I can't seem to get rid of my check engine light indicating engine too lean. It started way back when the truck was new and I added a Borla exhaust. Dealer read the code way back when and cleared it. Blamed the exhaust. I keep clearing it once in a while by removing the batt cable, it comes back. I added a new magnaflow muffler using stock toyota tailpipe, cleared code, comes back - maybe not for a week, month, two months...but eventually it comes back.

Anything I can do?

Jeff

 

If this is code P0171 you can start by cleaning your MAF sensor.
http://www.4x4wire.com/toyota/mainte...tenancep5.html

I use brake cleaner instead of electrical contact cleaner because it works better (air dry thoroughly before starting the motor). Also be sure to reset the ECU by pulling the negative battery terminal again as you have been. If it fails to clear it you may need to replace the MAF sensor or possibly your front O2 (A/F) sensor.

 

Great, I'll give that a try. I had a K+N intake installed with the original exhaust when the first code appeared, so maybe this is what it needs. I removed that POS. Thanks, will try the cleaning.

 

Ok, with that little extra piece of info I guarantee that's what the issue was.

 

your exhaust won't cause the problem....ever!

the problem is most likely caused by the K&N kit, oil from the filter has gotten on the MAF sensor causing dirt to stick to it. Try cleaning the sensor first. Do a search, there are plenty of write-ups on how it's done.

 

x2 on cleaning the MAF

 

Okay that was quick and easy. I used Carb cleaner and some compressed air. Here is the picture of what it looked like before - what do you think? Notice the dog hair? I reset the ECU. Lets see what happens. Okay now who has a nice 30 minute fix for about 50 HP?

 

You really should have used brake cleaner like I mentioned because carb cleaner leaves an oily residue which can coat the wires and will bake itself on when the wires heat up (eventually it may force you to replace the MAF). You probably didn't kill the MAF by doing this but next time don't use anything that leaves a residue when it dries. You might want to buy some brake cleaner anyway and just clean it a second time to be sure it has been thoroughly degreased.

 

Fair enough, I'll redo it. I'm not driving it anyways for the week. Thanks for the input - what did you think of the MAF - it was hard to see if it was dirty until I brightened the picture up.

 

The MAF was definately dirty!
Those wires should be nice and shiny clean.

 

mmm the after math of what a k&n filter does

 

Yeah, never again. I had the CEL a few weeks after it went in. K+N blamed the exhaust, and Borla said it was possible with a combination of aftermarket exhaust and intake. I removed the K+N filtercharger intake and went to stock intake after about a year and I been driving around for 7 years with the CEL on and off thinking it was the exhaust. Hope this fixes it.

 

The K&N filters are fine on vehicles that don't have a hotwire MAF (like the 2nd gen 4runners that use an AFM). Using them on 3rd gens is just asking for trouble because they seem to shed oil easily and really don't filter well so all that gunk sticks to the oil and coats the MAF sensor wires thus your ECU throws a CEL when it gets bad enough. Let us know if the CEL stays off after you clean it with brake cleaner.

 

Wow! 7 years with the CEL on...... hopefully you can clean the MAF, if it don't work, you may have to replace it.......

BTW I've had nothing but sucess with the TrueFlow filter

 

x2 i spent a few weeks on yotatech looking for what filter to get and trueflow was the best

 

Used to be Amsoil was the best air filter, but now Trueflow has moved into the top slot. Both use similar foam construction and both will do just fine to get the job done, but I believe someone did a dyno run in the past proving the Trueflow the best. I don't remember which thread I saw that in?!

 

Well, it's back on again. I haven't cleaned it with brake cleaner yet so thats on the schedule for today. I'll reset it again. It seems to happen when I am running the truck at low speeds, on the beach, around town, etc. Longer trips, or when towing - it takes longer to come on.

 

Clean it with brake cleaner first and if it comes back again replace the MAF.

 

MAF is 151 bucks. Front 02 Sensor, which is actually a fuel/air sensor according to the parts guy (I have CA emmisions) is 250!

Ouch.

 

You can get a new MAF on eBay for alot less than that (the Toyota P/N is 22204-07010).
http://cgi.ebay.com/ebaymotors/4RUNN...01036189QQrdZ1
http://cgi.ebay.com/ebaymotors/4runn...01036697QQrdZ1

A/F sensors can be had for around $180 from www.urdusa.com if you end up needing one.

www.trdparts4u.com also carries OEM parts at discount prices.