Engine misfire HELP wanted!
Thread Starter
Burning Brakes
Joined: Jun 2004
Posts: 1,186
Likes: 21
From: West Tennessee
Engine misfire HELP wanted!
Base motor, completely stock. Idles fine, accelerates fine, but when at cruise, (2800rpm) you can feel/hear a slight stumble/misfire. I have checked for obvious issues and found none. Do you think this may be more fuel/carb related opposed to ignition? What puzzles me is that at idle/acceleration, no matter how much, it runs great. Just cruising at 65mph and sometimes when slowing from that speed it develops this miss fire or stumble.
Ideals?
Ideals?
Drifting
Joined: Sep 2004
Posts: 1,959
Likes: 1
From: North Bend Ohio
First of all, what year is this car? If it's a smog car check the vacuum hoses and the EGR (exhaust gas recirculation) system. A vacuum leak in a ported vacuum hose could cause this. Take a look at the TCS (transmission controlled spark) for possible vacuum leaks.
I'm thinking that this is a vacuum leak in the part throttle/cruise portion of the induction system. If there is a leak in a ported vacuum hose it would not show up at idle and the extra enrichment during acceleration may be covering up for it. The only time you would feel it is when the carburetor leans out at cruising speeds. This is called a lean surge.
BigBlockk
Later.....
I'm thinking that this is a vacuum leak in the part throttle/cruise portion of the induction system. If there is a leak in a ported vacuum hose it would not show up at idle and the extra enrichment during acceleration may be covering up for it. The only time you would feel it is when the carburetor leans out at cruising speeds. This is called a lean surge.
BigBlockk
Later.....
Thread Starter
Burning Brakes
Joined: Jun 2004
Posts: 1,186
Likes: 21
From: West Tennessee
Thanks for the tips guys. The car is a 72. I will go after the vac system and also check the advance. Is there any specific gauge activity I should look for on the manifold vac when the motor is at cruise/lean condition?
