My 87 FC missfires constantly when it is idling cold, but as soon as it goes closed loop seeral minutes after starting it cold, you can suddenly hear the transition in the exhaust note and it totally smooths out and does not miss at all. It has strong 100+ psi compression on all 6 individual rotor pulses. What would make open loop run funky and then closed loop is totally smooth? It's funny, you can tell when it goes closed loop because it will be idling sounding like an old piece of junk, and then the idle speed raises just slightly and you can here it suddenly go smooth.

Does this have something to do with the variable resistor adjustment?

Thanks

Steve

 

Have you tried adjusting the variable resistor? Don't really think this needs to be adjusted. Is your car totally stock?

My guess is that it is running rich while warming up (for some reason, there are plenty to choose from), and when it switches to closed loop, it makes adjustments to the fuel, to meet the O2 sensor requirements.

If you fiddled with the variable resistor, this is the place to start. If not, there are many other things to try.

 

i would start with the TPS and variable resistor adjustments, like in the FSM. also you might wanna look at the bac valve hose to the TID, if there is a leak there, it can do strange things to the idle control

 

car is stock, i have not touched the variable resistor adjustment yet I just saw that come up in some of my reading.

BAC hose to TID can you clarify? Thanks

Steve