I have a 92 RS 305 TBI automatic with 149,000 miles, all stock & the engine seems to be running rich. The exhaust smells bad & when datalogging the BLM & INT always go down to 108 after it goes closed loop.

The car doesn't smoke at all & the car runs absolutey perfect, except that i can't pass emissions b/c of this rich issue.

All sensors tested good & they all work as normal when datalogging. Even though all sensors tested good, because of age i replaces all sensors (map, cts, iat, knock, new acdelco o2 sensor), new fuel pump & fuel filter, air filter, spark plugs & wires, cap & rotor, ignition coil, the throttlebody was rebuilt & the injectors were cleaned & are the correct ones for my engine. The intake was removed & cleaned & the egr works good as well.

All spark plugs are firing & the engine doesn't miss at all.
The fuel pressure is @ 11 psi & was also 11 psi with the old fuel pump as well. The engine vacuum at idle is about 21".

Ive owned the car for several years, & the exhaust has always smelled bad, but i used to live in a county that didn't have emissions testing, but now i live in an emissions county.

I took a video of the injectors spraying & the cone shape seems perfect, & while watching the video you can see the injectors pulsing on & off.

I check for fault codes often (& there are none) & it only flashes code 12.

The only thing that i can think of is that the ecm 1228746 may not be functioning correctly.

Any ideas?

 

Before replacing the ecm make sure the grounds are good, these can be at the back of the heads or t stat area. Make sure the ecm is getting the proper 12v & 5v signals too.
Make sure the map sensor is hooked to the proper connection or hook it to manifold vacuum (anywhere below the throttle plates).
Check the timing & make sure it advances when you rev it.
Do a resistence check on the cts. The resistence changes w/ temp, so you'll need to find the ohms/temp values on the web.

 

I'd think your IAC port was clogged.