[Xiao_Hu]

Hey guys,

I've realized I have a little bit of a problem here. My 1991 Honda Prelude SI ALB was titled and its VIN indicates its not a 2.0SI. However I do not have a B21a1 engine but a B20A5 according to the serial number of the engine ( I bought the car knowing it wasn't the original engine ). So I need to figure out if I'm OBD1 or OBD0 because I don't know if they swapped the harness. What is an easy way to tell?

 

[Andrew]

O2 sensor(s). OBD0 has two in the exhaust manifold clearly visible from the front. OBD1 has one in the downpipe behind the oil pan.

 

[cudaboy]

easiest and what recommend is to retain the harness and computer and drop the b20a5 in using the b21a1 intake manifold and exhaust manifold and downpipe. That is probably what you have if it is running right and still has its original ecu. The other way is your intake manifold should just be two piece. The b20a5 is two piece as well but it has about a 1" tall butterfly plate sandwiched between the top and bottom pieces. It is for the secondary runners on the b20a5. The top piece being what the throttle body bolts up to. If it was a jdm b20a it would be stamped "b20a" and if they had the jdm intake manifold installed on it, it would not have an egr on the intake manifold.

There are other things you can check if you want to. If you want you can pull the carpet back after taking loose the kick panel and door sill plate and check ecu part number. I think the obd1 b21a1 has pk3 but I am not positive on this has I never focused on this info. I think the obdo b20a5 has a pk2 or pk1. Like said a quick search here in 3rd gen section will tell you or I am sure someone will chime in and correct me if I am wrong or elaborate. The part number on places like http://hondapartsnow.com or since your back east http://bernardiparts.com out of boston. I just got an email from them today because I once bought from them. Honda is raising its parts prices across the board of parts again effective April 1st. Majestic is out of rhode island http://www.hondaautomotiveparts.com but I never used them but plenty have over the years. They didn't use to use Honda official part numbers. I think that has changed if they are still in business. Anyway I digress. Tutor over.

 

[Xiao_Hu]

easiest and what recommend is to retain the harness and computer and drop the b20a5 in using the b21a1 intake manifold and exhaust manifold and downpipe. That is probably what you have if it is running right and still has its original ecu. The other way is your intake manifold should just be two piece. The b20a5 is two piece as well but it has about a 1" tall butterfly plate sandwiched between the top and bottom pieces. It is for the secondary runners on the b20a5. The top piece being what the throttle body bolts up to. If it was a jdm b20a it would be stamped "b20a" and if they had the jdm intake manifold installed on it, it would not have an egr on the intake manifold.

There are other things you can check if you want to. If you want you can pull the carpet back after taking loose the kick panel and door sill plate and check ecu part number. I think the obd1 b21a1 has pk3 but I am not positive on this has I never focused on this info. I think the obdo b20a5 has a pk2 or pk1. Like said a quick search here in 3rd gen section will tell you or I am sure someone will chime in and correct me if I am wrong or elaborate. The part number on places like http://hondapartsnow.com or since your back east http://bernardiparts.com out of boston. I just got an email from them today because I once bought from them. Honda is raising its parts prices across the board of parts again effective April 1st. Majestic is out of rhode island http://www.hondaautomotiveparts.com but I never used them but plenty have over the years. They didn't use to use Honda official part numbers. I think that has changed if they are still in business. Anyway I digress. Tutor over.

No the car already came like this. Judging from the lack of O2 sensors on the exhaust, it looks to be OBD1.

 

[Andrew]

That makes sense for an SI.

 

[Xiao_Hu]

Guessing the previous owner swapped either a USDM or JDM B20A5 into it. I'll do some research to find out which.

 

[1funryd]

Another way to determine is pull the carpet back from the passenger footwell and take a look at the plugs into the ECU.

If it has 3 plugs vs the OBD0 2 plugs then its OBD1.

OBD0 looks like this:

OBD1 looks like this:

 

[Xiao_Hu]

So doing more research:

I have an OBD1 Prelude, with a B20A5 from Japan, a B21A1 manifold with EGR and it somehow all works.

Well anyways, it is what it is! I like it.

 

[cudaboy]

If your engine stamp is b20a it is jdm. If it is b20a5 stamp it is usdm.

 

[Xiao_Hu]

If your engine stamp is b20a it is jdm. If it is b20a5 stamp it is usdm.

Mmmhmm. Its a B20A stamp - so its JDM.

I'm probably gonna keep the EGR system just because, it still works no problem, and it keeps the combustion chamber peak heat down.

 

[luzer]

So doing more research:

I have an OBD1 Prelude, with a B20A5 from Japan, a B21A1 manifold with EGR and it somehow all works.

