Cameron58

I have a '99 Jeep Cherokee Sport, 6 cylinder. The engine dies just about ever time I slow to a stop, sometimes dies when driving if I'm not accelerating, and the car bucks and jerks. I want to clean the MAF sensor. I have located it - black, approx 2" x 3", has an "L" shaped rubber tube going from the bottom of it into the engine. So, I removed it, and all I can see to clean are the prongs the plug connects onto. There is a seam around the top of the sensor where I could probably stick something in and pry off the top. Is the top supposed to be removed, or will trying to pry it off ruin the sensor? Is the part I need to clean inside the part I removed? If so, can it be cleaned, or do I need to buy a new sensor? Thanks.

Quezzy

Cameron58

Thanks for the response. Yes, I do have a can of mass air flow sensor cleaner. MY question is about how to go about applying it to the sensor when the component seems to be sealed.

Quezzy

If you pry it open then you might as well buy a new one. The sensors are very sensitive.

Cameron58

What if I were to lift the top just enough to get the straw for applying the cleaner through. Then spray the cleaner into the closed component? Or how about sticking the straw up through the nipple on the bottom that the rubber hose pushes onto? Do you think spraying the cleaner into the closed component might clean the sensor, or is it more likely to destroy it.

Quezzy

The sensor isnt in the sealed section. You spray anything on the c-board you might fry it.

Bustedback

There is no mass airflow sensor on an XJ, only a MAP sensor and you can not clean it out. What makes you think the MAP sensor is the problem? Check engine light on?

3278

Yeah, I would back all the way up on the troubleshooting front. If it's acting like this, it's got to be throwing some check engine codes: have you had it on a code reader? What did you find out?

Cameron58

Yes, the check engine light is on, and the code indicates a problem with the manifold absolute pressure sensor. Any idea how to fix that?

3278

Sometimes this turns out to just be a vacuum line, at the MAP sensor and throttle body, or sometimes bad EGR valves or clogged or leaking air intake. If it's not those things, you can diagnose it electrically, which always seems like a good idea until I try it.

[In general, this is a good resource for sensors, I've found.]

Ultimately, it often comes down to cleaning what's not broken, and replacing whatever might be broken. I'd love to give you a simple, clear flowchart that'll lead to a working Jeep with no time or money wasted, but in my experience, that comes at the end of several decades of experience. Which I don't have.

Bustedback

What year is this XJ? Look for a cracked vacuum line if it has the hard plastic lines, or a rotted rubber hose or elbow. It could be a bad sensor too, but check for vacuum leaks and damaged wiring to the sensor before replacing it.