Late model 2nd gen MAF swap how-to
by Mike Mohr

Disclaimer:  *The following will tell you how to install the larger MAF from a later model (93-96) 1.9l Escort into a 91-92 and get it to work properly.  It's very simple, but I will not be held responsible for anything that you break or if anything happens to your car.  Furthermore, the MAF is a very sensitive part in making your car run correctly, so after doing this swap it may turn out that it will run worse.  If this happens just put everything back to how it originally was.  Again I won't be responsible for anyone's cars getting messed up from this!  Now on with the swap.

*Update*:  New information has been found since I originally wrote this.  It appears that most people actually do not need to switch the sensor on their MAF to get it to work.  The MAF that I got happened to be a '96 model, which is why it didn't work right with the sensor on it ('96 use OBDII as opposed to OBDI on 91-95's).  So theoretically you can just get the large 93-95 sensor and stick it on your 91-92 and it should be OK.  I have also heard that if the 93-95 sensor won't work on your 91-92, then you can get the ECU from the 93-95 car and use that to make it work correctly.  Of course not everyone's experience will be the same, so mod at your own risk.
First off, you need to find a MAF from a later model 2nd gen.  I believe all 93-96's had the larger MAF, but I may be mistaken.  Here is a comparison of the new MAF and old MAF so you know what to look for:

2mafs.jpg (53515 bytes)

2mafs2.jpg (62493 bytes)

The new MAF is on the right, and the old one is on the left.  Notice how much bigger the newer one is.

 

Now comes the actual work. 

This part of the swap may or may not have to be done.   There are some instances where the sensor will work fine without swapping.  I suggest connecting the new sensor and driving around first before you do the next step.   The sensor I got had a different plug which makes me think it was from an OBDII car.  You NEED to do the next step if this is what you got.  Now if you get a sensor off a 94-95 (OBDI) you *should* be able to just stick it on and it will work.   Try and see.

First I recommend disconnecting the negative battery cable so the computer can reset and also just as a precautionary measure.  Then of course you need to take off your old MAF.  The next thing you will need to do is remove the sensor from each of the MAF bodies.  Sometimes they are held on with odd torx screws, if so just use pliers or find some other way to remove the screws.  Be careful not to damage the sensors as you do this.  Once you get the sensor off, it looks like this:

mafsensor.jpg (20522 bytes)

Now would be a good time to clean the two sensor wires if they are dirty.  You can use brake cleaner or something else that won't leave a residue, as the wires are very sensitive to deposits on them.  After you clean the sensor, take the NEW MAF BODY and attach the OLD MAF SENSOR to it.  [So you reuse your old sensor but put the new larger body on it.]  Now you can reinstall the assembled MAF into your car.  If you didn't disconnect the negative battery cable before, do it now and let it sit for at least 15 minutes with it disconnected.  This will let the computer reset and then it will re-learn everything with the new free flowing MAF on there.
That's about the extent of the MAF swap.   Reconnect your battery and start it up, hopefully it will run OK.  It would not surprise me if the car ran bad though because the MAF is a very sensitive part in making the engine run smooth (or run at all for that matter).
 
Copyright 2002 by Mike Mohr
Any posting or distribution of this guide without asking me first is not cool.  So don't do it.