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Join Date: May 2002
Location: Up North
Posts: 1,449
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Loud backfire POP when shut down?
Whenever I shut down the car, I get a LOUD explosion pop right from inside the muffler (a custom "non-blocking" i.e. I can see thru it from 1 end to the other).
Any suggestion on what can I do to get rid of that? (For background - my idle AFR is around 14.8 so she's not running rich there). thanks...
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87 930 K27HFS/B&B/Twin-Plug... Megasquirted 
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08-19-2008, 12:30 PM
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Slantnose from HELL
Join Date: Dec 2004
Posts: 888
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possibly a wasted spark discharging a spark on a cylinder when the exhaust valve open igniting the unspent gasses in the exhaust?
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08-19-2008, 12:35 PM
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umm... you could be right! But if that's the case, then it means there's nothing I can do to stop that then?
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87 930 K27HFS/B&B/Twin-Plug... Megasquirted
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08-19-2008, 12:47 PM
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Slantnose from HELL
Join Date: Dec 2004
Posts: 888
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Are you twinplug and what coils are you running?
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It changes from time to time..... Last edited by GJF; 08-19-2008 at 12:55 PM.. Reason: spelling |
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08-19-2008, 12:55 PM
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Yes, I'm twin plug; wasted spark. Coils are Mitsubishi ones (for 3000GT).
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87 930 K27HFS/B&B/Twin-Plug... Megasquirted
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08-19-2008, 01:02 PM
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Slantnose from HELL
Join Date: Dec 2004
Posts: 888
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Are you firing the coils to these respected cylinders?
coil A 1&4 coil B 3&6 coil C 2&5 And the same for the second set of coils?
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08-19-2008, 01:23 PM
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Registered
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Quote:
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87 930 K27HFS/B&B/Twin-Plug... Megasquirted
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08-19-2008, 04:12 PM
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Slantnose from HELL
Join Date: Dec 2004
Posts: 888
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What are your timing values from idle to 0" of vacuum? (Or 101kPa) Or let's see your timing map. Not sure but maybe too advanced from idle to 0"?
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08-19-2008, 04:43 PM
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Registered
Join Date: May 2002
Location: Up North
Posts: 1,449
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Going from memory, my idle timing is around 8 deg.
I don't think other timing could cause this as I'm nowhere near off-idle vacuum?
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87 930 K27HFS/B&B/Twin-Plug... Megasquirted
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08-19-2008, 06:10 PM
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