I have a stock 86 NA motor with all the emissions delete, still using the BAC and TB thermowax, and for some reason I have my AWS still intact, the TB has had the secondary butterflies removed. Also have a pacesetter header and no cats, running premix with no OMP.

The issue I am having is when the motor is partially warmed up (temp gauge just in normal range, but not up to full temperature). What happens is when I am driving and coming to a stop with the throttle closed and clutch engaged, engine braking, when I disengage the clutch, the RPM's drop to 500RPM or lower and sometimes it will stall, and it starts right back up, if it does not stall, it takes a second, and the BAC opens to bring the idle up to 1000RPM, then drops to 700-800RPM steady idle. If I unplug the BAC when the engine is up to temp my RPM is 700-800RPM, which is normal. When the engine is cold and still on high idle, it will not do this, and when warm it will do this, but the RPM's go down to maybe 500-600 for a second, but it will not stall.

If I do not engine brake and put it into neutral right away, the RPM's drop to idle speed and stay there, same if I rev it up in neutral. My theory is that I have a leaky injector or something causing an over-fueling situation, because I assume the stock ECM cuts spark and fuel when the TPS is reading idle position and engine RPM is high, if I have an injector still dribbling, it wont be getting burned, where if the RPM goes right to idle, its firing the fuel injectors and spark plugs, burning it off.

I had my injectors tested and cleaned before I installed this motor in April of this year, and 2 injectors did not require cleaning (1 primary and 1 secondary), but one injector had a poor spray pattern and needed cleaning, the other injector was stuck open and had a poor spray pattern, they were both rebuilt and working good, but maybe its not working again?

I have checked and adjusted both of the thermowax settings on the TB, and it is fully releasing off of the cam, and my cold start idle is 1550RPM with the BAC unplugged. I do have my dashpot removed so I can adjust my thermowax settings and other TB settings easily, but it will go back on when its working good. The TB on this motor has been modified, both throttle stops have been adjusted as they no longer have a silicone blob on them to stop tampering, so it may be a TB setting that's out.

Would this be a side effect of the emissions delete, or is something else going on?

 

If it does it w/the dashpot removed then reinstall the item as it prevents the secondary throttle plates from closing too quickly on deceleration which can choke off the engine. Also check the clutch switch to make sure the voltage is 12 volts w/the clutch depressed. The Yellow/Blue wire runs to the ECU to tell it that the clutch is being depressed and the ECU makes a compensating adjustment.

 

That may have something to do with it, I just went to probe the ecu wiring, and I have no wire in the clutch switch location. This motor is in a B2200, I did the swap over winter, and a GXL RX7 has a million more options than my truck, I would have removed it thinking it was for cruise. I guess I will have to run a wire to that spot on the computer and see if it solves it, I remember being confused at the excess wiring for the brake and clutch switches going to the ECM with a diode in between the switches, but most went to the cruise module so that is why it was removed.

EDIT: I looked at the B2200 diagram, and it is completely opposite to the RX7, the clutch switch grounds a pin on the ECU when the clutch is engaged (pedal up), and it is also tied into the neutral switch. I remember keeping the wiring the same as the B2200 because of the lack of cruise. Looks like I have to dig around for the RX7 clutch switch, and re-wire the entire setup lol. Yay