MAF Sensor help

[mcG]

my 3.8 engine has been misfiring a lot, 258 times on cylinder 4 to be exact. it's running way too lean thanks to a problem with the MAF sensor. it needs to be replaced.
first question: can the MAF sensor be replaced without taking apart the entire TB?
second question: my mechanic said nobody makes aftermarket MAF sensors, and he'll have to call around to the dealers to find one...any place i can find one online?
thanks for any info

[Injuneer]

First I'd be concerned about the diagnosis.... why would a faulty MAF sensor affect only one cylinder? The data from the MAF is used as the basis for fuel to ALL cylinders, so a problem with the MAF would likely show up in all cylinders.

How do you know that one cylinder is running lean? If you determined this from appearance of the plug, I'd say it was a good indication that you have a clogged injector on that cylinder. Given the way A/F is controlled, its not likely that a single cylinder would shows signs of running lean for any other reason - except perhaps in intake manifold leak to the runner on that cylinder.

Try moving the #4 injector to another cylinder, and see if the problem follows the injector. If it does, case closed. If it doesn't, check the ignition wiring for that cylinder. Again, since two cylinders share the same ignition coil (lost spark/direct fire ignition on the V6's) you only need to look at the wire from the coil to the plug for #4, and at the #4 plug itself for cracked insulator or other problem.

I'm no V6 expert, but appears from Chiltons that the V6 MAF simply bolts to the front of the TB.

Why would you want an aftermarket MAF? The stock one is fine. If you need a replacement, get it from one of the dealers that cuts us 50% discounts off GM list, ,like Jason Cromer or Dal Slabaugh.

[mcG]

thanks Fred, guess i wrote it kind of confusing in my post. it effects all cylinders, mechanic just mentioned to me about cylinder 4 as an example.