So about a week and a half ago my car started to idle lean.

First it was in the 15's
then the 16's and so on now its leaner than 18.

WOT is still perfect. I re flashed it and it didn't do anything. But now when I cruise it's up around 15 AFR.

IDK whats going on. The car feels the same. Anyone have any ideas or suggestions?


Also it may be unrelated but an exhaust leak is growing on my can and I can't find it. IDK.

 

cold air. it will run more on the lean side in the winter than in the summer. that's why alot of guys swap pulleys in the winter. i'm going from my 2.9 to a 3.1 so i don't blow the bitch up.

 

well, an exhust leak could be what's throwing off your afr reading....if it's near or before the o2 sensor you will be drawing in air there.....and possibly causing the lean reading/condition. I would fix that first, then see where you stand with the fuel condition, it will probably fix your problem

 

The thing is it got cold but its like 70 now. and its still doing it. I didn't think it would change it that much.

I thought maybe my 02 bung for the wide band was loos so it was letting in fresh air when I wasn't in the throttle but its fine. I cant even find the exhaust leak.

 

get under the car, while a friend holds his hand TIGHTLY over the tailpipe. if there's a leak, he should be able to hold his hand there pretty easily, and you'll hear the extra rush of air if there's a leak.

 

ok, here's a little trick to help find the exhaust leak.....turn the car on, let it idle...have someone cover the tail pipe up. Now with the tail pipe plugged up, the exhaust will need another place to exit....so it will go out the leak That should make it pretty easy for ou to find.

Like I said, I doubt it has to do with temp. Since you are fine at WOT (open loop) and lean cruising and idle (closed loop). Closed loop is when your car relies on your O2 sensors, so extra air will cause a lean condition. Open loop your O2 sensors don't contribute to the fueling.


on a side note...you would probalby want to give your friend a bunch of rags or something to cover the pipe with....since the exhaust will get hot pretty quick

 

^^^ beat ya to it.

well, half your post anyways

 

I know haha....damn computer froze and I had to retype to :-P

 

I will have to try that. I think it may be coming from my flex pipe.

 

Also another thing could ba an air leak after the MAF sensor, my car's been doing this lately since the turbo swap, found a leak on the pipe going to the TB, fixing that today hopefully

 

I'm having the same trouble and same A/F readings. My intake definately had a bad weld and was leaking. I tried to seal that, but still having issues. If you want to verify that just go out for a drive. Don't go wot, don't enter boost, but stay about 5 vacuum. You will hear a high pitched noise from the leak. Can't miss it if you are paying attention.

 

My car is running lean as well....up to l ike 17.5 a/f under normal driving...it goes away and comes back...I also have a leak in the intake somewhere....STUPID 2 piece intakes....My KN never had this problem...when I went back to stock, I had this problem, and now my fujita is having this problem...I hate 2 pieces

 

I found out that it was my flex pipe blown out and part of it was rubing my wide band. Now its fixed and I have a side exhaust.

 

Don't forget to either clean every 3k miles or swap dirty filters every 6k miles.
Also the fuel filter every 12k miles.

Those factors will make you go lean especially with the cold air now if not rectified.