Spark Plug Backing Out?
Thread Starter
Le Mans Master
Joined: Mar 2013
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From: Ahead of You :)
St. Jude Donor '14
Spark Plug Backing Out?
As topic states what causes this and what kind of symptoms would you get?
What would cause this to happen? How do you prevent it from happening again?
I'm having an issue on my boosted car and I'm a little leery about the explanation for the proposed problem. Basically no check engine lights or anything but after a long drive in hot weather car falls on it's face over 4000rpms. Let it sit and cool for an hour and I can get one somewhat good hit out of the car and then it falls flat on it's face again. Car now is on methanol so it's not the hot air intake temps but the hot weather in general seems to be causing a problem elsewhere. Remedy, stop driving for the day and start driving the car again tomorrow it's back to normal.
I had this happen once before and we replaced plugs/wires and that seemed to have remedied the problem. I loose boost when this happens (likely from the lack of power the engine is putting out).
What would cause this to happen? How do you prevent it from happening again?
I'm having an issue on my boosted car and I'm a little leery about the explanation for the proposed problem. Basically no check engine lights or anything but after a long drive in hot weather car falls on it's face over 4000rpms. Let it sit and cool for an hour and I can get one somewhat good hit out of the car and then it falls flat on it's face again. Car now is on methanol so it's not the hot air intake temps but the hot weather in general seems to be causing a problem elsewhere. Remedy, stop driving for the day and start driving the car again tomorrow it's back to normal.
I had this happen once before and we replaced plugs/wires and that seemed to have remedied the problem. I loose boost when this happens (likely from the lack of power the engine is putting out).
Team Owner
Joined: Aug 2006
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C6 of Year Finalist (appearance mods) 2019
Might have a stripped head. Someone might have put plug in a hot/warm engine and over tightened the plug.
Had a plug blow out of my supercharged Lightning truck.......needed a new head.
GL
Had a plug blow out of my supercharged Lightning truck.......needed a new head.
GL
Race Director
Joined: Dec 2013
Posts: 12,505
Likes: 3,632
Either a stripped head channel, or heat soak and the boost pressure.
Hence, fuel is cooling, so with boost, always run on the richer AFR side!!!
Also, meth is not being run full time, so you can't count on it to keep the engine cool full time (being used to prevent detonation with advance ignition timing during boost instead).
Hence, fuel is cooling, so with boost, always run on the richer AFR side!!!
Also, meth is not being run full time, so you can't count on it to keep the engine cool full time (being used to prevent detonation with advance ignition timing during boost instead).
Thread Starter
Le Mans Master
Joined: Mar 2013
Posts: 7,390
Likes: 137
From: Ahead of You :)
St. Jude Donor '14
Either a stripped head channel, or heat soak and the boost pressure.
Hence, fuel is cooling, so with boost, always run on the richer AFR side!!!
Also, meth is not being run full time, so you can't count on it to keep the engine cool full time (being used to prevent detonation with advance ignition timing during boost instead).
Hence, fuel is cooling, so with boost, always run on the richer AFR side!!!
Also, meth is not being run full time, so you can't count on it to keep the engine cool full time (being used to prevent detonation with advance ignition timing during boost instead).
Race Director
Joined: Dec 2013
Posts: 12,505
Likes: 3,632
Check your AFR at mid and low throttle, and might want to think about putting a small timed delay to ramp down the meth spray when you come off the throttle, instead of it just shutting off; to help cool the heat soak heads down after you come off boost.
The heads have no water channel cooling, and you have a steel spark plug in an aluminum head (two different heating and cooling rates), plus the Meth is only kicking in during boost.
So the head spark plug channels are expanding the hotter the heat soak is, and this, combined with the boost pressure may be just enough for start backing out the plugs when the heads get heat soaked (the 11ftlbs of spark plug torque only, is not helping the cause either).
The heads have no water channel cooling, and you have a steel spark plug in an aluminum head (two different heating and cooling rates), plus the Meth is only kicking in during boost.
So the head spark plug channels are expanding the hotter the heat soak is, and this, combined with the boost pressure may be just enough for start backing out the plugs when the heads get heat soaked (the 11ftlbs of spark plug torque only, is not helping the cause either).
Thread Starter
Le Mans Master
Joined: Mar 2013
Posts: 7,390
Likes: 137
From: Ahead of You :)
St. Jude Donor '14
Check your AFR at mid and low throttle, and might want to think about putting a small timed delay to ramp down the meth spray when you come off the throttle, instead of it just shutting off; to help cool the heat soak heads down after you come off boost.
The heads have no water channel cooling, and you have a steel spark plug in an aluminum head (two different heating and cooling rates), plus the Meth is only kicking in during boost.
So the head spark plug channels are expanding the hotter the heat soak is, and this, combined with the boost pressure may be just enough for start backing out the plugs when the heads get heat soaked (the 11ftlbs of spark plug torque only, is not helping the cause either).
The heads have no water channel cooling, and you have a steel spark plug in an aluminum head (two different heating and cooling rates), plus the Meth is only kicking in during boost.
So the head spark plug channels are expanding the hotter the heat soak is, and this, combined with the boost pressure may be just enough for start backing out the plugs when the heads get heat soaked (the 11ftlbs of spark plug torque only, is not helping the cause either).
