My buddy has a 1990 CRX HF with a b18a1 bottom end, b18b1 top end with an 'a1 distributor that was modified to fit the 'b1 head, b18a1 5speed transmission, and a crx hf engine harness. He was using his buddy's PR4 temporarily until I could dig up my spare/tested & working PR4s.

Anyways, I gave him the first PR4 and it instantly gave him a Code 13 - Atmosphere Pressure. He gave it back, I tested it in my mostly stock '91 DB1 and had no issues. I sent him home with the second spare PR4, same problem. We can't figure out what the issue is, or why his buddy's PR4 isn't giving that same code.

Could it be the HF engine harness? Or the fact he's using a 'b1 head on an 'a1 setup in an obd-0 car? I've never heard of anyone using a b1 head+a1 distributor+hf harness like that before, and something tells me that could very well be the problem...could be sending a bad signal to the ecu which causes a false code 13 or something. What that doesn't explain is why his buddy's ecu isn't throwing the code...unless by some odd chance his buddy's PR4 ecu is different in some way, or a bad component in the ecu is keeping that particular code from being thrown.

Any and all advice is appreciated. Gotta get this issue figured out as soon as possible.

 

just curious, what did you have to "modify" on the b18a distributor? I had a b18b in my crx, kept it obd0 with a b18a distributor, and didn't have to "modify" anything. are you sure you don't have a b16 distributor? probably not the answer to your question, but i was just curious.

 

is the atmospheric (PA) sensor thats in the kick panel up and behind the ecu plugged in? maybe its gone bad for some reason?

 

He told me that he had to modify/weld a tab on the a1 distributor to get it to install properly on the b1 head. I've only seen the car twice, and didn't look at it well enough to know any more details than what he told me, which is in the first post.

In my years of working with integras and b-swaps, I have never heard of a swap like his(hf harness, a1 block, b1 head+a1 dizzy). To me that doesn't seem like it would work without issues. He says the HF harness is 100% identical to the 'a1 harness, is this true? From what I recall, it's not...but I may be wrong.

EDIT1: You kept the a1 distributor on the b1 head, and stayed obd-1? Those 'a1 distributors are obd-0...how does that work?

EDIT2: Isn't the atmospheric sensor in the ecu for most hondas? Also, if it's under the kick panel and malfunction or not plugged in...why is his buddy's pr4 not throwing the same code that both my pr4's threw? I honestly think it's because he's using an HF harness on a obd-0 a1 block / obd-1 b1 head / obd-0 a1 ecu.

 

the hf harness should be the same as the ls harness.
the a1 dizzy will bolt up to the b1 head and work without problems. the b1 head will work on the a1 block. i dont think there is a problem with the block/head/dizzy/ecu combo..

 

Should he be using an obd1 ecu since he has an obd1 head?

I just can't seem to figure out what the problem is. I've never heard of someone modifying an a1 dizzy to fit a b1 head which is bolted to an a1 block and wired together with an hf harness that runs to an a1 ecu...that sounds like it would cause more headaches than it's worth.

 

the b1 may have been ran with obd1 components at one time but it has nothing to do with how its being used now. the a1 dizzy will bolt right up to the b1 head. and as long as you're using an obd0 pr4 ecu with the obd0 dizzy and obd0 injectors, i don't see what the problem is.

And nope the pa sensor is not in the ecu. its in the kick panel.



The PA sensor, mounted inside the vehicle in the right kick panel area, is a silicon diaphragm type strain gauge sensor. It converts atmospheric pressure in the intake manifold to an electric signal and inputs that signal to the ECU. This signal is used by the ECU as a reference signal, and compares it to the signal from the MAP sensor to more accurately calculate the engine load condition.

 

What if he is actually using a b16 distributor like someone said above, and not an a1 distributor like he thinks? What if he's using the b1 injectors and manifold instead of the a1 injectors and manifold? Those two things I'm not clear on at this time, waiting for him to call me back and answer that stuff.

Those could be completely un-related to the code 13. It could very well be that the PA sensor is faulty, and the one PR4 not throwing the code 13 could be faulty in some odd way...meaning the two PR4s I gave him are operating correctly, and throwing a legit CEL.

I gave myself a headache over all this stuff, haha.

 

i mean it could be that he has the wrong diz on there, but even if thats the case the dizzy has nothing to do with the pa sensor. if he's using the b1 injectors with the resistor box still intact it wouldn't throw a code, it just wouldnt run right/or at all period.

 

Sorry i didn't see that i put obd1. It was kept obd0. I just had a typo. Corrected it in the original post.

They are not 100% identical but they are very similar.

 

I came to the conclusion that if 2 of 3 PR4 ECUs are giving the same CEL, that it HAS to be a bad atmos sensor. I told him to swap it out with a friend's to see if the problem goes away, and if it doesn't we'll go back to trying to figure out what the problem is.

If his buddy's ECU doesn't throw the code in his crx, but mine does...I may just see if he'll swap my ecu on his buddy's car. If that works, they can just do that and everyone stays happy.

 

the '90 - '91 B18A1s are OBD0, the '92 - '93 B18A1s are OBD1. Regardless I don't think this has anything to do with your buddys issue.