check engine light

[ginkof]

I got a check engine light which ended up being a lean code.... i was wondering why this would have happened... I have a milltek full exhaust and a carbonio intake. I dont have any ECU upgrades... I have had these mods on my car for quiet sometime with out a problem. My car is a 2004 S4 with 37k on the clock... any ideas? fuel filter maybe?

My friend just installed the jhm on my car.. its awesome! definitely get the stiffer reverse spring for anyone thinking about it... its worth the $5

[ChronicTeutonic]

Speaking from my knowledge of carburetors (own a MGB with dual carbs) free flowing intakes and exhausts will definitely cause a lean condition. In the carburetor world you have to mod the jet/metering needle to rich up the mix.

In the FI world the ECU should adapt to these changes but there could be other factors limiting the adaptation. You could be "out of range" in terms of the factory mapping. The fuel injectors may not be able to deliver enough fuel to compensate. You could have a clogged fuel filter limiting supply to the fuel rail which is now showing up since you have to deliver more fuel.

I guess you could check to make sure that after market intake isn't leaking causing a lean condition? Maybe try the stock filter box? Dump some money into a ECU coding that can handle the freer flowing system you've got? Just some ideas. Where is an engineer when you need one (Lugi20?)

[ironchef1369]

I got a check engine light which ended up being a lean code.... i was wondering why this would have happened... I have a milltek full exhaust and a carbonio intake. I dont have any ECU upgrades... I have had these mods on my car for quiet sometime with out a problem. My car is a 2004 S4 with 37k on the clock... any ideas? fuel filter maybe?

My friend just installed the jhm on my car.. its awesome! definitely get the stiffer reverse spring for anyone thinking about it... its worth the $5

Hey just wanted to ask you about this post. I know it was a long time ago, but I'm running into the same lean code issue with a nearly stock car. Its intermittent, but pretty predictable when the gas light comes on. I thought it was just that, until the other day on a full tank, the light came on again. Did you ever figure out what was causing the problem? Thanks in advance.