Post #22294 of this thread:
Okay, many of you read this and replied with suggestions and stuff, so I thought I'd update. Wrap your noggins around this:
I ordered new couplings and t-bolt clamps to replace all the old ones on the intake hardpipes I have. They haven't gotten here yet, though.
I have always been a diehard Shell gas station user. I always insisted on Shell gasoline, and never had any reason not to. I had a bad experience with Sunoco gas, so I never used them again.
A few weeks ago, I started using Exxon, because the station near my office had a sale. They'd knock 6 cents per gallon off for supreme (93 octane) gas every Thursday. So I started timing my gas fill-ups to coincide with Thursdays. If I ever found myself short on a different day, I'd just put in $5 or something at some station to get me through to Thursday, when I'd fill up.
I never put two and two together to think my "system too lean" CEL code had anything to do with the timing of my switch to the Exxon station near my office.
So last night I was on my way home from the gym and my low gas warning light went on. I stopped in the Shell station by my house and filled it up. I kid you not, within 2 minutes of driving away from the station, the CEL light went away on its own and the car ran like new. No more stumbling under boost like a donkey having spasms, no more delayed throttle response...nothing but smooth running.
So that leads me to the conclusion that either the Exxon station I was using was mislabeling their 93 octane when they were really selling a lower grade, or they were mixing water (or some other filler) into their gas. (gah)
Now I'm not saying that the Exxon company does this across the board. But I do think that this particular station may have been up to some funny business.
So now I've got a new set of couplings and t-bolt clamps coming my way. I'm not upset about that, since I should have replaced the old ones a while ago. I do get a little razzed when I think about what could have happened. I could have potentially damaged my engine internals, in which case I'd be out a truckload more money.
Before anybody thinks that I just got a bad tankful of gas just once, I made the switch to the Exxon station about 4-5 weeks ago, and the CEL light came on about a day or two later. The CEL stayed on up until last night. It would turned off twice over those the course of those 4-5 weeks, but only because I made some other changes or when I reset my ECU by disconnecting my battery. The CEL would be back in a matter of hours.
So I guess my advice you guys is to pay attention to where & when you fill up and figure out if that may have anything to do with any codes your MSP throws in the future.