hi: i am a new member obviously. i just need a little guidance on where to start looking then i will shut up and search and learn from there with out bugging everyone with stupid questions. here is my deal: i am looking for info and suggestions on what ECU i should get for my "standalone". it is NOT for a GM though, it is for a 1991 BMW 325i. before you condemn me let me finish. it is presently running a split second piggyback that is less than spectacular and has no spark or timing control, just mixture. the current motor is a 2.7 stroker (in line 6) with a FORD MAF conversion, 310 deg cam, P & P head, and ITB's (6 individual throttle bodies) with a single TPS, long tubes,dual 2" exhaust with 2 2 1/4" magnaflow mufflers and no cat. i would like to get the system up and running/sorted out, before i swap in my 3.5 supercharged (M-90) M30B3.5 motor. sorry if this is all Greek to everyone, i just want to give as much info as possible to get the best advice. i am not a big fan of mega-squirt, and was looking at other standalone options, when my friend (who is also a head tech at a high performance corvette shop) suggested that i just run a GM ecu and adapt it harness wise. he offered me any ECU i want and what ever stock unmolested harness that goes with it along with any sensors i might need for free. that is a hard deal to pass up! his shop uses CATuners and one other programme that i can't remember off of the top of my head. this will give me unlimited help as far as the tuning end of it is concerned as well as unlimited access to the chassis dyno for tuning too. so here are my questions: since it is most likely going to be a corvette ECU, what would be my best choice for my application? ( i really don't have much knowledge about GMs or American cars to begin with, but i am a Porsche mechanic and have been working on high performance German cars or building race cars ((track)) for most of my life) are they all speed density? (i would like to eliminate the MAF all together if possible) is there any issues running a GM speed density with boost? (i am only going to run 15psi or less from the super charger as i am going to keep the car as a DD) the car is a manual tranny 5 speed so there is no issues with tranny control ETC, but i would like to keep the A/C i am assuming that there is idle control abilities for when the A/C is turned on? purge canister solenoid controls too? i really don't care if the ECU is OBD-I or OBD-II etc since, i think, it is irrelevant to my application. am i wrong in my assumptions? is there a more desirable ECU to have? that should give me some where to start searching for answers and go from there. i wont bother you with more inane newbie questions (hopefully) after this with out searching first. if there is any interest, i will post up the results and pic (even though it isn't GM powered) thank you in advance for your help/guidance, and sorry for the SUPER long first post Greg

one other thing, if it makes a difference. the ITB's are currently running 42lb injectors (6)

Hey der affe

It's Forced_Firebird from the e30 forums...

Anyways, guys be easy on him, even if it's not thirdgen related, he wants to use an ECM from us. I am doing the same swap in my 1986 BMW 325es, and here's what I got so far...

Using an external DIS wheel and a '727 ECM, I plan on using it to tune my bimmer. The injectors are the same impedance and the vehicle speed sensor (in the BMW) uses a magnetic pulse to relay for the speedometer, they also use a AFM instead of a MAF, but obviously der affe has already overcome that (it's a mechanical device rather than use a signal for air flow, cheesy, eh? :P) I'm hopng to use a DRAC and convert the BMW pulses to ours for the speed sensor, maybe we can be enlightened (of course after we finally pin down the pulses per mile haha)

I have the wiring diagrams if needed, but we are both inthe same boat as far as thinking outside the box.

der affe, cre to explain mor of your plans on the ITB's? How are you planning on running MAF with the TB's? Seems easier to me to use MAP with vac line running to a GM style MAP sensor and drop the MAF. Not only would it look better, but there are so many options for MAP tuning.

Idle air controol (IAC) is also another issue you are going to have to address. Glad to see you here...

I suggested der affe come here because this one of the ultimate OBD1 tuning boards IMO, and I'm not even partial

if your going to run boost. i think the code59.org board is something to check out.

its can be used with the 730 and i would guess your 727 along with the 749 that they made it for. the 749 would run low Z injectors with some mods.

there's already a turbo I6 280z running it. he posts here as well.

i think everything you want to do can be done with the info from this site. check the prom tuning guide book sticky at the top.

It's a 240Z. The 280Z was a later year.

