trying something really weird with a I6 ECM
im trying something really different, and im pretty sure no one has done this. well, at least no one has been dumb enough to waste their time and try this. if it needs to be moved or whatever, sorry, i thought this was the best place to put it.
im turboing my BMW M3. for those not in the know, its a 3.2 liter inline 6, with (on/off, not infinatley adjustable) variable valve timing (vanos is what its called on BMW's). s52 engine
im having a difficult time getting the stock ECM (BMW calls it a DME) programmed, or "cracked" in order to tune it. there are only a few tuners that will do it, Active Autowerks, and a few others. AA is the only company that will remote tune, and its 1000 bucks to start. that still doesnt allow you tune later if your gonna change something on the car. you still have to soley rely on them to tune your stuff. if it aint right, you have to send it back, get it flashed, get it back, go back to dyno and check....etc.etc. everyone else wants you to trailer your car to them (in my case half across the country) to tune at their place, on their dyno. suck.
so then i was going to go stand alone, but then the OBD II part dissapears, and then its a bitch to get it passed for inspection (OBD readiness codes). suck. its also $$$$$$ ( 3000 bucks is the norm im seeing for a sequential injection, sequential ignition with tunability for boost and other stuff)
then, as i was watching a well known tuner from the board here tune a LS1, i got this stupid ass idea. after seeing all of the variables that can be turned off, on and modified, why not put a ECM from a chevy onto my BMW? chevy makes a inline 6 cylinder in the trailblazer, and its tunable by a few aftermarket tune companies (like HP tuners) and hell, theres a ton of shit you can tune thru those guys.
so i got busy trying to do my homework.
i have looked over the BMW schematics, and the chevy ones, and i think my major problem will be crank and cam sensors. both of them run hall effect sensors, but the amount of teeth is whats fawking me up.
1) problem with the crank:
the BMW crank sensor has 58 teeth, with two teeth missing. its on the back side of the crankshaft, inside the engine. have to pull the crank to get to it. suck.
the trailblazer crank sensor is 7 machined slots, of which are equally spaced 60 degrees apart. the 7th slot is spaced 10 degrees after one of the 60 degree slots. so it makes 7 pulses every crank rotation, and the 10 degree pulse is known as the sync pulse. i dont know where it is on the engine (on the crank, duh) or what it looks like.
2) problem with the cam sensor:
the BMW cam sensor is a peice of sheetmetal, essentialy. its sending a signal every 1/2 rotation of the INTAKE cam. so it looks like half a circle of sheet metal on the front of the cam.
the trailblazer cam sensor sends 6 pulses every rotation of the EXHAUST side. each notch of the reluctor wheel is a different size, for individual cylinder identification.
from what i understand, it then uses the crank and cam sensor to figgure out where the variable cam stuff is in relation to the crank. so i think it is using them in series to fire correctly. if the cam sensor goes away, then the car doesnt run correctly. how am i going to show it on the intake cam sensor, not on the exhaust cam? im sure the phase of the cam sensor is going to be different to the ECM if moving from intake to exhaust.... unless i can take the "correct" position of the exhaust cam in relation to it on the sensor, and just transfer it over the the intake cam w/o moving the engine.
BMW, from what i see, is looking at the intake cam, and the crank when firing off, but then uses the crank sensor as the main way of running, and uses the cam sensor to figgure out where the cam is on its variable stuff.
so. it would be super awesome to just be able to tell the trailblazer ECM, this is what the crank and cam sensor now is, so use it. im hopeing its like this, but doubt it will be that easy. problem is, is i dont know what the crank and cam sensors on the chevy look like. im sure diameter, thickness, and size will be critical to get it to see the signal correctly.
on the cam sensor, there is no provision to put a sensor on the exhaust cam, but the intake cam sensor ring could be made out of something billet machined, and installed where the original cam sensor sheetmetal ring is now. i dont think that would be *too*hard.
crank sensor on the other hand, i dunno what to do. can i just tell the chevy ECM, use this 58 tooth ring to run? i know you can use the wheel speed sensor from ABS to show a tailshaft speed, when pulling the 4L60E out for a turbo 400...... so something like that be done for the crank signal?
another thing i was looking at:
the throttle. apparently, the trailblazer is a drive by wire?
i think my pedal position sensor on my car would work, since both cars use a 5 volt reference, one going up and one going down for redundancy.
so i might be using a trailblazer throttle on the car, so the ECM can idle and fucntion without failsafe. reason i say that, is the BMW uses a idle valve to control idle, and is mechanically throttle dependant.
if you can answer any or comment on what im thinking on doing, please, i would appreciate your guys experiance with these LS1 type tuners and their capabilities.
can i turn off the fuel tank pressure sensor? can you change this variable?
does anyone know the pressures the A/C pressure sensor trips at? can you change this variable?
does anyone know if the intake temp sensor is in the intake manifold? is it a PTC sensor? can you change this variable?
same thing with the coolant temp sensor, is it a PTC sensor? the hotter it gets, the more resistance it makes? can you change this variable?
if i get a trailblazer ECM, can i make it a manual transmission, if it came out of a automatic transmission car?
does it need to see wheel speed? im sure it does.
can i turn off AIR, and EVAP controls?
does it have to use the ABS signals to work correctly?
what signal is the RPM signal?
what about speed signal for the speedo?
oil pressure, water temp signals?
other than that, the similarities are very close.
it has a MAP sensor (bonus!) meaning no MAF like i have now. will this map lock out under boost? will i need a MAP clamp, and an aftermarket MAP sensor to see boost?
it controls the fuel pump, like my DME does.
it controls the A/C compressor, like mine does, including looking at the pressure sensors.
power and ground connections look easy enough, for constant power, and key on and start.
MIL light looks the same for hook up.
O2 sensors are 4 wire like mine, and seem to be able to hook up easily.
injection and coils are the same (about)
fuel pump relay is controlled by ECM, like mine.
anyways, this is a huge undetaking right now to see if it works. i need a GM 4200 series ECM and the connectors for it, including a foot or so of the wiring, so i can try to make it a plug and play on the BMW engine harness. the way i was going to do this, is hack up a BMW DME to i can use the male side of the connector to hook up to the engine harness, while wiring in the GM ECM into the back of the DME connector.
any help would be appreciated, and if you have this for sale or comments, feel free to PM me or post up your thoughts
