raidermaniac

i have a 2005 civic sedan dx,today i was going to replace my exhaust manifold,i unplugged one oxygen sensor to remove the heat shield and discovered the three nuts under the shield holding the manifold to the head were so rusted i couldn't get them off..so decided to put shield back on and work on this another day.i plugged the sensor back in and when i started the car it was idling really rough and misfiring,and when i would press the gas pedal it would almost die...so i tried disconnecting the battery cable for about a half hour and then restarted the car and let it idle for about 10 minutes it still ran rough and didn't get any better..i turned car off let it sit awhile and tried again with same results..the last time i turned it off and tried to restart it,it wouldn't start now it just turns over but won't start but i can smell strong gas smell from engine.the car ran fine with no problems before i attempted to change the manifold and the only thing i unplugged was the sensor,anyone have any ideas what's going on with this?

ezone

I can't see (yet) how JUST unplugging the sensors would cause problems.
The sensors aren't even used until they are hot and active.
Disconnecting them should put the computer in failsafe (base fuel) map.

Was anything else done at that time?
Maybe something entirely different and unrelated just happened to become a new problem?

Maybe it's just flooded from a few short starts and not running long enough to get fully warmed up.

raidermaniac

i cant understand how just unplugging the sensor would cause this problem either so i'm thinking it must be something else,but why all of a sudden with not even a hint of problems before this? the car did idle long enough to completely warm up a few times before refusing to start again...i'm now thinking maybe a cam or crank shaft sensor

ezone

Ah! Too much idling might cause it.

Idle alone doesn't get the spark plugs hot enough to clean the carbon off of them, whereas "spirited" driving gets the plugs much hotter.

But do not run it or drive it if it has a dead miss, you can trash the cat.

Read the codes, see what it has in there. Don't guess and throw parts at it.
If it's missing, that check engine light should have been angrily flashing.

Pull the spark plugs out and see if any are black/wet.
See if you might have a dead coil, or diagnose why it's missing. Or whatever it's doing.

Does it just have a dead hole? Does it only miss at idle, or is it totally dead even at higher rpm?


HTH

raidermaniac

well i definitely couldn't do any spirited driving the way it was so i let it idle,i was pretty sure it wasn't just flooded....anyway checked the timing belt it had loss some teeth and was out of time...long story short bent valves and apparently just a conincidence that it happened just after trying to replace the exhaust manifold.