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Discussion Starter #41
....and then realized something, when I changed my maf I also cleaned my throttle body with the crc throttle body cleaner and I remember something about messing it up if you push the blade in with your hand to clean it. So I took the cai off and checked around for left over residue, disconnected the negative battery cable for 38min. Put cai back on. Started for 3 min. Turned off a min started back for 3 min. Hoping maybe it does the relearn for tb position...
Unlike the G8 V6, the GT doesn't have a do-it-yourself at home no special tools required relearn procedure and believe reprogramming requires a Tech II or equivalent.
Ok well when I take it back to gm I'm going to have them do a compression test and a relearn on the tb.
 

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Ok well when I take it back to gm I'm going to have them do a compression test and a relearn on the tb.
Well, at this point, they would have to explain why have I spent in excess of $330 to supposedly fix a problem which still exist? In lieu of suggesting a compression test and throttle body relearn would ask which tests were performed the first go around? Bear in mind, you are paying them to fix the problem so let them to tell you what is wrong with the vehicle.
 

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to much air ,,, vacume leak on the intake ,, check hoses and clamps ,, check at the the maf sensor intake tube
 

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...They mean you have a vacuum leak somewhere, or an exhaust leak pre catalysts. Exhaust and intake leaks are not always audible, especially with a louder aftemarket exhaust. A vacuum leak could ALSO be present in your PCV system if its not sealed, installed, routed correctly or pulling air from in front of the MAF. Now I'm not saying any of this is your issue, but if it were my car, Id dig deeper and check these things.
to much air ,,, vacume leak on the intake ,, check hoses and clamps ,, check at the the maf sensor intake tube
Come to think of it, if the throttle body was indeed the culprit, wouldn't it produce some sort of check engine code? Both P0171 (bank 1) and P0174 (bank 2) are lean codes indicating too much oxygen and not enough fuel is being introduced to the system which mirrors the above two theories of something feeding both sides of the engine causing it to run lean. Agree check for vacuum leaks which are sometimes difficult to pin-point given the noise produced in the engine bay. Some people spray a solvent on various hoses then listen and watch for fluctuations in the engine's revolution per minutes to help track down suck a leak. Either way, would suggest thoroughly checking the aforementioned items as the next step in troubleshooting. If you are able to find the problem, wouldn't fix it right away, but instead take it back to the dealership and tell them the car is still running bad despite a $300 repair bill. Don't want to let them off the hook that easily by fixing it yourself since enough extra money has already been spent. Best of luck.
 

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I just did a read thru from the start of the post,if you had a maf sensor going bad It might not trip the cel ,,if you had a scan tool you could read the hz frequency ,, the maf reads how much air is coming in and tells the ecm how fuel to add in ,, I would look into the maf sensor
 

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I just did a read thru from the start of the post,if you had a maf sensor going bad It might not trip the cel ,,if you had a scan tool you could read the hz frequency ,, the maf reads how much air is coming in and tells the ecm how fuel to add in ,, I would look into the maf sensor
The issue arose prior to changing the mass airflow sensor and to some degree remained after its replacement. Perchance what brand of mass airflow sensor did you purchase as a replacement?
 

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Discussion Starter #48
I just did a read thru from the start of the post,if you had a maf sensor going bad It might not trip the cel ,,if you had a scan tool you could read the hz frequency ,, the maf reads how much air is coming in and tells the ecm how fuel to add in ,, I would look into the maf sensor
I bought a brand new maf sensor and housing "acdelco", installed that before i decided to take it in to gm dealer. If you watch the youtube video links I posted, it shows my maf readings off my torque pro app and scanner tool
 

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Discussion Starter #49
I just did a read thru from the start of the post,if you had a maf sensor going bad It might not trip the cel ,,if you had a scan tool you could read the hz frequency ,, the maf reads how much air is coming in and tells the ecm how fuel to add in ,, I would look into the maf sensor
The issue arose prior to changing the mass airflow sensor and to some degree remained after its replacement. Perchance what brand of mass airflow sensor did you purchase as a replacement?
It's an acdelco maf and housing brand new
 

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If you've verified the codes are indeed P0171 and P0174 (Lean Codes Bank1/2), and Not P0172/P0174 (Rich Bank 1 Lean Bank 2) like you've stated before, your issue is unmetered air getting into the intake that has not passed through the MAF sensor. Your fuel trims show this. The oxygen sensors are seeing this unmetered air and causing the 02's to dump fuel to compensate. At this point, you should be looking for exhaust and or intake leaks, or even faulted PCV components or hoses.
 

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Discussion Starter #51
If you've verified the codes are indeed P0171 and P0174 (Lean Codes Bank1/2), and Not P0172/P0174 (Rich Bank 1 Lean Bank 2) like you've stated before, your issue is unmetered air getting into the intake that has not passed through the MAF sensor. Your fuel trims show this. The oxygen sensors are seeing this unmetered air and causing the 02's to dump fuel to compensate. At this point, you should be looking for exhaust and or intake leaks, or even faulted PCV components or hoses.
I'm goin to go out there in a little bit and use some throttle body cleaner and spray around the pcv components and hoses while running, if its exhaust leak then it would have to be at the exhaust manifold gasket because the 02 mounts on the header and thats the only place air could get in since its all weld and doesn't have the next connection point till the xpipe
 

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Yes, if it has exhaust leaks, it would most likely be at the manifold gaskets, unless you have a crack or something in the piping. I would focus on intake and or PCV system leaks first because to peg your fuel trims like that, you'd have to have a pretty large exhaust leak you likely could hear. Unless of course you have an obnoxiously loud exhaust.
 

