I'm getting ready to sell my 4Runner so I figured I'd do some basic maintenance for the next owner. I replaced the plugs, wires, boots, oil and air filters, and the PCV valve. I then disassembled the MAF and cleaned it and the throttle body with brake cleaner. About 50 miles later the check engine light comes on, so I take it to Autozone and it's throw the common 'bank 1 too lean' code (P0171), yet it still runs the same (very well). Reading on the net, I found a couple of the common culprits are O2 sensors, the MAF, and vacuum leaks. Because it happened so soon after I did the work, I'm almost convinced I may have inadvertently damaged the MAF somehow. I know for a fact I didn't break the little wires and I know I took it apart and put it back together correctly. I'm going to go over it once more but if that doesn't work I'd like to find a known good working MAF, hopefully fixing the CEL and allowing me to sell my 4Runner knowing it needs nothing.

Did MAF's change from '96 to '02? Do I need to get a specific one for my 2000 (the '98-'00 MAF)?

 

Using brake cleaner on the MAF might not have been the best choice.

 

Yes the 2000 takes a different MAF than a 96-97, but the later model is less expensive. Before you change it out you can test the resistance, the procedure is in the service manual.

Good luck. I've been chasing a P0171 since January...

 

How did you take apart the MAF? In no way should you have been able to do this and more than likely damaged it if you did so. 96-98 MAF's are the same and 99-02 MAF's are the same. I changed my 97 MAF over to the 99-02 style for better airlow and much smaller part cost if I ever have to replace my MAF. $500 vs $130

 

Thanks for the info guys.

hotlavaaaa I was thinking the same thing, though I read to do so many many times here and other places on the net.

By taking it apart, I unscrewed the actual sensor from the housing with the two screws which held it in place.

 

I would suggest taking it out again and cleaning the bulb front and back with CRC electronics cleaner. Be sure to let it dry well before reinstalling it. Then pull the 15amp EFI fuse and replace. I really couldn't see you messing the MAF so bad you need a new one.

Good luck.