DIY: In depth M52/S52 OBD2 swap

[craiggroves91]

Another question. For those running the M50 intake manifold. What throttle body do you pair with it? OBDI or OBDII? Or does it matter and why?

Thanks again.

That depends mainly on what conversion kit you get I believe. The kit I got from m50manifold.com comes with new custom throttle body gasket that allows you to use the OBD2 TB on the M50 manifold.
I believe it is also fairly easy to run the obd1 TB.

There is TONS and TONS of info about m50 manifold conversions. Quick google search will give you any answer you need

[maniacmatt]

Another question. For those running the M50 intake manifold. What throttle body do you pair with it? OBDI or OBDII? Or does it matter and why?

Thanks again.

[craiggroves91]

I mean the universal OBDII connector usually found under the dash on OBDII cars. Like this.



How and where are you guys wiring and mounting it?

I thought thats what you might be asking. Well I didn't have it wired it, but I'm sure its possible and not crazy hard. It's more simple to just used the one in the engine bay though

[maniacmatt]

What exactly are you asking?
How to mount it?

I mean the universal OBDII connector usually found under the dash on OBDII cars. Like this.



How and where are you guys wiring and mounting it?

[craiggroves91]

This is a great write up! Awesome info!

What do all you OBDII guys do for the diagnostic port?

What exactly are you asking?
How to mount it?

I bought something similar to this, works fine and real cheap.
http://www.ebay.com/itm/BMW-20pin-Co...d37cbc&vxp=mtr

I might need to get one of those!

[Slovik]

I bought something similar to this, works fine and real cheap.

http://www.ebay.com/itm/BMW-20pin-Connector-to-OBD2-OBDII-16-Pin-Connector-Converter-/140892142780?pt=Motors_Automotive_Tools&hash=item20cdd37cbc&vxp=mtr

[maniacmatt]

This is a great write up! Awesome info!

What do all you OBDII guys do for the diagnostic port?

[PeabnutBubber]

On my original post I already thanked you but I figured I would do it here as well. HUGE thanks for this, man. As soon as I'm ready to start this project this is going to be a massive help. It seems that pretty much everything is in here. All I need now is some parts and a little bit of time. Thanks again! I'll update the other thread as I do it in case anyone's interested. Stop by Tallahassee for a beer one day!

[craiggroves91]

Added electric fan and reverse lights information

[craiggroves91]

Also: Best way to do OBD2 IAT sensor is thread it into the OBD1 sensor port ;)

I'm not sure if this is really the BEST way is it? What makes it better than the boot?

I realize you deleted the throttle circuit so you needed the sensor to plug that port, but it screws directly into the port to it's left with no modifications,that's just a plug for the extra hole on the OBD1 heads used on early OBD2 engines. Not all OBD2 motors have that, but what I did on my 99 S52 was get an OBD1 head and have it machined to S52 spec and gain the extra sender hole.

Wait, so you're saying on my s52 head that plug has the same threads as the unmodified e30 coolant temp sensor?

interesting

If you say the original spot for the IAT sensor is on the intake manifold, and your putting it in a hole in the intake boot, what use to be in that hole in the intake boot originally?

Well since its a boot from an OBD1 car its different and that hole is not needed on OBD2 car.

I'm not sure what that hole is used for on OBD1 cars, I'd have to look at one.

[VinniE30]

Intake boot and IAT sensor:
You'll want the long OBD1 intake boot with 2 holes in the bottom. One for the ICV hose and the other to either plug or mount your OBD2 IAT sensor in.
I chose to mount my IAT sensor in the boot, since this is more ideal than rethreading it to mount it in the original OBD1 IAT spot on the intake manifold.
To mount the IAT sensor in the hole you'll want to shave off some of the plastic to make it more round like pictured below.
Before:

After:


OBD1 intake boot part number: 13541738757

If you say the original spot for the IAT sensor is on the intake manifold, and your putting it in a hole in the intake boot, what use to be in that hole in the intake boot originally?

[giantkeeper]

Also: Best way to do OBD2 IAT sensor is thread it into the OBD1 sensor port ;)

This is what we did on tttoon's car. Easy to do and worth the extra 10 minutes!

[Mr.SWISS]

I realize you deleted the throttle circuit so you needed the sensor to plug that port, but it screws directly into the port to it's left with no modifications,that's just a plug for the extra hole on the OBD1 heads used on early OBD2 engines. Not all OBD2 motors have that, but what I did on my 99 S52 was get an OBD1 head and have it machined to S52 spec and gain the extra sender hole.

[328ijunkie]

Also: Best way to do OBD2 IAT sensor is thread it into the OBD1 sensor port ;)

[Leo_328i]

Unfortunately not.