Hey guys, My 92 Rs 305tbi is running rich.....i think.....i can smell unburned gas comming from the exhaust and the exhaust is smoking alittle bit more than usual. Also, the engine feels slightly underpowered. How can I adjust the Air/Fuel mixture with my TBI?
Thank you for any info you can give me.

 

Well you could have a multitue of problems. Do you have any mods as of now that would affect the stock prom from being way off? The first thing you should do is make sure that your car is not throwing any codes. A code will tell you what the problem is right away usually. You could also have clogged injectors that are dripping and not spraying into the TBI unit. Also a dirty TBI unit could cause problems as well. A quick fix would be to make your fuel pressure regulator adjustable. That is outlined in a tech article in the tech article section. Does the engine only feel underpowered now because of the rich condition?

 

Assuming everything is stock, its just parts going out of tune. An ALDL cable and winALDL is a wonderful combination for diagnosing what's wrong, but that aside, here are a few things I did to fix my rich issues:
1. New O2 sensor. Only $16
2. Adjust throttle position sensor. Some sensors have enongated bolt holes. If so, loosen it and rotate it ever so slightly counter clockwise. If yours doesn't have the elongated holes, you could try to enlarge them to give some play (Careful, I tried that - the plastic cracked, new ones ar $50).
3. Completely clean the TBI. The PCV passages are probably gunked up, and the IAC passages. Clogged IAC passages could make a rich idle
4. Set fuel pressure. The mod is free, but a guage to properly set pressure is about $20-40

Hope that helps.