I noticed recently a low RPM bucking of the car when driving. This seems to happen around 2,000-3,000 RPM and feels a bit like someone abruptly taking their foot off the accelerator, and then returning it back to where it was prior.
Reading around, this seems to be a fairly common problem often pointing to the MAF (mass airflow sensor) on the vehicle. As they get used, they get dirty and their ability to measure accurately diminishes. Additionally, the housing they are mounted into on these cars are known to crack which allows excess (un-metered air) to be ingested causing lean run conditions.
You’ll know things have gotten bad when you start throwing codes (e.g. hard failure of the sensors), or other codes alluding to fuel trims exceeding their limits. Unfortunately, your sensor may be on its way out without any codes being generated at the time.
Often, cleaning the airflow sensor can help a lot. I tried this first, and although it seemed to get rid of the problem, it returned slowly a short time later. I was surprised this isn’t a unique experience by others as well — that once the sensor starts going out, no amount of cleaning is sufficient to get any further durability out of it.
Luckily, changing the sensor is fairly easy. The official Maserati part number is 180045 and carries a retail price of around $650. It however can be found at various parts suppliers for around $200.
The part itself is actually a more generic Bosch part and can be found even cheaper (including at local parts stores, Amazon, etc.). The Bosch part number is 0280218084 and can be found for about $110. Note that Bosch only sells this meter as a complete unit, and not just the sensor “cartridge” itself. If you find just the cartridge, it’s a clone. It’s simply not worth saving the $50-$60 going this route as they may be of questionable quality, and often the housing itself can be a problem.
To start the job, the first thing you need to do is remove the plastic surround on the right side of the engine bay.
Once the screws are removed, you will need to disconnect the right side hood strut. To do this, gently pry off the ball joint. Make sure to support the hood as you disconnect this as the weight of the hood may make it fall with just one strut attached. With the strut detached, you can remove the plastic surround, and then reattach the strut again.
First disconnect the electrical connector going into the MAF. The latch is facing towards the rear of the car so hard to see, but you simply need to press on it with your finger. You should hear a click, and then the connector should easily pull off.
The next step is to remove the two retaining clamps (RED in image below). Depending on whether this has been done before on your car, you may have different types of clamps already installed.
The factory uses one time use clamps. To release these, you will need a pair of needle nose pliers and gently try and spread the crimp until its loose enough to re-use. The factory sells these clamps for replacement, Part Number 190151, but I feel you’re better off simply buying a set of worm screw clamps. You need something approx 100mm in diameter.
Next, release the two clips holding the bottom of the airflow meter on (YELLOW in the image above). Be careful when releasing them, they have a tendency to fall. I dropped one and needed to use a metal coat hanger to fish it back out.
With the clamps removed, and the clips released, pull the joint between the meter housing (BLUE above) and the plastic tube (numbered 5 above) UPWARDS and towards the fender. I found this the easiest way to get things to pop free. Once you do this, the MAF housing should be easily removed.
With the old meter out, compare and inspect it against the new one just to ensure they match. One thing to note, is that there is what appears to be a foam gasket between the MAF housing and the air intake tube (circled GREEN in the diagram above) presumably to prevent air leakage at that joint. I didn’t have this part, and the one on my old meter was badly degraded/half missing/etc. I installed without it for now but will order one soon.
While the MAF is out, it is probably a good time to clean the throttle body and plate.
The installation procedure is similar, just in reverse now. It’s tricky getting everything to fit back together. The way I did it though is tried to mimic how I removed it. That is, place the intake hose loosely onto the throttle body and bend it upwards. Then slide the new MAF into its spot, also pointing upwards. By pressing downwards on the join between the two, things just popped in.
Once things are back in, put the hose clamps back on, re-attach the two clips, as well as the electrical harness. Finally, reverse the steps and reinstall all of the trim panelling.
At this point, you’re done and ready to go.