Yes, code59 (www.code59.org) will work in the 7730/7749 (both under dash mounted) and the 7727 (under hood mounted). Code59 ($59) started life as $58, which was used in the Syclone, Typhoon and Turbo Sunbird. It has been modified by a great bunch of guys, to expand the VE table (3 BAR), WBO2 closed loop fueling control, and a few other features that I know I'm forgetting.

I'm going to suggest an OBD 1 ECM for this, since this is a bit more known and IMO at this point easier as a retrofit. There has also been plenty of code development for the OBD 1 ECMs, such as code59 and S_AUJP.

I know John (First/Forced_Firebird) will be using a '7727, so I have to assume that the OEM BMW ECM is under the hood and if it is, that would likely be the easiest ECM to use. There is a later service number that can be used in place of the '7727, but I don't recall the number.

Now there might be a bit of a glitch in ECM selection though, and that is whether your injectors are high or low impedance. The reason this is a concern is the '7727 and '7730 both have single injector drivers, while the '7749 has two. The '7727 and '7730 have been used on applications up to 8 cylinder using high impedance injectors without issue. I have read that with a change of the sense resistors and changing the injector sence wiring that a '7749 was used on a low impedance injector equipped 8 cylinder using only one of the two injector drivers, which was an oversight in the way the ECM was wired. So in theory a '7730 or possibly even a '7727 could be made to run low impdeance injectors, on a single injector driver in a 6 cylinder application with a sense resistor change and an external wiring change.

For ignition control there may be a couple options.
If the dizzy has a magnetic trigger, you can use a GM ignition Control Module from a few applications (2.8L in a S-10/Camaro as a couple examples), then connect the magnetic trigger to the ICM. The other connections would be just like any GM application, for control (ECM connections) and coil connections (ignition and trigger).

If you want DIS, the easiest way would be to grab an ICM and coil packs from a 60 degree V6 (FWD 2.8, 3.1, 3100, 3400, and RWD 3.4L), make a custom crank trigger (7x low res wheel), I did this retrofitting the DIS to an early 2.8L block, that didn't have provisions for DIS.

Speed Density and MAF are both options with the GM ECM.

Code59 is used with Speed Density, as well as S_AUJP. I don't recall what masks (code) use MAF off hand though. Since you want to run forced induction and eliminate the MAF, I would suggest using code59 to give the most flexibility.

Just as a quick primer:
The ECM is just the hardware, and can be used with many different "masks" or "codes". These "masks" are refered to by a hex designation (in most codes this will be byte 0x08). You may see examples such as $8D, $58, $59, $A1, $6E, $6D, etc. In many cases these codes (or more specifically the bins associated with those masks), can be swapped between different ECMs to get a combination to work best in your situation.

In my case, I am using a '7749, with $59. This is in a 1973 Datsun 240Z, that has an N/A 2.8L from an '81 or '82 280ZX, that I have added a turbocharger to. The engine in carburated N/A form came in the car when I bought it. I added the turbo and EFI over the past summer.

A friend of mine has a '1967 Chev truck with a 365 (smaller version of a 409), that he built an MPFI intake for (these engines were only ever carburated), and now have it running off a '7730 and S_AUJP, since he is N/A. FYI "S_AUJP" is really "$8D" code. The "AUJP" is the last release of that code from GM, and so that was the starting point for some of the guys here to modify and add to the code to give more flexibility and tunability to the user. the "S" in "S_AUJP" is short for "Super" or "Super_AUJP", differentiating this enhanced code from the basic GM release of "AUJP".

This will all seem like a foreign language at first and it is a steep learning curve but it will make sense in a short time.

weel i'll start off with the how i am running the MAF and ITB's.
pics first (sorry they are kind of big)









the split second (ARC-2A ) allows you to use the Ford T-bird (1996) MAF in place of the AFM (stock BMW) it does not, however retain the heating function that burns off the crud from the wires. so once a month i pull it and clean it with brake or electronic cleaner. i have heard of people some how making the later stock BMW MAF work with your stock ECU (miller performance for example). my ultimate goal is to get rid of the MAF all together. that would simplify things and work much better with my eventual boosted motor swap.

