Idles better with MAF unplugged?

[chris070780]

I unplugged my MAF today while the truck was running and it idled so much better with it unplugged. Is this a sign that my MAF might be bad? I have a random check engine light after driving. This is just an off-road beater explorer so I am not too concerned with it, but I am curious. I know when I unplug it the computer goes into limp mode, so it really seems strange that it idles better with it unplugged. I have cleaned MAF and no change. Would you guess bad MAF?

 

[92exp4x4]

Possibly, but there are many things going on at once. In limp mode its running at preset values, so its very possible that it could run better. Other guys have said the same thing here before.

Have you pulled the codes? I'd be curious to see whats stored in it.

Throw a carbed 302 in it!

 

[billybob3358]

mine done the same thing and all it was was a vacum line come off u can run it with it unpluged it will just make u get crappy gas milage

 

[chris070780]

Funny you mention the vacuum line as I found a large leak from one of the lines and fixed. Still doesn't idle any smoother, but I didn't try pulling the maf connector after I repaired the line. I just need to stop being lazy and pull codes, as after driving for a short time it doesn throw a code. My TC is not locking up (its does when I manual ground the TCC wire) I have suspicion it is my MAF sensor. TPS has been replaced and cruise control works.

 

[arco777]

Pull CEL codes (Autozone does it free) and check for "MAF out of range" accompanied by rich/lean condition codes. Those often indicate a failing MAF.

A bad MAF can cause all kinds of trouble. When you disconnect the MAF sensor, the computer switches to using manifold absolute pressure (basically like the older Ford Speed Density EFI) to run the motor. You can safely drive the car with the MAF disconnected but you may notice slight performance gains and smoother operation with a new MAF. Speed Density systems were not good at adapting to improved intake and exhaust flow from aftermarket parts. Mass Air works a lot better for this and your computer will be happier.

Junkyard MAFs are hit or miss so I don't recommend them. A remanufactured MAF at a parts store will include the housing and usually runs $80-120. Ask for a warranty if possible!

 

[Joe Dirt]

Speed Density systems were not good at adapting to improved intake and exhaust flow from aftermarket parts.

I know what you're saying, and yeah, after a point, but until then... I beg to differ! 11.90's on a junkyard Explorer motor with shaved heads, ported lower, a stock SSV cam, Cobra rockers, FMS headers, H-pipe and Flowmasters pushing 3.73's (Sorry, I couldn't resist posting my Mustang)

...but anyway, before you buy a MAF from AutoZone after they read your codes, bring the codes here and let us have a peek at them since you may not need one.

 

[rhauf]

i had that problem once (ran bad with maf plugged in, ran good with it unplugged) turned out there was a tiny piece of fiber from the air filter caught in the "hairs" of the maf. take it out and make sure it's clean.

 

[rickybobby]

I know what you're saying, and yeah, after a point, but until then... I beg to differ! 11.90's on a junkyard Explorer motor with shaved heads, ported lower, a stock SSV cam, Cobra rockers, FMS headers, H-pipe and Flowmasters pushing 3.73's (Sorry, I couldn't resist posting my Mustang)

...but anyway, before you buy a MAF from AutoZone after they read your codes, bring the codes here and let us have a peek at them since you may not need one.

Beautiful mustang joe. the engine bay looks just like the last job i did before i quit the muffler shop. i got to put a set of hooker tuned headers and a custom x pipe on it.