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I just happened to see this today 😄 "This is not parallel parking, Christine; this is magic!" Cagney and Lacey, season 7, episode 20. May 2, 1988

These are views of the socket half of the connection.

Anthony, thanks for the cluster connector info.

I wondered about the terminology used initially because the throttle assembly removal is a whole different process. The only thing that could possibly be calibrated in some fashion is the housing itself. The casting has a brass ring pressed into the throttle body side which leaves an open slot that the incoming air passes by. The passage for the sensor is offset from main air inlet and is less than 1/2” diameter. The other end of the passage terminates in the slot mentioned above. It is a high speed air flow area so pressure would be low to draw the air past the sensor.

Thanks for providing those tables and the extra information. I've never seen those before, and they aren't in the FSM, which is very vague on how it works. The only thing it says is the reading should be 4-7 at idle. In another section it says 4-12 🤷. The previous version of this engine, the LG3 for '87, had the MAF in a removable section of the air duct, closer to the air cleaner housing. I've replaced those many times by themselves because, well that was pretty much the only way, since it wasn't even near the throttle body. I guess there must be some advantage in precision of the readings by moving it closer for the LN3 in '88. It's possible that there was some miscommunication in the making of the training video, because after some searching in the FSM, I found this: It says to not remove the throttle body itself, just the aluminum MAF housing. I wonder if they do some kind of test during manufacture, on a flow bench, as you did, then make some kind of adjustment by pairing them up with a different housing or MAF, or even simpler--just discard assemblies that don't meet specs. I have read that Porsche suppliers do that, and the ones that are slightly off get sold to aftermarket supply houses 🤭.

To be fair, it is possible to alter the airflow past the sensor by doing some polishing, drilling, grinding or other operations to change the flow path. It is possible there is some form of calibration available, but in the overall scheme of the system, it doesn't seem to matter as long as it is close. The vin C engine uses a separate casting that bolts onto the throttle body. The later 90-91 vin L engines, the tuned port style, have an integrated MAF and throttle body, but the frequency response is the exact same as the earlier model. Both of these types use an indirect flow path with a separate passage for the sensor. The sensor is not exposed to the main airflow like used in some other styles of MAF's. In the course of more than 25 years, I have used four different MAF configurations and even mounted a stock Vin C MAF on the inlet to a turbocharger, and they have functioned acceptably with the stock ECM. Yes some have involved other tuning in the Prom, but that is because the operating parameters of the engines has been substantially different, usually due to some form of boost.

As an owner of numerous Reattas for over 15 years and close to 300000 combined miles I have replaced numerous MAF sensors and not the throttle body. Like Ronnie says, not worth cleaning the MAF just replace. Also on my recently purchased 199 Buick Regal I replaced the MAF sensor on that one as well without replacing the throttle body. No issues and also after replacing Ignition Module, plugs and wires car runs like new.

I wonder how much it matters. RockAuto sells the MAF both ways. You can buy the complete assembly or just the sensor. I have changed just the sensor a couple of times without problems. My experience has been that they start out going bad by causing an erratic idle when you come to a stop with the transmission in gear. Cleaning didn't help but replacing it with a known good used one cured the problem. I never replaced the sensor and the throttle body as a unit. I have a friend who owns an auto parts store. He owned a big Buick with a 3800 back in the '90s. His MAF went bad often for some reason. When it went bad the motor would hardly run at all. We didn't know that the engine would run better if you unplugged the bad MAF. He carried a complete MAF unit and tools in the trunk. He would swap it out on the side of the road. He couldn't buy just he sensor without the throttle body from the warehouse he got his parts from. He was told that they were only sold as a calibrated unit like you mentioned

