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Discussion Starter #1
Hello,

My 2009 G8 GT recently started acting up. It has 85k miles , custom tune, headers and CAI. All the work was done 3 years ago. Recently the car has been running great and one day wouldn’t start. It would turn over but not start. Now the car will run fine for about a minute then start to sputter and then stall and die. I’ve replaced the fuel pump,MAF,throttle body, cam shaft position sensor, and the Crank shaft position sensor. There are no check engine lights. Once the car dies it doesn’t turn back on unless the throttle is open. If I give the car gas it will stay running but you can feel as if it’s misfiring. Once the gas is let off it will stall. Any input would be greatly appreciated.

Thank you,
 

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I'm not familiar with the approximate values that are dialed in when you have one of the several tunes available. In my car (which is stock) with engineering mode selected an the engine off, the throttle body blade position reads 22%. After engine start, my idle shows a blade angle of about 7%. Thinking that those engines that have added some level of tune to it, that idle blade setting probably is a little higher. There sure has been several members who have had a tune in their cars for some time, an things start to go bad out of nowhere. I want to say after they start a thread, followup posts from others, suggested that they take their tunes back to stock to see what happens. Thinking that a lot of them had their existing problems go way down or possibly eliminated. Could it be that your engine has fallen into this situation ?

Then again, those that have tunes an post a reply, might know exactly what has happened here.
 

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Yeah I keep thinking it’s a fuel problem. I contacted my tuner he stated I need to change the plugs and wires & ensure the MAF is clean. The plugs and wires have less than 20k miles and well I have a new MAF lol. Also he lives about 3 hours away from me and there’s no way to get the car down there without hiring a tow truck.
 

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Three questions. What brand(s) are the replacement parts? Does the obd II scanner read pending check engine codes? Have the fuses and relays been checked for proper operation? If you have roadside assistance, it may be able to help if the car needs to be towed to the tuner. At the very least, could be a fuel delivery issue.
 

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Discussion Starter #5
All parts have been OEM acdelco and Delphi . I’ve checked all fuses and relays. Pulled each one out ensures it was good and placed back.
 
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