Hi Scotty,
Owned it since I had it built in 1998. Only driven in summers and I now have 145k on it. Automatic with the GM 3800 engine. No mods outside of a Borla Exhaust. For the last couple years the engine light will come on but intermittently. When I plug in my scan tool it tells me engine is running rich. I have changed wires/plugs/ignition coils around 2 or 3 times in the life of the car. When I look at the readings on my tool it tells me; short term fuel1 -5.5% Short term fuel2 -7%. Long term banks 1 and 2 are at -22.7% each. My 02 sensors (of which there are 3) voltage are all pretty close, .825v/.0680v/.720v. So I'm thinking it's not them.
Just watched your video on the Colorado. Do you think it could be the plugs? Thing is I don't have a ton of miles on them. I will also say I never changed the fuel injectors out, but I have had the fuel system cleaning done on the car around 3 or 4 times in its life.
Thanks for any insight!
Kevin
Have you ever checked the air filter? You failed to mention whether or not that has ever been changed, and it will definitely run rich if it's clogged.
Absolutely. I have a K&N in it. The thought occurred to me that if it's over oiled it might cause this. I may try getting a cheap paper one and drive it a bit to test.
That will definitely cause it to run rich. You could have oiled your MAF sensor.
Had just enough time between rain storms to clean the MAF. When I got it back in and idled in the drive it seems the short term was holding right at 0 and not budging. I didn't get to actually go for a drive though before the rain came in, but it's looking promising!
Does your ECT, IAT, MAP, and MAF, sensor live data look right?
If so, what happens to those fuel trims if you run the engine with the MAF sensor unplugged. (This will set a MAF Sensor circuit code but you can erase the code after the experiment).
See if those fuel trims change when you take it off of mass airflow and force it to use speed density
Worth a try! I just bought some MAF cleaner and was going to clean it anyway.