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Discussion Starter #53
Yes, if it has exhaust leaks, it would most likely be at the manifold gaskets, unless you have a crack or something in the piping. I would focus on intake and or PCV system leaks first because to peg your fuel trims like that, you'd have to have a pretty large exhaust leak you likely could hear. Unless of course you have an obnoxiously loud exhaust.
So I just got back in side and I smell like partially burnt fuel from how smelly the exhaust is, anyway I took throttle body cleaner and sprayed around each coupler connection after the maf on the intake and waited after each area I sprayed to see any changes in idle, while also looking at my torque pro app on tablet to see changes. I got noting so went for pcv hoses and connections, again nothing. Pulled pcv connection off driver side rear valve cover and after 3 seconds the motor almost completely cut out and shut off, could hear the air sucking in the nipple. I put it back on quickly and took about 5 seconds or so to get back to normal almost stalling out multiple times. So followed to the purge valve canister thing the pcv hoses go to passenger side next to the throttle body unplugged sensor new code popped up p0444 plugged back in refreshed then went away. Reset cel and bout 2 min cel came on still same codes p0171 p0174.
 

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Discussion Starter #54
Yes, if it has exhaust leaks, it would most likely be at the manifold gaskets, unless you have a crack or something in the piping. I would focus on intake and or PCV system leaks first because to peg your fuel trims like that, you'd have to have a pretty large exhaust leak you likely could hear. Unless of course you have an obnoxiously loud exhaust.
So I just got back in side and I smell like partially burnt fuel from how smelly the exhaust is, anyway I took throttle body cleaner and sprayed around each coupler connection after the maf on the intake and waited after each area I sprayed to see any changes in idle, while also looking at my torque pro app on tablet to see changes. I got noting so went for pcv hoses and connections, again nothing. Pulled pcv connection off driver side rear valve cover and after 3 seconds the motor almost completely cut out and shut off, could hear the air sucking in the nipple. I put it back on quickly and took about 5 seconds or so to get back to normal almost stalling out multiple times. So followed to the purge valve canister thing the pcv hoses go to passenger side next to the throttle body unplugged sensor new code popped up p0444 plugged back in refreshed then went away. Reset cel and bout 2 min cel came on still same codes p0171 p0174.
So I'm taking it in tomorrow back to chevrolet dealership as there closed today. Just can't figure it out. Maybe like I said before could it be a intake manifold o ring gasket I've never taken the intake manifold off the vehicle but that's the last place I can think unmetered air can get in.... I don't know what else to check.
 

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One thing i noticed, after reviewing one of your videos . When you unplugged your MAF the air temp did not change. Your intake air temp sensor is in the MAF. When you unplug the MAF, the intake air temp should have pegged -40°F. Now if there is something wrong with the IAT circuit, it wont necessarily throw a code for it. In some cases, it will just report the wrong temp to the ECM. See if you can locate the IAT reading through your app. It should be close to ambient. I suspect the temp reading that was on your screen was ambient temp reading from some other sensor, possibly for the HVAC controls and NOT the IAT sensor.
 

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Discussion Starter #56
One thing i noticed, after reviewing one of your videos . When you unplugged your MAF the air temp did not change. Your intake air temp sensor is in the MAF. When you unplug the MAF, the intake air temp should have pegged -40°F. Now if there is something wrong with the IAT circuit, it wont necessarily throw a code for it. In some cases, it will just report the wrong temp to the ECM. See if you can locate the IAT reading through your app. It should be close to ambient. I suspect the temp reading that was on your screen was ambient temp reading from some other sensor, possibly for the HVAC controls and NOT the IAT sensor.
Ok I added the iat reading to my track recorder, have to go to work right now driving the malibu as daily, but when I get home today I'll check. Called dealership and they are having me bring it in at 0800 tomorrow.
 

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Discussion Starter #57
So dropped the car off 2 days ago at the chevrolet dealership they are Still working on finding the problem. Obviously they can't figure it out either.
 

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Id be looking into the intake manifold, intake manifold gaskets and any connections to the manifold. Warped or cracked intake would allow a lot more air, post throttle blade, and could get worse with engine temp due to thermal expansion. Would not be the first gm v8 to have intake manifold issues. Ive even seen bolts loose on plastic manifolds, never touched

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Discussion Starter #59
Id be looking into the intake manifold, intake manifold gaskets and any connections to the manifold. Warped or cracked intake would allow a lot more air, post throttle blade, and could get worse with engine temp due to thermal expansion. Would not be the first gm v8 to have intake manifold issues. Ive even seen bolts loose on plastic manifolds, never touched

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Yeah I told them electrical or possible leak on intake manifold, so hopefully they check or already checked.
 

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So dropped the car off 2 days ago at the chevrolet dealership they are Still working on finding the problem. Obviously they can't figure it out either.
Make sure they are actively and actually working on the vehicle so it isn't sitting in a bay or stall collecting shop dust.
 
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