Backfire through intake when key is turned to on?
05-11-2017, 08:20 PM
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Backfire through intake when key is turned to on? E38 engine management LS2 E38 engine Mgmt Harness
4L6XE LS2 4L60E/4L65E Trans
Pedal (Not needed but on original invoice)
When idling, the vehicle runs extremely rich. After shut down and several hours later, when the key it turned to the 'on' position, not 'crank' a very bid backfire occurs through the intake. To the point of blowing vacuum lines and fittings apart. Obviously, the fuel for this backfire is left over from the super rich mixture, but why the spark when key is turned to the on position?
4L6XE LS2 4L60E/4L65E Trans
Pedal (Not needed but on original invoice)
When idling, the vehicle runs extremely rich. After shut down and several hours later, when the key it turned to the 'on' position, not 'crank' a very bid backfire occurs through the intake. To the point of blowing vacuum lines and fittings apart. Obviously, the fuel for this backfire is left over from the super rich mixture, but why the spark when key is turned to the on position?
09-12-2019, 11:59 AM
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E38 engine management LS2 E38 engine Mgmt Harness
4L6XE LS2 4L60E/4L65E Trans
Pedal (Not needed but on original invoice)
When idling, the vehicle runs extremely rich. After shut down and several hours later, when the key it turned to the 'on' position, not 'crank' a very bid backfire occurs through the intake. To the point of blowing vacuum lines and fittings apart. Obviously, the fuel for this backfire is left over from the super rich mixture, but why the spark when key is turned to the on position?
4L6XE LS2 4L60E/4L65E Trans
Pedal (Not needed but on original invoice)
When idling, the vehicle runs extremely rich. After shut down and several hours later, when the key it turned to the 'on' position, not 'crank' a very bid backfire occurs through the intake. To the point of blowing vacuum lines and fittings apart. Obviously, the fuel for this backfire is left over from the super rich mixture, but why the spark when key is turned to the on position?
03-21-2023, 12:08 PM
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Anyone find a reason for this?
11-09-2023, 05:01 PM
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I was reading through older posts today and came across this discussion. Before I comment I would like to confirm a few things.
All people experiencing this happen have an actual ignition key that rotates to engage the starter. In other words, no push button start.
The backfire occurs when the key is rotated, before the starter engages - no crankshaft rotation.
I was quite surprised to read this because I worked on resolving an issue like this 33 years ago while working for GM.
I assumed it would have been corrected from that point on.
All people experiencing this happen have an actual ignition key that rotates to engage the starter. In other words, no push button start.
The backfire occurs when the key is rotated, before the starter engages - no crankshaft rotation.
I was quite surprised to read this because I worked on resolving an issue like this 33 years ago while working for GM.
I assumed it would have been corrected from that point on.