2000 forerunner cel p0170

[Shepdog70]

I have a 2000 forerunner that does not run good when cold. It hesitates when I give it gas and backfires thru the airfilter. Sometimes it will die at stoplights. I changed fuel and air filter and tuned it up but no help. I took it to advance auto parts and had the cel checked. The code was p0170 ( left bank lean ). This could be several sensors. Any help will be much appreciated. Thanks

[kball]

You mean P0171 right? P0170 is Fuel Trim Malfunction. P0171 is fairly common. I would check for vacuum leaks and then clean your MAF sensor for starters.

[Shepdog70]

Thanks kball. I cleaned the MAF and checked for vacuum leaks. No change. Ichecked the pcv valve it was good. I cleared the code and it seems to run worse when the cel is off. When the light comes on it seems like the computer is trying to compensate for whatever issue it has and it runs better.

[kball]

Just making sure... when you clean the MAF you have to take it off the air intake tubing completely to get to the little passage ways where the wires are that need to be cleaned.

Here's a link that will help explain things better.

http://www.toyota-4runner.org/3rd-ge...elp-p0171.html


If you have cleaned the MAF properly and the code still pops up and there are no vacuum leaks (I'm assuming you disconnected the battery to clear codes after cleaning the MAF right?) it would seem to be the O2 sensor is next on the list. It will be the pre cat sensor and you can normally find good deals on them on Amazon.

Here's some sites to help you find the right sensor part number for your truck. Only use Denso!

http://www.urdusa.com/More-Products-...3k5tthki7atl17

http://www.densoaftermarket.com/oxygen-sensor.php