i was wondering if my car is showing signs of running lean or rich? It puffs out black smoke only when i really get on it and in between switching gears (It's a M6). It also pops or backfires every once in awhile while just sitting and idling and sometimes the SES light will come on for like 10 seconds then it will go off, so i cant just scan it. any input would be greatly appreciated! thanks guys!

 

Sounds like your running rich due to a bad 02 sensor with maybe a exhaust leak. When does the SES light come on at? I had something like that when at idle my SES light will come on, but once you start driving it will go away. Found out passenger side 02, and a exhaust gasket leak at the converter flange.

Vinny

 

it comes on when i am just sitting and idling only for a split second then goes away and it has only happened a couple of times. I do have a minor exhuast leaxk from the AIR fitting that goes into the manifold. would that really cause it to run rich?

 

would the leak from the air fitting on the manifold cause the o2 sensor to go bad?

 

Maybe... The air fitting are to fwd of the 02's. My leak was at the flange by the passenger 02. If extra air is getting suck into the exhaust it will send funning reading to the 02 for extra/less fuel.

 

I had those sme issues.. minus the smoke... it was ocassional misfires and bad 02's .... I wouldnt say the 02's signal my SES light... and trust me these things were f34ked! It was the missfiring... caused by junk Spark plugs... changed then out no more misfiring.

 

You can still scan it. Once the SES light comes on, the code that caused it is stored in the PCM, even if the problem disappears and the SES light goes off.

While scanning, check the long term fuel corrections (BLM's) to see if the PCM is possibly adding extra fuel the engine doesn't need, in response to a "false" lean condition - caused by misfires, leaking exhaust before the O2 sensors, or a faulty sensor.

 

i just scanned my car and i got code 23 which is MAT low and i got code 77 fan fault but thats probably b/c i added a fan switch to the relay b/c they both come on when i flip the switch. What could be causing code 23 MAT low? My long term blms start at 128 then drop to 108 80 seconds in. and all 4 boxes for long term counts and short term counts are pink in datamaster, any help is appreciated Injuneer or anyone else.

 

DTC 23 = Intake Air Temperature (IAT) sensor circuit (signal voltage high, low temperature indicated)

Generally means the sensor is showing infinite resistance = -40degF. Is it possible you have a loose harness wire on the sensor.

That shouldn't cause the BLM's to drop to 108. You are either running EXTREMELY rich, or you have something causing the PCM to think its running rich. Its pulling the max allowable fuel (15%) and the O2 sensors are still telling the PCM its rich. I'm surprised you don't also have DTC 45 and 65.

 

nope those are the only codes i get. You are right, the datamaster run showed that the temp was -40 degrees. I have a spare iat sensor, could i put that in or is it in the wiring harness itself?