I installed a set of B&B Bullets last weekend and love the sound. However a couple of days ago as I was driving the check engine light came on. the car continued to run fine and it was today before I could get to the dealer. The tech pulled the codes which indicated that the engine was running lean. Both banks. We discussed the new exhaust and the tech does not believe that would cause the condition. We also talked about the my Halltech intake but he indicated that neither part should be causing the problem.

Now, what I didn't mention to him was that I had removed the MAF screen and installed a 160 degree thermostat. I didn't mention the MAF because I had done that 20K miles ago and never had a problem, and the temps in the car only decreased about 10-15 degrees (both oil and water). I am running a stock tune.

So I guess my question is even though any mod I've done would not cause a problem by itself, have I somehow created a combination of mods that would cause a lean condition?

MY MODS:
Halltech Intake
160 Deg. Themostat
MAF screen removed
B&B Bullet exhaust

The tech also did a search and found a GM notice that dirty injectors could cause the problem. However, he said my car didn't have enough miles on it to have dirty injectors (24K highway miles).

They were short handed today so I agreed to bring the car back on Monday. The tech said that it was ok to drive the car but to just take it easy. He reset the engine light. I added a bottle of injector cleaner on the way home and, so far (about 75 miles of driving), the light has not come back on, although I expect it to at any time.

Any suggestions or recommendations?

 

It's the MAF SCREEN.Have heard of this issue before when that's done.Put it back on.

 

Probably the screen. Did you disconnect the battery during your mod installations?

 

mostly likely you have a leak after the maf. make sure all clamps are tight but not too tight to deform anything.

descreen maf with stock tune will cause problems, you may not see it unless you were data logging.

http://forums.corvetteforum.com/show...ght=maf+screen

 

Same thing happens all the time on Fuel Injected Harleys. You can change the intake or the exhaust on the stock tune, but if you do both, good chance it will be too lean. Change just one and your really not changing the airflow through the engine that much. Start with putting the MAF screen back in and checking all intake connections for tightness. Drive for a few days, sometimes the computer can adjust to a little increased airflow.

Another thing to look at is the MAF hot wire. The resistor that gets red hot right in the middle of the MAF sensor. Take a close look at it and make sure there is no fuzz burned onto it. I've seen aftermarket air cleaners that shed a little fuzz and gets burned onto the sensor. The sensor then reads less air than is actually flowing and makes the engine run lean. If it is fuzzy, carefully clean it with electronics cleaner off the car. Some parts stores even have MAF cleaner spray.

Putting the screen back in straightens out the airflow over the sensor. On the stock tune you need that airflow to be just as intended with the screen in place.

 

Someone correct me if I am wrong but if you remove the screen, wouldnt that increase airflow? U may be getting the check engine light because the computer detects the increased airflow and it never calibrated the air/fuel mixture to the new flow. Did you disconnect the battery? If not do so and let the computer calibrate. Try that and see what happens!

 

Guess I don't see why you'd want to remove the MAF screen. Whatever tiny performance increase you'd gain (debatable) doesn't seem worth the increased potoential for FODing out your MAF or worse. No way you'll ever feel a SOTP difference by removing the MAF screen.

It sure is a free country though. What the hell do I know. Hope your issue gets resolved.

 

Maybe the MAF screen?