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Author
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Topic: low power loss/oil on spark plug
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dean-93
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Member # 9401
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posted
 
 
we have be trying to fix this problem for months on a friends car
at idle it runs good but when u drive it it sputters and runs rough and not enough power
i did a compression test today and they were all 150/145psi but the number 7 spark plug was oily/black all others were really white
ive checked and replaced all the vac hoses
swaped every sensor from my working car
timing is 12 degrees
new plugs wires
new distributor and tfi (motorcraft)
swaped coil with mine
o2 have been changed
fixed exhaust leak
zero intake leaks
swaped mafs
new fp regulator
weve done everything, im thinking the car is goin lean a throttle,i checked fuel pressure its 40psi at idle we didnt check it while driving tho
any ideas?
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93 5.0 trickflow h/c/i
Posts: 1175 | From: novato and fairfeild | Registered: Aug 2009
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dean-93
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Member # 9401
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posted
its a 93 gt with headers h pipe and flows thats it
it also over heats quick so maby a good chance its goin lean,i got a new fuel pump for it and were gunna swap it tonight
btw i also swaped in my old working injectors too no change
NO CODES!!!
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93 5.0 trickflow h/c/i
Posts: 1175 | From: novato and fairfeild | Registered: Aug 2009
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Grants93GT
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Member # 10614
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posted
White plugs would say it is running lean, and the over heating sounds about right too. It definitely sounds like a fuel issue, as in it is not getting enough. Do you ever hear it pinging? Maybe, if you haven't already checked, it could possibly be the ecu itself? Maybe if you swapped that over with another working one, it might be the problem. That seems like the only thing you haven't checked. Maybe a clogged fuel filter, something restricting fuel from getting correct flow.
Posts: 208 | From: Central Valley | Registered: Jan 2011
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dohc90lx
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Member # 11863
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posted
run a cylynder leakdown test on number 7. common problem also is cross fire thrugh the spark pulg wires that results over time in a burnt piston from cross arcing. causing oil on one plug. there will be a spot on the cylyder wall as well that had piston material spattered onto it. usually pretty far down the wall causing a compression test to pass but a leakdown to fail. key to this is to remove the rockers off that cylynder hook up your leak tester then slowly roll the engine around so the piston moves down the bore untill the bottom. or use a borescope and check it. its not too common but deffenetly seen it before. its more common in trucks and broncos with the other firing order. but thats because cylynders 7 and 8 fire right next to eachother.
Posts: 129 | From: antioch | Registered: Apr 2012
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dohc90lx
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Member # 11863
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posted
check your grounds for the rough run too. a loose ground will do some strange things.
Posts: 129 | From: antioch | Registered: Apr 2012
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