more on banks 1&2, sensors 2, on both banks. Those are the sensors responsible for telling the ECU, if the efficiencies of both catalytic converters (post ones I mean), are working at the set % efficiencies.


PS: The pending misfire on cylinder #8, would in due time come(becomes Current).


I hope this would helped you in sorting this issue.



Regards,
Joseph

I can see that bank 1 and bank 2 fuel trim values are exact. What scantool did you use?

EngRichie:
I can see that bank 1 and bank 2 fuel trim values are exact. What scantool did you use?

Please see the attached.