Engine System Too Lean

System Too Lean

I replaced my TB w/ an overbored TB and the CEL went on. When I read it w/ an OBD reader, the error code was "system too lean".

Does anyone have any suggestion to fix? (except for taking the CEL out)

Whered you get your TB bored out at? Probably could be because of the butterfly valve. Not sure to be honest. The guys on 9th gen got theirs done from maxbore.com and no one has had problems.

I bought it from SkyAce2004. He parted out his car.

I read in another forum to clean the TB & the MAF sensor. I'll try that this weekend.

you should ask skyace
maybe you need to have a fuel management system for the a/f ratio?

Make sure you reset your ECU by unplugging the battery for a min.

He had an Emanage Ultimate, but he said the CEL stayed on.

I tried, it did not work.


I have an emange blue that I have not installed yet. I will do some cleaning and install new cams and the emanage. And hopefully get it tuned. I'll see what happens from there.

well when you add more air... and the same amount of fuel... hmmm

Ya you're right. I just did not expect that it would be too lean to turn the CEL on.

install a wideband and find out just how lean youre running. the computer should adjust accordingly, but for some reason it cant now. i hope youre running 91 and just put putting around... a lean condition can, and usually will, damage your engine. i know this from experience.

Sorry I did not reply to your PM earlier, but you know im on vacation. When I installed the TB in my car, the CEL was also on, but when I had it read, it said something about an oxygen sensor being bad in my exhaust. However, I never did anything about it because I had the wideband installed and hooked up to my emanage for fuel management.

You are adding more air to your engine now that you have a bigger throttle body. the butterfly valve fits the body perfectly. Maybe a sensor on the throttle body is bad. I dont wanna stick you with something thats going to give you problems, so if there is anything I can do to help ya out, let me know what I can do.

did you ever get rid of the cel kudkud?

No not yet. This is what I observed. When I am driving on the highway it does not come on, but when I hit stop and go traffic, it comes on then I have to reset it again.

hmmm... what is that sensor that only kicks in on the steady rpms or whatever... i think i read that somewhere...

let me go revisit some posts and try to find it

---- 6:10pm ------

OK, I think I found the cause. When we installed the new TB, we did a coolant bypass. I reconnected the coolant lines to the TB and now the CEL does not come on anymore. Not in 2 days, anyway.

--- 11:50 PM ------

I take that back. It went on again. The search is still on.