using m44 maf based efi on m42

[Ramblin MAn]

I'm in a uniquie postion because my M42 is a transplant into an 82 e21 320i.

I'm wondering if I couldn't just swap out the wiring harness and computer and go with the harness and injection from a later e36 m44 thats already designed to use a MAF.

I've actually thought about going backwards using the setup from a first generation SAAB 900 turbo.

Basically my question is are there any cars out there that I could just grab the fuel injection electronics and wiring from and just plug it in and go?

[bmwman91]

The simple answer...no.

The negativity, explained:
It would be tough, and absolutely not a plug-n-play swap.  The M44 has a couple of similarities to the E36 M42 that the E30 M42 does not...knock sensors and the fancy schmancy DISA intake manifold.  The valvetrain is vastly different though, and probably has different fuel & spark maps due to the likely different flow patterns.

The M44 was an OBDII motor however, and all M42's are OBDI.  Unless you go stand-alone, the cost involved in the OBDI swap would be horrendous, and would probably include custom chip tuning anyway ($$$).

Some hope:
Now, all hope is not lost.  Before worrying about anything more, get the engine transplanted and working 100%.  Some companies sell MAF converter kits, though they are pricey and require dyno time (even pricier).  I am in the final stages of development on the 3rd generation of a MAF converter that is plug & play at a target price of about $250 (w/o sensor...those are usually $60-100 depending).  Once I am satisfied that ALL kinks are out, I will feel right about selling some.  I have been promising this thing for a long time here...I am going to get lynched if it is not done soon!!!

Anyway, keep us posted on the swap progress.  The M42 in an E21 will sure liven it up a tad!

[D. Clay]

I have been promising this thing for a long time here...I am going to get lynched if it is not done soon!!!

Don't feel like the Lone Ranger! I had a 1971 240Z Datsun that I was restoring. I had it stripped to the tub and finally sold it as an IT car (it was worth more that way) It sat for so long - 3 years - that my wife began calling it "the alleged Z-Car".

[tim_s]

bmwman, im not sure i quite understand your post. why would you want to obd1 swap if you changed to m44 injection?

I also don't think a project such as this is as much of a lost cause as you make out. OK so it would be a fairly substantial project, but I have quite a bit of experience with the later cars, and reckon it would make an interesting project; if anyone's serious i could help along, you'd need some ETMs, to be handy with a soldering iron, carsoft, lead, the EWS trans/receive etc. as well as mor parts from the donor car than you'd imagine.
As far as sparks timing is concerned, the m44 sparks map is very good and would be pretty good on an m42 i reckon; i have a copy of both maps. its certainly an interesting idea and as long as you're prepared to be a bit of a guinea pig, i reckon its a pretty good idea. I really like M5.2, and think the m44 is really well-mapped. it could potentially make for a really sweet running m42.

[bmwman91]

The reason for the OBDI swap is that...swapping the M44 motor controls to be OBDI is a lot cheaper & easier than making an OBDII E21.  OBDII has everything from multiple O2 sensors to deal with, to traction controls, even gas filler cap seal sensors.  LOTS of work.

[tim_s]

The reason for the OBDI swap is that...swapping the M44 motor controls to be OBDI is a lot cheaper & easier than making an OBDII E21.  OBDII has everything from multiple O2 sensors to deal with, to traction controls, even gas filler cap seal sensors.  LOTS of work.

(on a uk car at least) this is incorrect: Single 4 wire O2 sensor, ASC just uses VSS sensors but is not required, no gas filler cap seal sensor. I still don't think I understand what you mean by swapping to OBD1 - what exactly do you mean? i think i'm missing something, might be a UK vs US thing.

To be honest, I don't even understand why you'd want to, fitting a few sensors is not really a lot of work (especially from the man who's spent months developing a MAF controller for motronic 1.7!)

[bmwman91]

Well damn, folks overseas must get a real break.  OBDII in the US was mainly for smog purposes, and added a crap load of sensory equipment to the car.  Folks who want to toss M/S52's into their E30's have the same problem...either drop like $6k on an OBDI conversion kit, spend maybe a couple thousand sourcing parts themselves and doing all necessary mods for an OBDII chassis conversion, or go the cheapest way and do stand-alone.  My bias on the M44 swap being hard is based prettymuch upon other enthusiasts' accounts of the OBDII 6-cyl swaps.

[Ramblin MAn]

Well I've seen that there are several "programming" pins on the ECUs that turn speciffic funtionality on or off like the O2 sensor.

Aside from all of that though. Right now I'm waiting until the afternoon to paint up my new to me stock intake manifold and throttle body. I'm going to mount up the stock setup and see if all of my problems go away.

The original owner was doing this group 5 racer thing with the car and the manifold was supposed to be turbo'd. So, it's no wonder the thing doesn't run right.

Personally I think I could put an L-Jetronic ECU and harness from a 85-86 SAAB 900 turbo on this thing and go.  The only thing I'd need to change is the TPS. I wouldn't even need to put the APC over because all that really is is a stand alone knock sensor and boost controller. With no turbo (yet) I don't need it.

I have a 85 900 turbo as my daily driver. Rescued it from a field, completely went through the car and it took me a while but it runs like new or better, and before I starten fooling with Motronic, I thought it was complex. I gues I cant use the l-Jetronic from an 85  because of the crank triggered ignition but the later 900 turbos would translate pretty well.

I guess all I'm saying is we have 1.8 liters to play with. Surely BMW, SAAB Volvo, VW or Audi has got an ecu and a harness I can grab from the junk yard and get the m42 to run nice without that damn flap getting in the way or the need to get megasquirt or a PCIII.

Remember this is essentially a hot rod. So think 32 Ford Roadster or kit car or something.