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detonation last night!!??

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Old 10-31-09, 08:10 AM
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TX detonation last night!!??

so last night long story short i was gonna give bro a ride from his friends house...so i'm turning out from my neighborhood and caught the light, i barely did iand wen i take that sharp turn i usually jst slide the tail a little bit jst to have fun and feel it. well it had no traction threw 1st gear so i shifted into second, 'boosting like 8' and wen it gripped into second, the car suddenly shuts off OUT OF THE BLUE!! its never happened before so i was confused and i know my car verry well..looked under the hood and apparently the AFM plug came off the AFM while i was boosting...it happened last night and i was thinking that while in boost and the AFM comes unplugged it would LEAN the HELL outa my car cause detonation.. huh? after that it ran like the whole engine was unbalanced and no power wut so ever..i'm more then sure the motor blew but my question is...was the cause-'the AFM unplugging while in boost'? cause that sounds reasonable..thanks guys.
Old 10-31-09, 08:18 AM
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ur afm might be no good, my car ran like **** one night after the track, i thought 4 sure my motor was shot, it turned out to be the afm...after that Haltech & i became best friends
Old 10-31-09, 08:49 AM
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I would be reasonably certain that if the AFM came unplugged it just shut down the fuel pump.,.
Old 10-31-09, 08:53 AM
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Originally Posted by J-Rat
I would be reasonably certain that if the AFM came unplugged it just shut down the fuel pump.,.
thanks for yalls input guys!
yeah thats wut i was thinking, but if the fuel pump goes off Automatically in boost, it wouldnt blow the motor? i was thinking that would make it run lean to the MAX until it turned off...:/
Old 10-31-09, 08:55 AM
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Originally Posted by 1nastyturboII
ur afm might be no good, my car ran like **** one night after the track, i thought 4 sure my motor was shot, it turned out to be the afm...after that Haltech & i became best friends
haha yeah! haltech is wonders! wayyy outa my price ranger for now though! :/
Old 10-31-09, 10:24 AM
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front rotor is blown guys..have no idea why..the only thing i noticed was wen i boosted and got out the car on the side of the rode, i saw the AFM plug un-hooked..idk if that has anything to do with it blowing but thats why it wasnt staying on..wen i plugged it in, it barely ran and idled..but as i said, as if i had no counter weight on the dam engine..
'unbalanced' shaky as ****. :/ thanks guys for the feedback though.
Old 10-31-09, 10:32 AM
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Engine, Not Motor

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No idea why?! If the AFM unplugged itself under boost, the fuel pump shuts off and injector duty drops to some very low level and then to zero.
Old 10-31-09, 11:00 AM
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Originally Posted by Aaron Cake
No idea why?! If the AFM unplugged itself under boost, the fuel pump shuts off and injector duty drops to some very low level and then to zero.
so then my 'thoughts' when i saw the AFM unplugged was right huh!?
thanks aaron for clearing it up. thats wut i was thinking! :/
suks...thanks guys..
Old 10-31-09, 04:54 PM
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Originally Posted by rex7tuner
thanks for yalls input guys!
yeah thats wut i was thinking, but if the fuel pump goes off Automatically in boost, it wouldnt blow the motor? i was thinking that would make it run lean to the MAX until it turned off...:/
Ya, a little lean is dangerous, but no fuel at all = no boom. If it is blown then it should fail a compression test. If it's just not running then it could be the AFM or anything.
Old 10-31-09, 05:13 PM
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The stock fuel cut setup completely switches the rear injectors off under boost, but it shouldn't lead to blown engines. No fuel at all means no combustion. I take it a compression test was done to decide the front rotor blew? What were the numbers?
Old 10-31-09, 06:36 PM
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The stock fuel cut setup completely switches the rear injectors off under boost, but it shouldn't lead to blown engines.
ahh but an unplugged AFM is not the same as overboost fuel cut. It will disengage the circuit opening relay, resulting in a disengaged fuel pump and a loss of fuel pressure. That will lead to a lean condition while the engine is still running. It's not a sudden and hard cut. And who knows what happened to the ignition timing when that plug came off.

Next time... install the plug retaining clip.
Old 10-31-09, 07:21 PM
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True enough. The injectors could still fire momentarily with dramatically lowered fuel pressure.
Old 10-31-09, 11:44 PM
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Originally Posted by arghx
ahh but an unplugged AFM is not the same as overboost fuel cut. It will disengage the circuit opening relay, resulting in a disengaged fuel pump and a loss of fuel pressure. That will lead to a lean condition while the engine is still running. It's not a sudden and hard cut. And who knows what happened to the ignition timing when that plug came off.

Next time... install the plug retaining clip.
yeah.thanks for the input guys..
i new i should have found another dam clip! :/
Old 11-01-09, 10:44 AM
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Engine, Not Motor

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An unplugged AFM plug is going to be intermittent moments before it unplugs, so you can expect lean/rich spots and not just a nice clean fuel cut.
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