mthis

Hahaha dude that happened to me before lol. I bet u once u read the codes it will show MAF and A/F.

sflgator

Had the code read once @ an AutoZone already...doesn't "system too lean" mean that it's in fact sensing more air (from the high-flow BMC air filters) in the A/F mixture? I'm just wondering after I read & clear the code again (just bought the C-Reader V), will the engine light (code) keep coming back?

mthis

no it should not But if u baby the car for 1-2 months and just start beating on it then it will.

You will keep having this problem till the filter dry up alil. BMC+K&N put way to much oil on there filters.

lomita

too much oil,

Quadcammer

it sounds to me like you have a vacuum leak. The ecu can easily adjust about 20% by adding more fuel. However, if the leak is after the mafs, the 02 sensors see the additional air, but you hit a correction limit.

Check all your air intake connections.

TEXC63

This happened to me this weekend. I deleted charcoals and added K&N a month ago. This is the first time I have had CEL. I had a chance to push the car really hard on Sunday. I ran it up to 152mph and CEL came on. Light went off the next day after five or so starts. I just figured I exceeded the "normal" flow rates. I know I exceeded the pucker factor! Man these cars run good!

sflgator

I should have my C-Reader V code reader/deleter later this week, but I suspect I will see the same "system too lean" code (meaning higher air flow into the A/F mix). This second occurence of the engine light hasn't disappeared after ~ 10 engine restarts so far. I would like to see it disappear on its own and not return; thinking the ecu would adjust but maybe MB set the ecu with strict parameters on the A/F ratio and everytime it deviates from this, it sets off the code and the engine light goes on. It would suck if I have to continuously read/delete the code, even if I have my C-Reader.

sflgator

Another update guys...

I think Oliverk was correct after all (thanks man! ). Since I had the code come back again, I went to another AutoZone before I received my C-Reader V (which I just got today! ); had the code read and cleared again. Yes, it was the same "system too lean" code. So as I was talking to the AutoZone guy, we discussed the possible causes and he reminded me to check all the connections again for a possible air leak.

Although I couldn't exactly determine if there was an air leak, I did tighten up the metal hose clamps on the intakes just after the MAF sensors. After running the car for 2 days around town and on the highway (btw - blew away a shiny new red BMW 135i Vert that challenged me from ~ 70mph+, he he...don't think he was tuned as he started off before me and I downshifted in M from 7th gear to 4th and blew past him by ~ 1/8 mi. distance in the upper speeds ), I haven't seen the engine light again. I even just did a nice spirited run on my "private track" like I did the other day which forced a CEL, and I didn't get the CEL again.

At this point, I'm guessing that there was a slight air leak from one or both of intake tubes after the MAF sensors, and it wasn't caused by the BMC high-flow air filters themselves; I guess I just didn't clamp the intakes down tight enough. Anyhow, as long as I don't get the code again, it's all good.

Anyone want to buy a brand new, still in the package C-Reader V? j/k...I'll keep it just in case.

KCviper

That is encouraging news and hopefully the end of your CEL! I removed my charcoal, but have yet to switch to K&N's or BMC. This might provide the nudge......

RAW INC

I have been searching through the fourms trying to get the k&n filters to work without throwing a cel. After awhile i saw a write up on loose or bad intake manifold gaskets. I had deleted the charcoal filters and was just running with the stock paper filters with no problem for months but i guess the leak got worse and threw a code, took it to dealer with the cel on and they replaced the manifold gaskets under warranty. (that in its self may help some because the car ran perfectly, would not have know until i started searching and changing filters). as soon as i got the car back i couldn't wait to put the k&n's back in. It went without a cel for 3 days so i know i'm getting close. please keep up posted if the cel return again on you.

Even Money

I don't know that you need to run a K&N or BMC filter, unless you've really mod'd your exhaust and need the extra airflow on the intake side. Most issues are probably from the oil coating the MAF sensor, and all this hassle just to get 10 extra hp or so, maybe not worth it..

sflgator

But, in my case, it wasn't the oil from the BMC air filters that caused the CEL/engine light; it was most likely an air leak from one or both of the intake tubes just after the MAF sensors. If the MAFs sensed oil from the filters, then I believe a different code would arise; like "MAF malfunction" or something like that, not the "system too lean" code that I got.

And, yes, I think adding high quality high-flow air filters is definitely worth it, imho even if they only yield another ~ 5WHP or so.

sflgator

Sorry guys, another update, and this one isn't as positive...

I keep getting the engine light, and with my C-Reader V, I keep reading it and deleting the same "system too lean" code.

