I recently replaced my factory air filter (2004 SR5 V6) with a K&N air filter. I had expected great results with the new performance filter, but actually got worse gas mileage and no noticable increased performance. Every other truck or car I have had, none were 4Runners, I have replaced with K&N air filters. They all performed much better afterwards.

When I took out the factory air filter, I noticed that it was a lot thicker than the K&N. What I mean is that the factory filter has a lot more surface area for the air to flow through. Eventhough I had noticed this discrepancy in design, I still installed the K&N based on previous experiences.

So after the installation, I took a long trip (400 miles) and measured the results. Not happy to say the least. So I called K&N customer service line and a rep. told me to diconnect the negative battery line for an hour to reset the computer. The rep. told me that the reset will allow the trucks computer to adjust to the new filter. I didn't believe the rep., but did it anyways.

I have not taken it on a long trip yet after the computer reset. Hope it works. I was wondering if anyone has had a similar experience or advice?

Thanks,
WhiteSR5Runner

what sometimes happends is that the K&N filter has that coating on it (the red stuff that you spray on) and it will get all over the MAF sensor. Thsi will now causethe MAF to underestimate the amount of air intering the engine. What i suggest, is to clean the MAF sensor. BE VERY CAREFULL!!!! Take the MAF out, take a q-tip with soem brake clean and VERY gently TOUCH the hot film/wire with a q-tip coated with brake clean. then just for fun, disconnect BOTh battery terminals and touch them together for atlear 2 hours. And then, go for a drive.