OBD1 in EM1 Working Sometimes

firejackal

New Member
5+ Year Member
I have a EM1, which has it's B16A2, and OBD2B (P2T) ecu, recently my catalyic converter rusted off, so to not worry about the cels that come with running a straight pipe (catalyst below threshold) I decided to go back to using OBD1 (which I had problems doing before) so now I'm going to try to get your guys help.

Here is the story and symptoms:
I know a tuner who got the ECU ready for me with the correct basemap, the ecu works fine in his cars with the same engine and so forth, so it's not really an ECU issue I would think.
Some times the ECU will work fine in the car, no problems. But then sometimes randomly when turning on the car, the main relay won't engage (new relay, engages fine with the P2T ECU), meaning it won't click on then click off. Shows a solid CEL (usually a solid CEL means the car can't communicate with the ECU correct?).
When I try to start the car anyways, it starts, then dies approx 1 to 1.2 seconds later, but it dies as if I turned the key off.
I don't have the brand on hand of the jumper harness, it's a red harness with one side glued. It's the second harness I went through, the first harness was a generic ebay one which did not have a working tach. I have another one on order to verify wiring.

So back to the story, the main relay won't engage, so the fuel won't prime, starving the engine when starting... once i turn off the key, then back on to the 2nd position X amount of times, then it works and no CEL. There is no short, everything is fine during driving, it's just when turning on. It can either be a cold or warm start (in the morning, or when getting gas.)

If anyone has any clues, or maybe a lead, or maybe even experienced this, I'll be grateful hearing from you guys. For now I have to stand getting use to this CEL. (for OBD2 means, i have a bluetooth adapter to read/clear it.)
 

firejackal

New Member
5+ Year Member
Bump, and I'll change the question a bit...
Does any one know how obd1 and obd2 different on turning the main (fuel) relay, and how it decides to turn it off? Either the wiring harness is messed up or something is more sensitive on obd1, I just can't figure it out, still waiting on new wiring harness.

Sent from my SGH-T999 using Tapatalk 2
 


ReedMann

New Member
Registered VIP
5+ Year Member
If you know that everything works fine with the OBD2 ECU and you know that the OBD1 ECU works, then the only place for a problem to arise would be in the jumper harness.
 


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