befarrer

iTrader: (1)

Hi, I just registered here, so first post, feel free to move it if its not in the correct forum.

Anyway, I just installed a 1986 13B non turbo in my 93 B2200 which had factory EFI, the motor runs and seems to be operating correctly, however, my BAC is opening all the way as soon as I turn the ignition on, I can hear it buzzing with ignition on engine off. The BAC is working, it closes if I unplug it, or turn off the ignition, and it is getting an AC or pulsing signal from the ECM (not a 12V DC indicating a crossed wire), but even when the engine is fully warmed up, I have an idle speed of about 3,000RPM or higher. If I unplug the BAC or jumper the test port thing to set idle, my idle is steady at 750 like the service manual says. My throttle body thermopellet is working correctly, and the TPS is set according to the manual. What could be causing the ECM to want the BAC wide open? I have tried 2 different ECU's, 2 different BAC valves, I have tested all wiring to the computer for the sensors, and they are correct, all sensors are putting out the correct resistance too.

Some background, I bought this motor and car as a running car, it ran fine before, was bone stock. I have removed the emissions stuff under the intake, EGR is removed, air pump removed, oil injection removed (using premix), had injectors flow tested and cleaned, using the B2200 EFI fuel pump and radiator (no radiator temp switch), also using the B2200 gauge cluster, I installed a pacesetter header, and until I can figure out a 5/6 port activation method, I have the ports wired open. I am using an intake manifold and throttle body off of a parts motor I bought of the same year.

I am thinking for right now to just remove the BAC and run it without, but I would like it operational since I am from Canada and it gets cold here, and I would like to be able to drive it year round.

What does the stock Mazda ECU use to control fuel ratio on these motors? The coolant temp sensor, air flow sensor (all wires), intake air temp (on intake), vac sensor, and ambient pressure sensor all have 0 ohms to the correct terminal on the ECU and all of the sensors are working, so I would think I am not running in some enriched fuel mode.

satch

iTrader: (1)

The wire which runs from the ECU to the BAC sends a ground to activate the BAC. The lower the voltage the more it invigorates the BAC. W/key to start the voltage reading should drop to about 2 volts or so which causes the BAC to pulse wide open more than when the voltage is not as high.

befarrer

iTrader: (1)

I checked my wiring, and across both terminals at the BAC valve, I am getting 10.4V with the ignition on, and engine off. I am getting battery voltage at one terminal with the ignition on, and the other terminal goes back to the ECU. Now that I have my tach hooked up, my engine RPM is 2500RPM all the time when the BAC is hooked up.

satch

iTrader: (1)

What's important is what happens w/key to start or w/the engine running and not w/key to on and engine off. The B/W wire powers the solenoid so it should have close to 12 volts either w/key to on and engine off or w/the car running (this wire does not control the BAC so your focus needs to be on the other wire). The other wire though is the key as it is what controls the degree as to which the solenoid works. So, this wire needs to be measured w/the key to on and engine idling. Again, the lower the voltage on the wire from the ECU the more the solenoid is activated.

befarrer

iTrader: (1)

Hmm, I replied to this but it appears I didnt hit send. Oh well, thank you for the responce, but I have found my problem. The start wire going to the ECU from the starter, which tells the ECU the engine is cranking over was hooked up to ignition, so the ECU thought it was starting, and holding the BAC open, and probably dumping fuel in. I changed that so it got 12V during cranking only like it should, and all works fine now.

Just put insurance on it. Loud as %@^$, I have a pacesetter header, 2ft of pipe and a single magnaflow muffler with a resonater tip shoved in the end for now untill I get around to pulling the box off to fabricate the rest of the exhaust along with a second muffler, the exhaust exits just behind the drivers seat right now.