i have had my evo since august, has always held perfect 14.5-14.7 AFR at idle. a little over a month ago i installed an ETS licp and a 3.5" intercooler, but the AFR was still the same, 14.6-ish. just in the last week, it has been idling around 15.6-16.0 for some reason, does anyone have an idea as to why? is the car finally getting used to the mods, or is there something wrong

 

Probably dirty maf take it off and hit it with some CRC Maf Sensor cleaner. Or it could be your wideband. Hopefully u stay on top of your boost leaks and ran atleast one test sincE getting the car.

 

Check the MAF. You're not running a K&N filter are you?

I had my wideband read high once and my DP had came loose and I needed to tighten it back on. Check that and see if its the issue GL.

 

i did add an open air filter the week i bought the car, but it still has read fine until now

 

If it is an oiled filter I suggest getting rid of it. To many horror stories about them annihilating the MAF from all th oil collecting on it then dirt getting on it. Most MAF sensors when you shut the car off get rather hot to clean what contaminates could be on the screen. The oil would just bake on it.

I hope that this helps check for leaks around your DP and even a bit after the sensor. I know how frustrating it can be to have it reading high.

 

EXHAUST LEAK! prob somewhere around your 02 housing

 

Had the same problem

 

cleaned MAF sensor today, still idling at 15.6 - 16.0
so that isn't the cause

the MAF sensor on my celica on the other hand looked like it had been swimming in a sewer

 

checked the downpipe, and where it meets the test pipe was slightly loose, went ahead and tightened that up and that seemed to solve most of the issue

thanks for everyones help.

 

no check around the mani,turbo,02 for anything loose that is causing a small leak

where is you a/f sensor?

 

o2 sensor is futher upstream not down...if it's not a maf issue then the o2 housing/downpipe should be your culprit

 

You fill up on different gas with more ethanol content?

 

nah, shell 93 always, i never change that

i checked up there too and everything seemed to be snug, perhaps i just need a tune worse than i thought, i did add a bunch of air flow mods

i'm not exactly sure because i bought the car with the wideband installed, going to have to do some searching to see where its at

 

Pretty sure that is what the cause is. I have heard of this happening before. A tune is always nice you might as well get it tuned for safety and power!