'98 4Runner 3.4. I've swapped this into my '91 and its been getting 14mpg on the highway, 11 in town. A couple of days ago I ran it through a high pressure touch-less car wash and now it runs like a turd. It stumbles, pops out the exhaust and just wont pull. If I can get it up past 4000rpm it suddenly kicks in violently and full power is restored. I fear water got into the maf as I have a K&N air filter siting right behind and to the right of the radiator.

So, I'm wondering if it was failing all along and water was the last straw. I need to get the codes pulled, so I dont have any idea if it has thrown a maf related code yet as the light is on for O2 sensors.

Does anyone have the page from the fsm so I can check it with a voltmeter and oscilloscope?

 

http://www.ncttora.com/fsm/2000/Repa...0Flow/insp.pdf

 

MAF sensors are very susceptible to dirt contamination with K&N air filters. It will usually kick out a MIL on with a P0171 (system lean). It will also have a hesitation off of idle.

Just pull it out and check the element on the sensor for dirt and oil contamination. Sometimes you can get away with cleaning them with a MAF sensor cleaning spray.

 

if your maf turns out bad ive got one off my 98 that you could have cheap