Is there any real difference between an OBD2a and an OBD2b Y8 intake manifold? Will any junkyard 96-00 intake mani work?

And for my turbo project, is it going to matter if the head itself is OBD2a or OBD2b? I found out that the head, which was in a 99, originally came from a 96. Will that change anything drastically for my boost project?

 

I'm not positive, but I think all that matters is that you have the correct conversion harness to OBD1. Once your there, its all just in the ECU.

 

^what? he isn't using a obd1 head or ecu. no they should be exactly the same.

 

What is he going to be tuning with then? If he is boosting, he will most likely be converting to an OBD1 ECU that will be chipped.

 

I found out the hard way, during my motor swap, that 96-98 IMs are NOT the same as 99-00. They appear to be in almost every aspect, but they ARE different.

The 99-00 Manifolds have an extra air injection system built into them, with these tiny little ports that WILL leak air and cause ridiculous idle surge if you try to attach it to anything other than an OBD2b head.

Here is a pic of the air injection holes.




I ended up bringing mine to a local welding shop and having them seal up the holes. Took em 15 minutes and I was back in business, idle surge free, shortly after.

 

DUDE!!!!!!!!!!!!!!!!! You just figured out what the intake leak is on my car! It's a 96 head(/block) with a 2K intake. There must not be any air injection holes on the head! A little bit of RTV made it better but it's still funky. Welder time next weekend! Score!

 

BOOM! I don't know why this knowledge isn't more common. I had an absolute HELL of a time figuring it out a few years ago.

Definitely weld it, anything else you risk having portions break off and end up inside your head.

 

Yeah it drives you nuts! My car has been like this for almost a year. I've been over every vacuum line 2-3 times, cleaned the IAC valve, replaced the IM gasket with added RTV all the have the issue persist.

How did you figure it out?

 

Trial and error during my motor swap (dropped a z6 into a '99 EX using mostly all y8 parts). What it boiled down to was listening with a stethoscope to figure out where the air was rushing out, and narrowing it further from there.

 

So if I use a 96-98 y8 intake on my 96-98 head, but use the 99-00 engine wiring harness...? It should be okay because I'll have the OBD2b to OBD1 conversion with a chipped P28 ECU?