m42 to m20 swap

[Vonman]

Hey guys my 91 318i's m42 is not doing so well and I can't figure out what the hell is going on with it. We(mechanic friend, my dad, and me) aren't sure if it's the engine or if it is a sensor somewhere. I think that the head is cracked but that is just me. My dad says it might be the O2 sensor and my mechanic it is the coil packs.

So I have been looking around and have found a complete m20(engine, tranny, cpu etc) set up out of a 89 ix with 170K on it for dirt cheep and I am wondering how hard is the swap? Will it be a basic plug and play, as in pull the m42 drop the m20 in and change the cpu or is going to be more like a m50 swap where I need to replace basically everything.

Also would it just be better to have the m42 rebuilt or buy another m42?

Anyways if someone could shine some light on this that would be awesome.

[Borsig24]

IX block is different I think

[slow e30]

you are aware the IX is AWD and the m42 is not? you want a 325 car to donate the m20. gl

[Asbradley21]

Won't work. IX's are different.

[tjts1]

Have you checked for vacuum leaks in the hoses below the intake manifold?

[slow e30]

or the CPS? the crank, not cam.


and no, not child protection service either.

[Vonman]

I do know that the IX AWD, I just don't see how the blocks would be different. Wouldn't it be the transmission that is different? because the transfer case is at the rear of the transmission. Also I was going to pick up the whole set up T-Case and all, to do a AWD convert but the guy never got back to me.


I have indeed checked for vacuum leaks and have found none. I have put many man hours in to her, with no significant results as of yet but checking the CPS didn't even occur to me, how would I go about this?

If anyone would like to know exactly what is going on I will post the symptoms.

Thanks guys

[wolfgangstbd]

that would be ALOT of work to convert to awd

[Vonman]

that would be ALOT of work to convert to awd

Indeed, I looked in to it more and it would have been A LOT of work. I wouldn't have had the time to do it, if I did get in to it someone would have picked up a unfinished RWD to AWD convert for super cheep


Anyways thanks for the input guys.

[strad]

Reading the original post, it sounds like there's a whole lot of guessing going on. The proper thing to do is to test each suspect component to see if it is doing what it is supposed to. Eliminate the possibilities one by one and you should come up with the answer eventually.

Swapping in another motor is not the answer at this point in time. It might be the answer after you know, for sure, what is causing your symptoms. Unless you just don't like M42s. In which case, why go to as much bother trying to figure it as you already have? Buy an M50 and swap that in. Don't bother with an M20.

[Cobra Jet]

Dude - get in your vehicle, stick the key in the ignition, turn it to "on" WITHOUT starting it and pump the gas pedal 5x evenly and consecutively. The CEL will then start flashing, count the flashes and those will be your error codes. Error codes are (4) digit codes.

You can't be sitting there "guessing this or that" or have others doing the same, otherwise you're throwing money out the door by throwing parts at the vehicle...

Can you explain any of the assumptions above for - Head gasket? coils? O2 sensor? You're merely guessing and not trying to diagnose properly.

What's the exact problem - is the car starting, not starting, runnig but stalling, running but idling weird, etc etc etc....????? DIAGNOSIS IS KEY.

You need to extract any stored error codes and then go from there.

I will tell you this - for whatever reason, the M42 will NOT store ANY error code for a failed, failing or non-funcational CPS (Crank positioning sensor). There have been many reported failures of this part and for every single thread out there on multiple BMW forums, all of those who have experienced a failed or dead CPS (including myself) have never been able to extract an error code for such, nor does the DME store one even though the code does exist. A failed or failing CPS will be:

1) car will have sporadic starting issues
2) car will idle sporadically when coming to a stop or while driving - or may attempt to or will stall
3) car will not ever start once a CPS is 100% DEAD
4) no error code will be stored in the DME for a dead CPS

You HAVE to read through this thread for all diagnosis and test procedures available when trying to diagnose for a non-start:

http://www.m42club.com/forums/showthread.php?t=5462

You should post up what your vehicle's issues are, this way you can get better help... Swapping in an engine is not the answer - suppose your engine swap does not go well and you can't figure out why that is now not working - you're still stuck... then what, go swap another motor?

[zav3n]

WTF why m42 - m20.... m50 ftw its gunna be much easier than a m20 and the m20 wont pass smog anyway.... and the ix oil pan has a fucking axle going thought it....