2kMax running lean - please help

[jmartinson]

My car's been running lean for a while according to the error code on the computer, I have occassional knocking, and a considerable loss of power throughout the RPM range. It's got about 100k miles on it. I've got a Budget Exhaust Y-pipe and a K&N air filter. I only use 93 octane gas from Chevron or Shell, and I often use either an octane booster or Lucas fuel injector cleaner/additive to try to stop the knocking.

I replaced all my coil packs about 6 months ago because the engine was intermittently chugging hard & that fixed that problem.

Every month or so it will seem to have it's original power for a few seconds, but if I rev it up to 4k rpm or so it will lose power again for an indefinite period of time like it's adjusting the timing in response to the engine knocking or something like that.

The MAFS is only getting 5V from the computer, but Haynes says it should be 12V. I don't really trust Haynes' electrical specs (been wrong before) but I don't know where else to go to check that.

I tried some Lucas fuel injector cleaner, and that made a noticable improvement for a while, but subsequent treatments just plateaued.

Also (key to the problem I'm sure) I made the mistake of letting an alcoholic chick borrow my car shortly before all the problems started and I think she drove over some parking lot curbs or something.

I've got a set of O2 sensors on order, but if that doesn't fix it I'm not sure what to do next.... get the injectors cleaned & flow tested, replace the MAFS, check pressure in the fuel rails???

I've had a tech at Autozone check the codes for me a few times and it never says anything other than "Engine running lean".

Any helpful ideas would be greatly appreciated!

Thanks!

-Jacob

[getgopi]

I had noticeable loss of power and mileage starting in January on my 1996 Maxima with 96K miles. The exhaust pipes, muffler, oxygen sensor and catalytic converter were rusted out. I replaced them end of February and she runs fine now. It is probably the O2 sensors and/or a combination of what I have mentioned above. Have you done a visual inspection of your exhaust pipes?