Any idea on whats wrong??

Billitt_69 · Dec 16, 2010

Just looking for a place to start..
Have a 99 Gt with a Procharger.
It smokes out the tailpipes at idle, when under excelleration it smokes pretty bad.. Sounds as if the motor has a knock. Purchased the car this way for extremely cheap amount. so i'm just looking for a place to start.. would it be better to tear this motor apart? or find another motor to install..

the motor sets of the check engine light makes it blink.. assuming that means a misfire? also looks as if a piston is slapping on a plug in one of the cylinders... so any idea?

baggett3_27 · Dec 16, 2010

compression test for starters

GDawg · Dec 17, 2010

What color smoke? Does it smoke during decelleration?

Coyote5.0 · Dec 17, 2010

The blinking check engine light means a misfire (and usually a pretty bad one).

Does it burn oil? Does it knock all the time, or just under a load? Also, what makes you think a piston is hitting a spark plug?

trinity_gt · Dec 17, 2010

It sounds like the engine is hurt: smoking, knocking and misfires on a blown motor -- presumably with a stock bottom end -- pretty much assures that. My guess is that a piston has been damaged by detonation.

If the Procharger setup is responsible for the damage -- too much boost or a fault such as, say, too little fuel -- then address that. If the boost is set for 10 psi or less and you're intercooled, it's probably better to search wrecking yards for a replacement stock shortblock (or complete engine) than to try to repair your existing engine. If the blower setup is more aggressive then replacing the engine with another stocker will likely lead to the same problem. In that event, you might want to dig into the engine you've got and upgrade the rods and pistons, assuming the rest of it is not beyond repair (e.g. cylinder bore damage...)

Billitt_69 · Dec 17, 2010

Coyote5.0 said:
The blinking check engine light means a misfire (and usually a pretty bad one).

Does it burn oil? Does it knock all the time, or just under a load? Also, what makes you think a piston is hitting a spark plug?

burns oil.. doesnt knock all the time... and i think its hittin a plug because when i pull the plug out the plug is bent inwards touching the spot where it would spark

Billitt_69 · Dec 17, 2010

trinity_gt said:
It sounds like the engine is hurt: smoking, knocking and misfires on a blown motor -- presumably with a stock bottom end -- pretty much assures that. My guess is that a piston has been damaged by detonation.

If the Procharger setup is responsible for the damage -- too much boost or a fault such as, say, too little fuel -- then address that. If the boost is set for 10 psi or less and you're intercooled, it's probably better to search wrecking yards for a replacement stock shortblock (or complete engine) than to try to repair your existing engine. If the blower setup is more aggressive then replacing the engine with another stocker will likely lead to the same problem. In that event, you might want to dig into the engine you've got and upgrade the rods and pistons, assuming the rest of it is not beyond repair (e.g. cylinder bore damage...)

Yes it's supposed to be set at 10 pounds.. or thats what the guy said i purchased it from.. have not really messed with it awhole lot.. when i plug the tester in it says that its running rich and fuel and has a mis fire.. i replaced the coil and the plug on the cylinder and it still misfires.. im in the process of tryin to find another decent motor at a salvage yard.. or maybe another member on here..

trinity_gt · Dec 17, 2010

Billitt_69 said:
Yes it's supposed to be set at 10 pounds.. or thats what the guy said i purchased it from.. have not really messed with it awhole lot.. when i plug the tester in it says that its running rich and fuel and has a mis fire.. i replaced the coil and the plug on the cylinder and it still misfires.. im in the process of tryin to find another decent motor at a salvage yard.. or maybe another member on here..

There may be debris in the cylinder bouncing around that's causing the knock and pounding the plug gap closed.

If a piston has been damaged by detonation, a piece of it above the top ring land can snap off. It's possible that the metal hasn't embedded itself into the piston or head yet and is what's closing the plug gap.

nfsug2cobra · Dec 20, 2010

Your bent spark plug throws up big flags for detonation. It can do some pretty freaky stuff. Seen pistons with worm tracks on them. Plugs that looked like they had been hit with a hammer. Motor is toast. It's easy enough to find good cores in the yards. Walk through the forum for upgrades for a forged block. Keep it under 10 pounds of boost. Anymore is really unusable on the street. Keep the heat range down on the plugs. Keep it a little rich, and watch the timing or you will be doing this again.

SiahNyde · Dec 20, 2010

I just finished a full rebuild on my procharged 99 gt. got a serious engine sound and it turned out to be a spun rod bearing. build was a a serious task and took about 9 months...was alot of fun but i'd recomend either paying labor or preparing to become a 4.6l sohc expert during the rebuild! I built my '99 into a 17 pound, 473 horse beast and have alot of performance and OEM parts left over! if you need anything in particular, i'd be glad to help!

Any idea on whats wrong??

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