OBD2 to OBD1 Conversion (A Learn-Me Thread)

I'm building a 1998 BMW 323iS for the GRM $200X Challenge, but I want to be able to sell the car after I've flogged it in Gainesville in October. Here in Massachusetts, there's a rolling 15-year emissions exemption, so the CEL doesn't matter, but I don't want to limit my potential buyers to MA customers when the time comes. All that said, the problem is that my 323 was converted from automatic to manual and has a CEL because the ECU can't communicate with the (now missing) automatic. I tried a manual ECU and it kills the spark. Apparently, I need the EWS, ignition lock cylinder and the key from the car that gave up the ECU ($500) or $1000 of custom ECU programming to make it right. Obviously, none of that will make the car faster at the Challenge and it might blow the budget entirely (I'm $1460 in right now, but I haven't sold any surplus parts yet). I still have the 1993 325iS parts car that gave up its transmission, and I wonder what's involved in simply converting the 1998 car to use the 1993 (OBD1) electronics. As a bonus, I'd get to upgrade the 323 to the big-runner M50 manifold for more power (which will help me at the Challenge). Is it as simple as swapping engine harnesses and ECUs? I'm scared to tear into it because, at this point, at least the 98 runs, even with the CEL.

https://grassrootsmotorsports.com/forum/grm/bmw-e36-m50-for-z3-m52b28/92655/page1/

Depending on who you talk to, it will be an easy swap.

Have you considered pulling the bulb and/or wire out of the CEL?

It doesn't sound like you care, or have any need for a working CEL.

I see no point in installing the EWS, unless you are trying to potentially make a lot of other chipped components non-functional.

In reply to SVreX:

What other bag of snakes would I be opening by swapping the EWS? What other chipped components are there?

In the Z3 thread, someone said it's "easy to eliminate EWS now". If anyone knows how to eliminate it, keeping the car OBD2 & just getting rid of EWS would be my first choice. Thanks!

In reply to SVreX:

Not sure about MA, but here in TN they're wise to the "pull the bulb from the CEL" trick. If it doesn't come on when you turn the key to accessory it's an automatic emissions test failure.

In reply to Will:

That's how it works here, too

In reply to M030:

If you're concerned about keeping the car emissions legal for sellability reasons, then don't bother removing the OBD-II controls. That'd be a fail here.

Well, they'd get a lack of communication, so they would run it on the rollers, and it would fail THEN, because BMWs suck at passing roller tests. The cats are way back by the rear axle and they cool off when you're idling in line for 20 minutes.

You can use the manual ECU with a flash to remove the EWS. Call Bimmerworld or Turner.

Actually I think the CEL light will matter in MA. Even though you don't test the car for emissions via the obd2 port once it is more than 15 years old if the light comes on and stays on I think it is a fail.

I will have to verify that. I just got my MA state inspection licence and I seem to remember that having that light on would cause it to fail the dash light part of the inspection.

Will wrote: In reply to SVreX: Not sure about MA, but here in TN they're wise to the "pull the bulb from the CEL" trick. If it doesn't come on when you turn the key to accessory it's an automatic emissions test failure.

Same in MA.

In reply to Giant Purple Snorklewacker:

Sold! Who can do that for $400?

Is automatic transmission really a downside? I mean, at the drgastrip it might hurt but you're not going to ge doing very well there anyway. At the autocross it should be a big benefit since you won't ever find yourself out of 1st gear or too slow for 2nd, since BMWs have crappy manual trans gearing and automatics usually have relatively tall 1sts because the torque converter adds multiplication from a stop.

M030 wrote: In reply to Giant Purple Snorklewacker: Sold! Who can do that for $400?

Anyone who does custom tunes for BMW OBD-II cars. Bimmerworld, Turner, Epic ... etc. They will either need the ECU or send you a "shark injector" type doohickey. Call and tell them what you want - you can also get a nice tune for larger injectors, cams, headers, etc... higher rev limit, etc. while you are at it.

In reply to Giant Purple Snorklewacker:

Thank you!!!