Debate: OBDI vs OBDII -Management- who is better!!!

[btec116]

Hey guys, this is my first thread (Noobie), I'm just learning to walk...

There seems a great unspoken law for everyone to go OBD-I management and junk the OBD-II for any M/S52 swaps.

I dont understand the logic behind this choice, and dont beleive its the right one.

I am about to put an M52B25 from a '97 323i into a 89 318i. I see the OBD-II (that is Siemens MS41-series DME's) as a superior choice over the OBD-I (Bosch Motronic) system, as far as engine management goes.

To define this a little better, I am concerned strictly with the the way the two systems actually manage air/fuel and spark, and how these affect the characteristics of the motor; that is power and torque, their peak values as well as spread, and response. Lets not get into emissions and consumption, I dont think its a factor any of us regarded much when we decided to embark on this project.

My argument is:
People that use an M/S52 and convert to OBD-I electronics are taking a step backwards (I can see you all cringe)

The ONLY justification for this that I have come across on this forum are:
1. For the freeer flowing inlet manifold, which is not an electronic component,
2. The dreaded EWS, which everyone fears (yes I have to deal with it too).
3. Everyone's done the wiring on mating E30=/=M50, and its easier.
In my mind these are not enough to warrant getting rid of a better management system, so there must (hopefully) be alot I dont know.

Now before I back up my bold statement with -anything- factual, I want to hear your opinions (if anyone cares). I'm a baby, here to learn, so Im all ears!

Thanks in advance to anyone who replies!

[PiercedE30]

The hardest part about using OBD-II electronics is getting a proper tune and finding someone that can do it for you.
Honestly, I do believe that the OBD-II computer is vastly superior to the OBD-I computer.

Jon

[aeryk7]

Yep thats why it utilizes 4 oxy sensors rather than one. It is a much more advanced system but will cost more money to run in the long run then an OBD1 system . With a more advanced sytem you will also have the ability to throw more codes that could be a good thing or a bad thing. Emissions codes will annoy you though especially if you were driving a real obd2 car with emissions.

[matt]

Yep thats why it utilizes 4 oxy sensors rather than one. It is a much more advanced system but will cost more money to run in the long run then an OBD1 system . With a more advanced sytem you will also have the ability to throw more codes that could be a good thing or a bad thing. Emissions codes will annoy you though especially if you were driving a real obd2 car with emissions.

It uses 4 oxygen sensors because it is required (by the EPA) to measure catalyst efficiency. They would much rather have used two.

The hardest part about using OBD-II electronics is getting a proper tune and finding someone that can do it for you.
Honestly, I do believe that the OBD-II computer is vastly superior to the OBD-I computer.

Jon

It's not a matter of belief... the Siemens box is way way way better/faster/more powerful than the Motronic, just like the motronic is much more powerful than previous Jetronic boxes or whatever else.

Progress is a one-way street... even if it doesn't always seem like it (to look at the HP numbers between the M52B28 and the M50TUB25)

[aeryk7]

It uses 4 oxygen sensors because it is required (by the EPA) to measure catalyst efficiency. They would much rather have used two.

This true and creates a bigger threshold of codes example catalyst effieciency codes. So if you dont want unnecessary codes dummy O2 sensors come into play and you spend even more money

[matt]

This true and creates a bigger threshold of codes example catalyst effieciency codes. So if you dont want unnecessary codes dummy O2 sensors come into play and you spend even more money

It is possible to "turn off" the rear O2 sensors in the software so no dummy sensors are needed.

The bottom line is that for now, it's much easier for most of us to just OBDI swap our motors, but at some point, it will be possible to program the OBDII computer easily so that we can start using them more or less as standalones.

[PiercedE30]

Can you "turn off" the EWS on the Siemens box?

[matt]

Yes, of course.

[Jason89i]

Yes, of course.

please tell. i was aware of one person in germany that opened up the siemens box, soldered on some wires and was able to delete ews2 on a m54b30. have you done this???? it would be nice to know for my next project.

ews is not hard to wire. obd2 has a MUCH faster processor that can do a lot more.....but as stated earlier......tuning is not as easy. most conversion guys like to do things cheaply. an obd1 chip is 50-300 for tuning and comes in LOTS of flavors. there is no "chip" for the obd2 cars and would require expensive tuning.

cheers, jason

[vr4boy]

Can you "turn off" the EWS on the Siemens box?

apparently yes,when i installed an AA s/c on my 96m,the prev. owner sent his ecu w/ the AA software to bimmerworld and had the ews deleted-it was a plug and play install on my car i didn't have to align the ecu to my car....

[btec116]

Thanks for the replies guys!

Progress is a one-way street... even if it doesn't always seem like it (to look at the HP numbers between the M52B28 and the M50TUB25)

Matt I agree wholeheartedly. Take M50B25-M52B25; every component has been redesigned to be smaller, lighter and perform better in the M52. Its evolutionary. As far as numbers (for the 2.5's) peak power is 20HP less at 400RPM lower, while torque is the same, 250RPM lower. These numbers are not an accident, they have been well-thought out. The M52 is an awesome base (and around here you give an arm and a leg to get S motors). Changing inlet manifold and cams is something thats possible to do progressively (for those of us on a budget) while running our DD. As for the DME mods...

Does anyone tune the Siemens? Is it just expensive, or not possible?

and creates a bigger threshold of codes example catalyst effieciency codes. So if you dont want unnecessary codes dummy O2 sensors come into play and you spend even more money

As far as fault codes go, you shouldn't get any that that trigger a limp mode, or??? Only one I know of is the DME needs a digital speed input, or it will limit redline to 5500. But this only affects revs, and mine's making peak power by then anyway:)
As for all the rest (body codes, etc) who cares? Like others have done, read the codes periodically, make sure there are none engine related, go drive.

It is possible to "turn off" the rear O2 sensors in the software so no dummy sensors are needed.

I didn't know about this. Could you please expand on this?
I have been scratching my head about the "other" lambda sensors for a while now; I thought mine had three; one for 1 cat on the single 323i system, but only saw this off parts diagrams. I dont have the original exhaust, and never found the plug for the third lambda sensor on the engine harness...
Then I was at a workshop that had an E39 528i up on a hoist. To my surprise, it had NO sensors anywhere downstream of the headers. Either I'm really going blind, or could it be possible these are omitted in some markets? THings are pretty relaxed in AUS for emissions... Anyway, I need to look into this.

[matt]

please tell. i was aware of one person in germany that opened up the siemens box, soldered on some wires and was able to delete ews2 on a m54b30. have you done this???? it would be nice to know for my next project.

ews is not hard to wire. obd2 has a MUCH faster processor that can do a lot more.....but as stated earlier......tuning is not as easy. most conversion guys like to do things cheaply. an obd1 chip is 50-300 for tuning and comes in LOTS of flavors. there is no "chip" for the obd2 cars and would require expensive tuning.

cheers, jason

Heh... I didn't mean I can, I mean it's possible. The guys who do OBDII tuning should be able to handle it... AA, Nick G, Jim Conforti/Turner, probably Bimmerworld.

[PiercedE30]

Anyone know the average cost of OBD-II tuning plus EWS/Second O2 sensors delete? Just so people will know what it would cost.