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So it is running rich, I would look into the EVAP purge solenoid by performing a purge and seal test with a scan tool. Or you could have a fuel injector leaking. The MAF or ECT sensors could be reading incorrectly also.
 

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Discussion Starter #5
So it is running rich, I would look into the EVAP purge solenoid by performing a purge and seal test with a scan tool. Or you could have a fuel injector leaking. The MAF or ECT sensors could be reading incorrectly also.
So far I've done the following (all of which I wanted to do anyway, just because I bought it used and wasn't sure when the last time any of this was done was);

Changed plugs
Changed MAF Sensor
Changed both Downstream O2s
Had exhaust regasketed, checked for leaks (I know this has nothing to do with the codes, just listing it anyway)

I just bought new injectors for it and am doing those this Sunday. I suspect that is the problem but regardless I wanted to change them out even if it's not. I did pick up a MAP sensor which was listed on ROCKAUTO under V6 G8. All OEM standard stuff, nothing aftermarket, which is what led me to believe it had one.

I DO have a Scan Tool (CEN-TECH 62119 Deluxe OBD II & CAN Scan Tool), not sure if it's capable of the function you mentioned. I will look into that.

The ECT sensor I have not touched and I haven't had any temp issues from what I could tell. She seems to get up to temp no problem and there's no fluctuations in the readout on the dash. But it's a cheap part so I could add that to my work this Sunday.
 

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Just make sure the ECT readings seem accurate, If It reads cooler than it should be it will over fuel the engine. Best just to check what it is reading before you start it up in the morning, the reading should be close to the same as ambient temp. If the EVAP purge valve is open when it shouldnt be it will pull excess fuel vapor and set a rich code. I have found this to be pretty common on the 3.6L V6s.
 

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Monitoring the Fuel Tank pressure sensor for excess vacuum or performing a purge and seal test will let you know if the purge valve is open when it shouldnt be.
 

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Discussion Starter #8
Monitoring the Fuel Tank pressure sensor for excess vacuum or performing a purge and seal test will let you know if the purge valve is open when it shouldnt be.
Okay, I took some live data. Maybe there's something of note in this, I'm not a mechanic so I don't know what the values for some of this should be.

Live Data - Google Doc

Can you tell me how to monitor the FTP Sensor?
 

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Would venture to say the problem you're experiencing is indicative of something further up in the system that provides information to both downstream sensors. Have never seen both catalytic converters nor downstream oxygen sensors go out on a vehicle although stranger things do happen. Moreover, since they are designed to worked independently of one another, the likelihood is even less probable. Likely culprits are a vacuum leak, defective map (manifold absolute pressure) or maf (mass airflow) sensor. Have you tried cleaning the mass airflow sensor? As far as the map sensor, couldn't locate it last night, but will give it another gander in the morning.
 

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Would venture to say the problem you're experiencing is indicative of something further up in the system that provides information to both downstream sensors. Have never seen both catalytic converters nor downstream oxygen sensors go out on a vehicle although stranger things do happen. Moreover, since they are designed to worked independently of one another, the likelihood is even less probable. Likely culprits are a vacuum leak, defective map (manifold absolute pressure) or maf (mass airflow) sensor. Have you tried cleaning the mass airflow sensor? As far as the map sensor, couldn't locate it last night, but will give it another gander in the morning.
I changed the MAF sensor completely. Honestly I thought the same things and was asking about the map location.
 

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What brand of mass airflow sensor did you use? Did you notice any differences after changing the sensor? The map sensor might be located somewhere around the intake manifold, but can't confirm or deny the notion.
 

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Discussion Starter #12
What brand of mass airflow sensor did you use? Did you notice any differences after changing the sensor? The map sensor might be located somewhere around the intake manifold, but can't confirm or deny the notion.
Bosch. Honestly I didn't notice any difference.
 

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Also I was able to purchase a MAP sensor listed under G8 v6. I have one sitting g here ready to use.
 

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Is the map sensor a Bosch as well? If replacing that doesn't do the trick then might want to thoroughly check for vacuum leaks. Do you hear hissing sounds while the car is running?
 

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Is the map sensor a Bosch as well? If replacing that doesn't do the trick then might want to thoroughly check for vacuum leaks. Do you hear hissing sounds while the car is running?
The map is yes. Noni do not hear any hissing sounds and the engine does not act like there's a vacuum leak. For example I do not see RPM fluctuations or anything of that sort. I personally ally was suspecting the injectors and am changing those this Sunday. But the Map sensor is another suspicion. I'm honestly hoping it's the MAP or injectors.
 

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Very well. Oftentimes, the sound a broken or cracked vacuum line makes is barely audible and depending on its location may not significantly impact the performance of an engine. Don't recommend continuing to throw parts on the car if there is a competent repair facility nearby with both the knowledge and equipment necessary to properly diagnose the vehicle. However, if there are not any viable local options or thus far they have proven themselves incompetent, then at least you're narrowing down the range of possibilities . At any rate, best of fortune resolving your issues and be sure to update the thread regarding any progress. Will report back if able to locate the manifold absolute pressure sensor.
 

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Very well. Oftentimes, the sound a broken or cracked vacuum line makes is barely audible and depending on its location may not significantly impact the performance of an engine. Don't recommend continuing to throw parts on the car if there is a competent repair facility nearby with both the knowledge and equipment necessary to properly diagnose the vehicle. However, if there are not any viable local options or thus far they have proven themselves incompetent, then at least you're narrowing down the range of possibilities . At any rate, best of fortune resolving your issues and be sure to update the thread regarding any progress. Will report back if able to locate the manifold absolute pressure sensor.
Oh. Well I'm am amateur and I was under the impression that vacuum leaks would should rpms fluctuations. I am absolutely open to the possibility it's a leak. As far as throwing parts at it so far the parts have been cheap fixes so I don't mind. Honestly I bought the car used a couple years back and I wanted to change the injectors anyway. I've done the plugs and a few minor things so far. There isn't a shop local I honestly trust. :(
 

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Am not anywhere near a professional and even they can and have been wrong. Recently, just proved two wrong, but in the past they have proven me wrong. Automobile repair work is not an exact science as one must take into account a variety of variables. Have yet to meet a man or woman who/m is always right and suppose I never will.
 

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Am not anywhere near a professional and even they can and have been wrong. Recently, just proved two wrong, but in the past they have proven me wrong. Automobile repair work is not an exact science as one must take into account a variety of variables. Have yet to meet a man or woman who/m is always right and suppose I never will.
My main issues with mechanics near me has been the fact that they're just looking to sell as much as possible. I've caught mechanics in lies through my own research. I've seen them ignore diagnostic processes only to tell me there was a major issue with my vehicle, upon taking it to another place and telling them what happened finding that the fix was a simple $40 fix. This actually happened with my exhaust.

Anyway, I know no one's perfect but I am finding that self-learning is far more lucrative than trusting mechanics or dealerships. I trust you guys more and I've never seen your faces. lol
 

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Reading the service manual, shows that your engine *does not* use a MAP sensor. Your engine uses a tricked out MAF sensor. It contains 2 IAT sensors within it. The ECM measures the temp of the air as it passes the first sensor (that has a thin film heater circuit as part if it). The second IAT sensor captures the now heated air temp, an sends that signal back to the ECM. The ECM needs, and expects to see this action, to properly measure that temp an total air flow thru it. That action helps the ECM accurately calculate what the correct injector pulse pattern should be, for precise fuel control under all conditions. *There is*, a trick solenoid (Intake Manifold Runner Control Solenoid) installed at the back end of the upper manifold section. It (on command from the ECM), will be cycled to change the manifold from a big volume manifold, into 2 separate smaller volume manifolds. They say this action allows the engine to perform at its best thru its entire power range (so to speak). Now maybe some other version of this engine uses a MAP, but not yours. My thinking, is that maybe you got your hands on a MAP sensor for the V8.
 
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