So the only mechanic I trust looks at my 89 auto 305tpi iroc and it's codes (45) with a plugged up exhaust. I've been running rich for a while, have all new sensors / ecm / prom in my car, new cap/rotor/plugs/wires you NAME it. He really believes that I have a misfire in the engine which is causing it to run rich and needs a rebuild eventually. I don't want to change out the exhaust now and just plug it up again.

Is there anyhting I can do to lean out the mixture in my car, to kinda cheat out the rich condition made by my engine? I don't want to rebuild just yet, and the car runs pretty well actually besides the slight richness.

ANy tips?

Thanks,
Layne
www.laynethrasher.com

 

The "richness" on an efi motor can be caused by an exhaust leak. (near or up stream from the o2 sensor) The exhaust can be sucking air (extra o2)
fooling ther computer into thinking it needs to enrichen the mixture. A leaky injuector can cause a pesky rich mix too.

couple thing to check for........

 

Thanks for the advice, the injectors and fine, they've been cleaned as has the throttle body. The motor seems to have a slight misfire which is causing it to run rich. Is there anything I can do to lean out my mixture?

 

A plugged up exhaust isn't helping anything.

In a word....no

So long as there's fuel being sprayed into a cylinder, and it's not firing, you'll have a rich exhaust.

Why's it misfiring?? You need to find out why.