Have had a persistent check engine light. The shop cleaned sensors, checked vacuum.... Checked injector pressures. It did get a tune up and fuel filter. I got about 25 miles since the last clearing of codes. A different shop got a more detailed code. Bank 1 Lean.... I did put in a K&N filter before this part started. Did this cause the issues? None of the shops seem to think so. Ideas?

 

Take the filter off...and see.

 

I agree with Randy. I’ve had so many issues with customers K&N filters because the oil gets inside the MAF sensor and inaccurately meters the air reporting to the ECM hence why the lean codes occur. That’s the first step, getting rid of the K&N. The second step is to clean out the MAF sensor with brake cleaner (I’ve done hundreds with no issues) or MAF sensor cleaner. You must spray vigorously up inside that tube where two resistors reside at following a hefty dose of compressed air. It’s preferable to get the codes cleared then drive it awhile and see what happens.

 

I, too, found the KN filters dirty the MAF sensor: return to the original (or run a few miles w/o filter); clean the MAF sensor; check for tears in the air tube; clean the throttle bore and plate; make sure the seal is secure when you reinstall the air tube; run a can of good fuel system cleaner through a tank (Gumout's SeaFoam look-alike is my favorite, but any of the better Lucas or SeaFoam should do); reset the codes . . . and report.

These are all things you can do yourself with a couple of screwdrivers, a 10mm socket wrench, a towel over the fender, and patience and a clean rag . . . may need the shop to read the codes, or your local parts store (better, buy your own code reader -- pays for itself the first time you don't have to take it to a shop or can tell your shop your problem). For Forum readers to better help you, you should let us know what model, what year, how many miles. . .

 

Thanks to Randy, Addicted and Jim. We always have to ask ourselves, "what changed".... Well, if taking it out works, this is the first time that i can say that i've had a problem with K&N. I've done the simple drop in AND the larger kits. My Mechanic did clean the MAF and said he doubted it was the filter. What i am seeing is that even though this is a Ford Jaguar, it's very touchy. Quite sensitive. I had already decided to put back the old filter, as i save the good ones. I'll clear the code and see what happens.
Be well.

 

Tell ya what. This computer tells the car that it's running lean and down goes the fuel gauge....

 

The computer tells the car it is running lean, so the ECU enriches (needlessly)

 

Yes....

 

I've found a very small leak can cause lean codes. I have a thread about it. Turned out to be air leak around one injector. Could not hear with auto stethoscope. Didn't find until used a smoke machine. I have a thread on how to make one.

 

Thanks. I did change the filter and reset the code. I really think that this is a fuel situation. When i start it up and drive, it's good around town and doesn't get cranky until i start driving in the 45MPH plus range. The shop said that they changed the fuel filter. Maybe there's a partially plugged screen or something that is starving it for gas. If i make a stop for a few minutes and resume my errands, it acts okay, until i start driving over 45. The light hasn't come back on as yet, but i am sure it will, soon.