At this point, I was thinking that I still had some sort of air leak from one or both of the intake tubes where they get clamped down. So, I disassembled the 2 intakes, took out the BMC air filters, and then reassembled (with the BMC air filters) and made sure everything was perfectly tight and correct...still got the same code, but not when at WOT; it came on when sitting at a red light.

Any ideas guys? Thank you.

KCviper

Sorry to hear the you are still having issues. I'm not much help on this topic, but I feel for you and it's making me think twice before doing the same.....

Vegas_AMG_C63

This internal code is triggered when the ECU senses that the system is too lean. However it will only display a CEL once it decides that the condition is not a temporary and that an alert needs to be thrown. You may see for instance that at 15 miles after resetting the code, the system too lean code will be in the OBDII as a *pending* code. However the CEL will not trigger until a bit later, when the code moves from Pending to Current Status.

So the fact that it showed up on your display at a stop light is not significant in of itself. It's just waiting a certain length of time from when it first detected the problem. There is data in some OBDII readers called Freeze Frame which will let you know what the exact conditions were when the code was initially noticed (i.e. RPM, throttle position, coolant temp, etc). This may help narrow it down a bit.

System too lean codes usually have to do with either an intake or exhaust leak, a bad 02 sensor or an engine tune that's just not right. i.e. it's too lean and yes performance chips in modern engines like the C63 actually lean out the mixture on top, not add more fuel as many think. If you've got a tune in the car, I'd call the tuner to see if they can help.

I seriously doubt that the BMC filter can flow enough air to cause this light, but I do know that the AMG's are very sensitive.

sflgator

Thank you for all this insightful information. I was just thinking earlier today about contacting Bob @ RENNtech for some help. My C-Reader V does in fact have the Freeze Frame feature, so I may look into this.

Quadcammer

try this:

Get yourself one of those propane heater bottles.

Open the valve and move the bottle around the engine, specifically the intake tubes. If the engine revs up, you've found your leak.

sflgator

Update...

Neither RENNtech nor the dealer could find anything wrong...no air leaks, no MAF malfunction (all the values of the engine, AFR, O2, etc. are all "perfect"). They think it could be a faulty MAF sensor, but they're not entirely sure. So, I was told by my dealer to just wait to see what happens; may have to wait until the engine light (and "system too lean" code) goes on almost immediately after starting it up...i.e. the MAF sensor fails completely and then my dealer can back up a warranty repair/replacement with the proper documentation.

On a good note -- after some great conversations with both RENNtech and the MB Tech, everyone came the conclusion that the BMC high-flow air filters absolutely did not cause this CEL and neither did the ecu flash tune.

MRAMG1

I'll second that and raise you one

PS: To the OP glad to hear about your friendly dealer and tech. GOOD LUCK my friend.

sflgator

Thanks, and +1 on the "too much oil" b.s...both RENNtech and the dealer tech said definitely not too much oil on the BMC air filters.

Even Money

Well, you could attempt to isolate by putting the oem filters back in for a few weeks. Even though they say that's not it, you never know. FWIW, my dealer, who does kleeman installs, said not to bother with the oiled filters, K&N or BMC. His take was that they're not worth it, that the MAF is way sensitive. If you need to flow more air, get a larger intake. I read above that you don't think it's the MAF, but ask yourself, "when did I start getting issues?"....just after changing to the BMC filters.

Maybe your particular filter had just a tad too much oil?? Maybe it let something in that just nicked the MAF?? Just thinking out loud. I put a K&N in my '06 STi and it did flow more air, and you could hear it, but I think that's about all it did. I too took my charcoals out a few hundred miles back, and no issues. Just my .02 Good luck!!

KCviper

Glad your getting it figured out! I put K&N's on the Viper and you can certainly hear the difference in air intake!

sflgator

Thank you. Yeah, even the MB Tech said he did not think the oiled BMC air filters would cause this problem; he still thinks it's a faulty MAF sensor going bad (since the computer analysis shows perfect values for everything and my car is absolutely not "running too lean"). So, I'll probably leave the BMC air filters in for another few weeks, and if the code keeps coming up periodically as it's been doing (like ever other day but not every time I start the car), I'll switch back to the oem paper filters to see if that makes it go away. I also want to wait a while to see if the code arises when I first start the car; then, we'll know that the MAF sensor went bad. In the meantime, if it keeps coming back (which I suspect it will), I'll just keep reading and clearing the code.

sflgator

Last update (I hope)...

It was a leak in the intake manifold gasket; nothing to do with my high-flow cats, BMC high-flow air filters, or RENNtech ecu flash tune (but we already knew that )!!!!

sflgator

Ding, ding, ding...RAW INC, you're the winner!!!!