Hal, here is a list of Hitachi MAF sensor flow rates GM assigned the MAF sensor output frequency in a stock 3800 vin C chip... MAF Vs. Output Frequency Table 1 kHz gm/sec 2.00 3.19 2.13 3.53 2.26 3.94 2.39 4.38 2.52 4.81 2.66 5.31 2.79 5.88 2.92 6.41 3.05 6.97 MAF Vs. Output Frequency Table 2 kHz gm/sec 3.05 7.44 3.18 8.06 3.31 8.81 3.44 9.56 3.58 10.31 3.71 11.31 3.83 12.50 3.97 13.69 4.10 14.88 MAF Vs. Output Frequency Table 3 kHz gm/sec 4.10 13.9 4.23 15.1 4.36 16.5 4.49 17.9 4.63 19.3 4.76 20.8 4.89 22.4 5.02 23.9 5.15 25.4 MAF Vs. Output Frequency Table 4 kHz gm/sec 5.15 25.43 5.28 27.07 5.41 28.55 5.54 30.19 5.68 32.16 5.81 34.13 5.94 36.09 6.07 38.23 6.20 40.20 MAF Vs. Output Frequency Table 5 kHz gm/sec. 6.20 41.00 6.33 43.25 6.46 45.75 6.59 48.25 6.73 50.75 6.86 53.75 6.99 56.50 7.12 59.50 7.25 62.75 MAF Vs. Output Frequency Table 6 kHz gm/sec 7.25 62.5 7.38 65.8 7.51 69.4 7.64 72.7 7.78 76.3 7.91 79.6 8.04 83.2 8.17 87.2 8.30 91.2 MAF Vs. Output Frequency Table 7 kHz gm/sec 8.30 91.2 8.43 95.2 8.56 99.3 8.69 103.3 8.83 107.8 8.96 112.4 9.09 117.4 9.22 121.9 9.35 127.0 MAF Vs. Output Frequency Table 8 kHz gm/sec 9.35 126.3 9.48 131.0 9.61 136.4 9.74 141.8 9.88 147.1 10.00 153.2 10.14 158.6 10.27 164.6 10.40 170.0 As you can see they are "close" to your test readings. Sorry you couldn't find any 3.0" MAF sensors at your junkyard but I do have one sitting here I can send you if you want it. -ryan

This is the MAF chart I received from GM Tuners many years ago. You can decide if it is discrete enough to require it to be pre calibrated. I can only speak personally about replacing MAF sensors, but I do not know of anyone that changes that entire assembly, despite what it says in the FSM. If you take apart the TB and MAF assemblies, there is almost no machining done after casting and the passages are as cast. I have run a couple dozen sensors on my flowbench just to get a sense of the range and if they are operational. The calibration, if there is any, consists of the sensor, the passageways, the laminar flow over the sensor and the ECM. This is the way I understand the system: The sensor has a heating element and a thermistor to read the temperature. The ECM sends a pulsed signal (probably ground) to maintain the target temperature to infer that actual mass of the air. The frequency listed in the chart is the pulse I am referring to. I am pretty sure the air temperature sensor in the air box is needed to precondition the required heating range. The MAF reading is used in combination with other inputs for the PROM to generate the LV8, or engine load figure, which is one axis of the main spark timing chart. It looks like this old chart won't open, darn it LN3 MAF chart.pdf

All these things have in common the BCM connector. They also have in common ground G103, which is attached to the cylinder head below the generator (alternator).

After driving the Regal for about 3 weeks and a bit over 1000 miles I have had to do some "fine tuning". Started with an Idle Air Control, Then on to a Mass Air Flow sensor. Then yesterday I stopped in at Gibson's a local You Pick yard to get a back up battery. [This was after lunch with 2 Seater] Came out to the car and it wouldn't start. It would grind but not start. So I first checked fuel pressure, that was good. Then said to myself " Either Ignition Module or Crank Sensor". The obvious easy answer was to start with the ignition module. I know I was at Gibson's but I had a back up in the car [always carry extra parts and tools]. Had it swapped out in about 15 minutes. Hit the key and it started. I decided that I needed to do a tune up and checked my inventory of Reatta replacement parts. The Regal is a Series 2 so I knew the Delco upgrade I had done on the Reatta would give me pretty much what I needed. I checked online for spark plug wire length and plug number and checked what I had in inventory. Sure enough I had a wire set that was close in lengths and the correct number plugs [#14]. Called up Kendall [my mechanic friend] and invited myself over for a tune up party. Plugs and wires and clean up the plate under the ignition module. About an hour later the old original plug wires [in poor shape] and the old plugs [badly worn] were out and the new ones were in. Drive home was much better as the acceleration was noticeably improved.

Glad to hear you're getting back into the game Ronnie! My BIL has a "fox" Mustang convertible. He likes it a lot. Also my first car was a '66 Mustang...

After long term inactivity and unknown storage conditions, the first thing I would check are the battery connections, ground and B+ connections inside the plastic boxes on the passengers fender and at the engine. Each of the battery cables consists of three terminals on the other end. Then move on to the ECM and BCM connections. Simply unplug and reconnect to get a new fresh connection, terminal spray cleaner optional. Lots of those items operate on lower than system voltage so connections are everything. Of course the wiring itself is subject to damage from vermin, but start with accessible connectors.

Spent some time this weekend with my friend Gary who has owned Mustangs all his life. He drives them and races them. He has convinced me that my next "weekend car" should be a '99-'04 Mustang,. They are reasonably priced and super easy to get new, used, or aftermarket parts for. They are simple cars compared to a Reatta, both mechanically and electrically. Gary knows Mustangs like the back of his hand and he's willing to help me work on one if that's what I get. That means a lot since Gary has a lift in his garage and a barn full of Mustang parts. 🙂 I've never been a Ford man but now I've got my eye pealed for something like this to replace my Reatta.