as for $ to gains ratio both these are low. on the plus side you get way better throttle response, they look cool as hell and sound really angry when you crack them open, because of the super short runner length you can run the cam zilla (310 deg) that i am with out problems caused by valve overlap and intake pulses confusing the computer. they do make more HP than the stock intake, but since when you start to twist them over 7K they tend to break rocker arms, it is a bit of a waste. a big downside is the price. last time i checked it was around $3800.00 for the Dbilas ITB's (shipping was additional and they come from Germany) and the MAF conversion was around $550 that includes the piggyback (ARC-2A). i bought the car with a super eta 2.7 stroker and everything already on the engine for $4500. i think i did pretty good. i am ready for something a lot more fun though after 3 years.

i really like N/A motors though, so my options were build an even better stroker, do more head work, and rebuild it ($$$) and still not be much over 200WHP....ORRRRR M30B3.5 with an M-90. that will only add around 50-70lbs more to the car and put me at around 370WHP and 390FTLBS of torque. the ITB's have sealed O-ringed throttle shafts so i will be blowing through them. the short intake length also will make plumbing them way easier too. the S/C motor should drive more like an N/A motor too, especially with the addition of the air to water intercooler. i also have a wet NOS kit laying around that i MAY either spray on to the heat exchanger for the intercooler liquid, or if i am feeling like living on the edge spray into the motor (6 foggers is a lot of plumbing though). i would have gone turbo, but (and being from FLA you can relate) the summer temps here can be brutal. i have seen problems with turbo cars cooking the wiring harnesses insulation and breaking because of the under hood temps.

ok enough boring the non BMW people here.

on a side note though, my roommate and i are looking for a cheap E-30 to do a 6.0LT LS swap/6 speed swap also. as long as the rear end will hold up that should be a stupid fun car! once that gets rolling i will share pics too.

thanks for the info. that is a lot to digest! i may have to ask my friend and my roommate to help decode what is what in the post, but from what have gathered so far...........

if i run boost i will need an ECU from a vehicle that was originally boosted correct? is there not enough parameters/resolution to run a N/A and boost on the same ECU? (if i missed that explanation please forgive me, i am new to this).

should i look for a V-6 ECU because the basic fuel and timing map already exist there and it will be easier to modify for my application. remember that i am going to get it up, running and sorted out with an N/A application first. then once i understand it and have it sorted. i will begin the swap and retune it the newer, bigger, boosted motor.

it looks like the injectors are the same impedance/voltage as GM according to forced fire bird. it uses a front crank trigger (magnetic). the speed density is a go for sure.

once my roommate gets home i am going to show him the posts (he is a BIG GM guy) and have him break it down before i ask anymore questions. that way i have an idea what i am talking about.

No, the ECM itself does not need to be originally from a force fed application.

GM even used the same ECM in force fed and N/A applications. As an example the '7749 was used in both force fed and N/A applications. The '7730 was used in N/A application but by using force fed code ($8F, $58, $59, $60), force fed engines have been ran from these ECMs, that were originally used in N/A applications.

The code (bins) can be downloaded and programmed to an EEPROM or sent to an emulator to essentially change the function of the ECM.

The ECM itself also doesn't know what engine it is or was attached to. The only thing hardware wise that you will need to try and match up as closely as you can is the MEMCAL. The MEMCAL has an EPROM that has the bin stored on it, but more importantly there is the limp home mode resistor packs and knock sensor filter in the MEMCAL that should be matched at least by cylinder count to what you are using. Luckily the 6 cyl MEMCALs are easy to come by. I actually have several sitting in my ECM hardware pile.

Greg (der affe),

(also a reply to your PM)

I have an external DIS wheel that is used on the FWD 60 degree V6 conversions. They were made so that a late model engine can be put in an earlier car. If I can't get the BMW reluctor configuration to work, I will use it as a back-up plan...

http://wot-tech.com/shop/all/externa...r/prod_42.html


Six, the BMW ECU is in the glovebox, but I just happened to pick up the '727 for $20, so that's what I will be using (if the BMW happens before another project I have going on ).

Anybody who wants to look over the BMW wiring diagram in hopes that it may help (page 27 or so)...

http://www.armchair.mb.ca/~dave/BMW/e30/


It appears to me that the BMW (Motronic ECU in my case, circa 1986) only controls the engine functions, and doesn't appear that it has control over as many functions as the GM OBDI. This may be a good thing since all I really want is control over fuel and ignition timing.