Parallel install MS/factory ECM anyone?

[Exodus_2pt0]

Well I may go turbo on the E34. However I have a few requirements.

-No band aids, would be using my MS2 box setup to fire the coil. So spark/fuel control with megasquirt using the stock dizzy.

-The e34 must retain what makes it so great, comfort. This means working cruise control, gauges function, ect.

SO! I was reading about parallel installs. Removing the stock ECM's control over injectors/spark, but leaving it wired in to control the comfort features. Then splice in the MS to share tps/o2 signals and have the engine itself run off the megasquirt.

Anyone attempted this? Would I even lose anything by removing the factory ecm altogether?

I'm still reading up on the matter, but thought I would see if anyone has already done the hard work and could chime in.

[nando]

you don't need the stock DME for cruise control or functioning gages. CC is completely separate on these older cars.

just go with a PnP setup. most signals you can't splice..

[Exodus_2pt0]

Good to know.

Actually just finished adding the bip373 into the 3.57 this morning. Took apart a 55 pin dme I had laying around and going to make a PnP adapter whenever I get around to it.

[Cyrix2k]

What e34 do you have? M20/M30? Ding-dong-ditch the distributor and run wasted spark. As mentioned above, you don't need the DME for anything you want to keep although I haven't actually played with the cruise control yet. On newer BMWs, the MS can drive the tach circuit directly, but older BMWs (and I think all e34s are newer than this) require some simply additional circuitry. If you want to keep the econometer / OBC mileage working, visit seattle circuit and buy one of the boards to wire to the fuel injectors. If you're going turbo, it won't read correctly without the seattle circuit board or another solution anyway.

[Exodus_2pt0]

Very glad to hear I can keep the mpg meter! Less is more here, to the point that gauges will be in the glove box with a failsafe in case of over boost, ect.

That's a big negative on the wasted spark. Just going to run the dizzy with ms controlling the coil. Just finished adding the ignitor to the 3.57 board today actually.

My goal for this car is for anyone who drives it to get the feeling it came from the factory with 300whp. Nothing crazy, just a solid power output in an otherwise stock car. I'll even be fabbing the down pipe to mount to the stock cat back. Yes it will be restrictive but there's no reason I shouldn't be able to hit my goal with the hx35.

92 535i 5 speed BTW.

[Cyrix2k]

Very glad to hear I can keep the mpg meter! Less is more here, to the point that gauges will be in the glove box with a failsafe in case of over boost, ect.

That's a big negative on the wasted spark. Just going to run the dizzy with ms controlling the coil. Just finished adding the ignitor to the 3.57 board today actually.

My goal for this car is for anyone who drives it to get the feeling it came from the factory with 300whp. Nothing crazy, just a solid power output in an otherwise stock car. I'll even be fabbing the down pipe to mount to the stock cat back. Yes it will be restrictive but there's no reason I shouldn't be able to hit my goal with the hx35.

92 535i 5 speed BTW.

Why? Add two more coil drivers. The single largest improvement I saw in driveability came from wasted spark and it's even more important under boost. That, and if the M30 is like the M20, the cap & rotor cost more than the coil packs... You want a very stout ignition system for boost. Can it be done with the stock ignition? Yes. Can you run the same gap and hit the same power levels as with wasted spark? No. Will it be as reliable? (Arguably) No. The stock coil should be moved away from the turbo anyway due to the heat.

:edit: also look at this

http://www.r3vlimited.com/board/showthread.php?t=291812&highlight=boost+gauge

[Exodus_2pt0]

Thanks for the link to the boost gauge. Definitely up my alley for this thing.

I built my last MS box for wasted spark when I was planning to go all out on an M20. That car ended up with a 5.0/t5 drive train instead. Now fast forward to this car, my goals are much more daily driver oriented. The distributor should have zero problems pushing my power goal, which is why I don't feel the need to go WS.

Also, this is going to be PnP for the most part. That way if I ever have a problem with the MS, I can limp the car home using the factory ecm. Only going to be running 33lb injectors. Less is more here, shooting for a modest 300whp which is how I feel this car should have come from the factory.

[nando]

IMO for a DD wasted spark makes even more sense. All you have to do is add the 2 coil drivers and enable it in software.

seriously - it's more reliable and less expensive in the long run. I haven't had to touch my ignition in about 6 years (except for going from wasted spark to CNP). I think in the previous 5 years I spent $500 on stock ignition parts.

everything is cheaper - the plug wires, the coils, etc. I think my D585 coils *and* brand new wires cost less than a new stock M20 wire set. that doesn't count the $90 cap/rotor that crap themselves every 20k (at least if you want to keep your ignition in tip top shape). moving parts FTL.

I find it pretty unlikely that you would ever swap in the stock DME. it's possible, and I built mine that way originally too - but you'll never do it. these aren't the days of MS1 beta testing. :p