My 92Z 305 TPI auto all stock has run a little rich especially when cold since I bought her. Once and a while on a very cold morning she might even start to load up, Over all it runs great, only about 12MPG though, when I get after her from a dead stop, sometimes will get a little black out the pipes, no stumble or hesitation and the oil stays nice and clean so I haven’t worry too much about it but like all cars she is telling me something is off. If it never came out of closed loop won’t the fast idle stay up? Is the ninth injector leaking a possibility? Any input will be helpful. Jim

 

You do not have a 9th injector. If the computer doesnt go to closed loop, it will use the fuel charts to determine the mixture. If it gets to closed loop, the computer will adjust the injector pulse width to adjust the mixture according to the sensors.

Id recommend hooking up to tunerpro rt and verify the system gets to closed loop.

The idle will not be high if stuck in open loop.

 

I guess it's time to learn about my TPI system. Thanks for the advise. Jim