My check engine light keeps coming on. I checked the code and it says "system too lean (bank 1)" Any ideas as to why this is happening? The only engine mods I have are DC Sports 4-2-1 header, Otto racing exhaust and a SRI intake.

 

i would see if they recomend changing any sensors....

 

Do you have any exhaust leaks?

 

I checked once already and haven't found any. Ill check again though. I also checked to see if the intake had a leak, and everything looks fine there. Before the car warms up it idles at 1500 - 2000 RPM. Once it warms up it has a slightly rough idle. Drives fine though.

 

did u ever get ur ecu adjusted for the extra air flow??? lean is mean and fast but to lean will burn up ur motor.... also check ur injectors they might b clogged a little bit

 

The ECU monitors air fuel ratio(AFR) or mixture with your first O2 sensor. It adjusts as needed by adding or removing fuel in the form of turning on the injectors for a longer or shorter period of time. System too lean is the inability for the ECU to add enough fuel to keep the AFRs at the acceptable levels. This can be caused by several different things. The sensor might not be working correctly, the injectors may be clogged, the fuel filter may be clogged, the fuel pump is going bad, there may be an exhaust leak that affects AFR readings, and a few more that I can’t remember off the top of my head. Do the obvious and less expensive first. I would replace the fuel filter and take the car in to get the professional injector cleaning service. Go to a shop that uses something like the snap on motor vac system to clean the injectors. Something else to look at after all of these is the MAF(mass air flow) sensor and the TPS(throttle position sensor). Good luck

 

Could a SRI throw off the Mass Airflow Sensor? A friend of mine said that an intake and header could cause that, but I dont really see that happening.

 

Well, I have an AEM CAI and DC headers and never had any problems. I guess it could be possible for the added air flow to over power the fuel system, but rather hard to believe. The only way I can see that happening is if your injectors are clogged/dirty. Your ECU is constantly learning the MAF signals and accommodates for them. At wide open throttle(WOT) your ecu normally goes into an open loop state where it no longer monitors O2 sensor readings and it will go off a default table for fuel delivery. That is when I would expect the system to run lean, but since it is in open loop and it is ignoring the O2 readings, this should not through the lean system code. Now, I have heard of over oiling the filters causing the MAF sensors to get dirty or even go bad. That I suppose can cause this problem. However for this I would expect it to throw a bad MAF sensor code, but still a possibility.

I still think the problem may come from the injectors or fuel system.

 

Agreed. I am going to put a new fuel filter on this weekend. If that dosn't fix it im going to have the injectors flushed. Hopefully one of those will fix it.

 

One other thing to look at is if the ECU is actually working correctly. I forgot about that one and someone else has a similar issue. That is what it turned out to be. When you figure it out be sure to let us know. it helps in troubleshooting others problems. good luck.