95 Pontiac Trans Sport Mass Airflow

pontiac

#1

I’ve got a 95 Trans Sport that I’m ready to move along to its next owner. It’s in very good shape with 138k on the odo, and an engine that was replaced by Pontiac at 66,000mi. All that being said, it doesn’t run smoothly for beans. I’ve had the computer read a few different times, and it spits back a code indicating an issue with the mass airflow sensor. Friendly local mechanic sez it’s a $300 job, about $250 or so for the part and $40 for the labor.



My question to anyone who might know is this: Where is this thing, and how hard would it be for someone good mechanical aptitude and relatively little automotive experience to replace. If my shop is only charging an hour of time, it can’t be THAT hard to change, right?



So, anyone out there know where this thing can be found, a repository of knowledge for the 3.8 6-cylinder beast living under that hood, or someone who’s done it before?



Thanks,

Scott


#2

It’s located in the intake tract between the air cleaner housing and the throttle body and has a wire connector attached to the side.
They’re easy to change and here’s what it looks like.

http://www.partsamerica.com/ProductDetail.aspx?MfrCode=A1C&MfrPartNumber=8650001&PartType=473&PTSet=A

You could always try gently cleaning that thin wire element that you see inside. It’s also possible the wire connector could have scaled over so the simple act of unplugging it and plugging it back in may help.
Hope that helps.


#3

They are very easy to change. If you call around and price match a reman. can be found for under a hundred.Also sometimes if you tap on it while the engine is running you will hear it smooth out.


#4

The Auto Zone web site shows the MAF for $134.


#5

You may want to try cleaning your existing sensor first. Auto stores carry MAF sensor cleaner that you can spray on it.


#6

Ok, so let’s say this thing is crusted over, or junk, but either way, not working. Would it cause the engine to stutter and fail to run smoothly? When I drive it, it revs up and down as if it’s accelerating, then decelerating, very rapidly. If I STOMP on it long enough, sometimes it will suddenly burst into life and take off like a bat outta h@ll, but as soon as it shifts, it’s right back to the herky-jerky.

And, if that isn’t something that’s symptomatic of the MAF sensor, what else might it be?

Thanks for all the input!
Scott


#7

Yes, the MAF can do all of that. Unplug the MAF and go for a short drive to see if the problems disappear. If they do, then you know the problem is more than likely related to the MAF; either contaminants or scaled over connector…

After that, try cleaning it and see what happens.


#8

Well, now I know what I’ll be doing on Saturday! I’m really hoping that it’s something like this that is relatively easy to get at and hopefully fix!

Thanks for all your help!
Scott


#9

Ok, getting to this thing was WAY easier than I could’ve imagined. Sprayed the heck outta the wires, leads and connectors, etc… let it dry and took 'er out of a drive. The same stuttering and whatnot was happening, but not quite as severe. I pulled over after about a mile, disconnected the sensor all together, and the damn thing ran beautifully. GREAT, I think, it’s the MAF, $139 at the local auto place, done. Got the part, installed it, took it for a drive.

The new MAF solved all but about maybe 25% of the problem. It still stutters and sputters a bit, but drives smoothly after it works itself out. Not that I’m a mechanic, but is the next step the O2 sensor? I know it’s next in the airflow line, correct?

One other thing I noticed: The issues seem to happen more immediately after a shift, and once it’s been in gear a few seconds, it’ll kick over and be fine. Any thoughts on that?

Cheers,
Scott


#10

Rather than an O2 sensor I might be leaning towards the spark plugs or wires considering the chronic bucking and jerking problems you’ve had.

Rough running will soot up a plug and cause a misfire. In the old days one could take a high speed drive and “blow the cobs out” as it was called. Newer vehicles run much leaner and a misfiring plug will be more noticeable whereas on an older car it may be covered up.
Misfiring plugs can also damage or cause scale on plug wire ends.

If it were mine, I would pull a plug on each bank (easiest ones!) and take a look at them. If they’re blackish in color I would replace them and also examine the plug wire ends very closely to make sure there is no scale or corrosion on the ends. Even a light dusting of corrosion can cause an ignition miss.

As a matter of fact, back in the mid 90s GM had some plug wire failures on the 3.8 engines and even applied a good-will warranty to certain models. I’m sure this campaign is long dead and gone by now and may not even apply to your model.
Some of the models with the 3.8 used metal shields that clamped over 3 or 4 of the plug wires to serve as heat shields since the plugs are located so close to the exhaust manifold.
Misfiring plug causes a spark to jump through the boot to the metal shield, which then jumps to ground.

Considering that history I would sure consider replacing those wires if they’re the originals. Hope that helps.