Well anyways, it is what it is! I like it.

That would be the normal configuration for this swap, whether going with a JDM b20a or a USDM b20a5. Original intake and exhaust manifolds slapped onto the b20a engine. It's the easiest way to do this swap because you don't have to change any wiring or sensors, and you can still pass local emissions testing if required.

 

[Xiao_Hu]

That would be the normal configuration for this swap, whether going with a JDM b20a or a USDM b20a5. Original intake and exhaust manifolds slapped onto the b20a engine. It's the easiest way to do this swap because you don't have to change any wiring or sensors, and you can still pass local emissions testing if required.

25-years old in VA, no safety inspection if registered antique. I plan to register it antique when drivable on the road again. But VA is awesome.

 

[luzer]

25-years old in VA, no safety inspection if registered antique. I plan to register it antique when drivable on the road again. But VA is awesome.

Safety inspections aren't required here regardless of how old the car is. No emission testing either. I'm very happy we don't do emissions, but I think there are quite a few cars around here that should have a safety inspection.

 

[Xiao_Hu]

Safety inspections aren't required here regardless of how old the car is. No emission testing either. I'm very happy we don't do emissions, but I think there are quite a few cars around here that should have a safety inspection.

Don't wish it on yourselves. They fail your car if you have an aftermarket steering wheel, exhaust that doesn't "Look stock" ( that's not an exaggeration, that's the exact wording of the statute ) if your camber is beyond a certain number of degrees, and the most mundane stuff like if you don't have a passenger seat or back seat your car was equipped with.

 

[luzer]

Don't wish it on yourselves. They fail your car if you have an aftermarket steering wheel, exhaust that doesn't "Look stock" ( that's not an exaggeration, that's the exact wording of the statute ) if your camber is beyond a certain number of degrees, and the most mundane stuff like if you don't have a passenger seat or back seat your car was equipped with.

I'm not wishing what you have on myself, but there should be a minimum standard for allowing cars to be on a public road. The problem is exactly what those minimum standards should be. It amazes me the condition of some of the cars here. Exhaust systems ready to fall off on the next pot hole, bald tires, wheels that are obviously bent, brakes that sound like an anvil being dragged through a steel pipe, etc... Those kinds of things put others besides just the driver at risk.

It sounds like what they test for in VA is overkill, and more than just safety issues. Seems more like a method to discourage people from working on or modifying their own cars. And that's not what any backyard mechanic wants. What is kind of funny to me about your state is that some of the worst offending cars on the road are more than 25 years old, and you can get an exemption once it reaches that age simply by registering it as an antique.

 

[Xiao_Hu]

>What is kind of funny to me about your state is that some of the worst offending cars on the road are more than 25 years old, and you can get an exemption once it reaches that age simply by registering it as an antique.

In order to register as antique you must have another car insured, registered and titled in Virginia driving on the road that has passed safety inspection - also if that car happens to be an antique as well, it has to pass inspection.

 

[luzer]

In order to register as antique you must have another car insured, registered and titled in Virginia driving on the road that has passed safety inspection - also if that car happens to be an antique as well, it has to pass inspection.

The laws in this state just get more interesting by the minute. How does having one car that passes a safety inspection have anything to with another car that may not pass, but because it's more than 25 years old you were able to register it as an antique, exempting it from safety testing? :lol: Do they assume that you'll just drive the newer car more, thereby keeping the potentially unsafe car off the road?

 

[Xiao_Hu]

The laws in this state just get more interesting by the minute. How does having one car that passes a safety inspection have anything to with another car that may not pass, but because it's more than 25 years old you were able to register it as an antique, exempting it from safety testing? :lol: Do they assume that you'll just drive the newer car more, thereby keeping the potentially unsafe car off the road?

Its to prevent people from driving the 25-year old jalopy as a DD

 

[cudaboy]

I remember seeing a news article in last couple years that Virginia was considering or passed a law banning rubber scrotum sack commonly found on back of some trucks added by the owner.

 

[luzer]

Its to prevent people from driving the 25-year old jalopy as a DD

Shows how disconnected lawmakers are. That's not preventing anything. What if you're married and your wife drives the new car? Or, like me...I have three vehicles, two of which are a lot less than 25 years old. I drive the Prelude about 50% of the time as a DD. Just because someone has newer vehicles doesn't mean they're going to drive them more than the 25 year old car.

I remember seeing a news article in last couple years that Virginia was considering or passed a law banning rubber scrotum sack commonly found on back of some trucks added by the owner.

What about the chrome ones Kevin??? :lol: