m42 / m44 interchangeability

[wodcutr]

I just bought a 98 318ti without a motor and was wondering if anyone could tell me if an m42 would be a usable motor in place of the m44 or should I just source a good m44 because it is not worth the hassle to convert.  Thanks!

[DesktopDave]

Go with an M44.  There are significant differences between the electrical systems.  For instance, none of the M42's have a MAF (all are the flap-type AFM), among other differences.

If you really wanted to get the best of both worlds I'd use parts from  both.  I strongly suspect it can be made to work, but I'd go for the M44 if you're looking  for plug-n-play.

You could use an earlier M42 if you swapped out the entire harness as well, but that raises legal problems...our mechanics in PA would cite the missing OBDII as a safety & emissions inspection fail.  Our DOT isn't even that strict, can't imagine what it'd be like in CA...

[rsdvr6]

I ran across a fresh M44 yesterday at my local pull n save, was thinking about a pulley swap for my '91 M42 but the alternator seems like it may pose a challenge. I would do the M44 unless you ditch it all and do a "big" six swap. Let's hear it for an S52 318ti!

[wodcutr]

I thought about throwing a 6 cylinder in there, but the car is for my daughter and I doubt she would appreciate a swapped ti!