kevmi44

I am using an OBDI to OBD II wiring harness to use the JDM p73 ecu that came with the motor swap. I am getting a backfiring sound once in a while from the exhaust. I upgraded the fuel pump and injectors to ones from a 94 GSR. I'm also using a distributor from a 94 GSR so that the OBDI engine bay wiring harness would plug into the sockets for the injectors and distributor.

I'm wondering, is the backfiring/detonation sound due to the JDM ecu being tuned for the higher octane gas in Japan or is there something else that I'm overlooking? I did a search and could not find any info on this topic. Can't seem to think of any other possibilities. The sound occurs mainly when cruising.

Thanks in advance for your help!

RuffRhyno

backfiring could just be normal...hell my D16Z6 backfires on my 2 1/4" exhaust with no cat. It is mainly caused from either accelerating to suddenly letting off of the throttle, or if the engine is trying to decelerate. Unless you notice a power loss, don't worry about it. It's normal.

crvtt96

I've also done JDM '97 B18C OBD2 swap into '92 Civic HB VX recently , and have a check engine light come on after driving a short distance, when the light is on there is an occational backfire in (from) the exhuast which is due to being to rich at that time..I think.... Does your CEL work , does it come on ? Mine does not display any code so I'm still working it out.

kevmi44

I do get a CEL. It does not blink, just comes on solid every time I start the engine. I believe it is because I have no O2 sensor on the catalytic converter.

bossman032

umm maybe its your wiring.

who did your wiring ur check engine light should blink when u jump the connection..

kevmi44

Another factor could be the JDM Si-R cluster that I have as well. But I'm pretty sure its because I do not have one of my O2 sensors connected.

Greasemonkey

Why don't you try to plug connect the datalink connector so see what type of code it throws.

The CEL will only blink to tell you what code it is when you plug in the connector. If you have no O2 in your CAT then that is definately one of the reason why it is throwing a CEL.
Also there could be more then one code so be patient and write down all the code and see what they are. Could be more then one problem.

Greasemonkey

Do you have a CAT on your car? When you have CEL you are on Limp mode. Meaning you will run rich and it you have a cat, it will eventually burn your CAT up.

So fix all of your CEL..

Katman

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Greasemonkey &raquo;</TD></TR><TR><TD CLASS="quote">Do you have a CAT on your car? When you have CEL you are on Limp mode. Meaning you will run rich and it you have a cat, it will eventually burn your CAT up.

So fix all of your CEL..</TD></TR></TABLE>

and to add to this...

A JDM ITR ecu is tuned for higher octane petrol, so indeed the detonation could very well be due to the ecu programming, ignition timing settings. Have you checked your ignition timing at all either? should have it set somewhere between 16-18 degrees, anything higher will cause pinging (which might be one of your problems), anything lower (way lower) will rob horsepower.

kevmi44

I do not have a cat on my car.

I did have a feeling that the JDM computer was tuned for higher octane gas. I haven't checked my timing yet either. I'm on the verge of getting a Hondata s200 unit and BC Spec III cams in a week or so. I'll check the timing then...

Thanks for your help guys.

crvtt96

I was told that the JDM ECU (jap. spec.) does not use the secound O2 sensor in/after the cat. like US ones ... I'm not sure though. Please let me/us know how the hondata goes !