Toyota Repair Problems? Ask a Mechanic for Answers ASAP
Well, everything here points out to lack of fuel - misfire codes are caused by lean conditions and P0171 reinforces that argument.
Start by checking fuel pressure. If not 44-50 psi, fuel pump is not doing its job and needs to be replaced. If within specs, the we'll need to test the MAF. Let me know about fuel pressure first and then we'll continue if necessary.
Duly noted and will be taken into consideration for the overall diagnosis. In the mean time, what about that fuel pressure reading?
That's OK. Based on your replies I don't think I can work with you. I'll opt out so others may try. Don't reply until another expert responds or the system will revert your request back to me.
Are these the only code you've ever had in the system? Or have you had a VVTI malfunction code ever set This would be something in the 1300 series number P1346 and so on.? Have you checked for intake leaks? I wouldn't worry about fuel pressure at this point fuel pumps rarely fail on this vehicle and you wouldn't have just 2, 4, 6 misfiring you would have all six misfire codes.
An EGR valve won't cause this problem. Have you checked your intake leaks that would be common to the front bank of cylinders? I'm on my mobile device and have limited access for the next hour and a half. A plugged catalytic converter could theoretically cause this but would be extremely unlikely. Did you check the vacuum on the engine while it's idling? It should be at about 20 inches and if you do a snap throttle test it should drop down and instantly come right back up if it lags then it could potentially be restricted exhaust.
Do you have a picture of the three spark plugs from bank two? Do you have an active testing scan tool that will active test the VVTI controller for bank two? Is it currently running rough right now? If you clear the codes do just the cylinder misfire codes come back each time or is it intermittent that it runs rough?
Do you have the VIN available? Is the excessive carbon on all the plugs or just the front bank and when was the last time they were replaced? Do you have a picture of them?