[si2t3m]

Hi,

#3 cylinder is acting up. The cylinder is dead at idle but wakes up on acceleration. At constant rpm say at highway speed, i can feel the car jerking like #3 coming on and off. At contant rpm (lower rpm) cylinder is dead. Don't worry i don't drive the car around like this. I'm only troubleshooting!

Engine is a 3.0L with Webers. All this started when i lauched pretty hard (might overreved the engine as i have no rev limiter). Car was low on gas also.

I checked the cap and distributor and they are ok.
I have spark. I changed the plugs and it's still the same.

Fuel pressure gauge located just before the carbs shows 3psi.
Had crud in one of the fuel filters located before the fuel pump. I replaced it. Still the same.

I checked the compression and it was even on all cylinders. I'm I ok to say that I can rule out a bent valve (from a possible overrev) if compression is good and syncrometer hows that it's drawing the same amout of air as the others???

I checked the idle jet and main jets. Took the carb apart and checked for blockage in the idle circuit. none.

Checked with a propane around the base of the carbs. No implovement.

Inspected the manifolds for cracks. Nothing.

It didn't suck a gasket either.

I gotta confess that i'm clueless on what is going on.

I'm seeking for ideas!

What could cause #3 to be dead at idle, and pick up on acceleration and be intermitant at constant rpm (in the 3000-4000 rang)???

Marc-André

TIA

Marc-André