I recently bought a 1996 Volvo 850 Turbo. It seems to be running rich. I can smell it at idle and there is a little smoke from the exhaust at idle. I pulled the plugs and all had black soot on them. There are no codes and the check engine light is not on. It seems to run ok while driving and no smoke while driving that I can see.

What can cause it to run rich when there are no codes?

 

Goooooooogle.

02 sensors, fuel pump, replace the spark plugs (especially if they look the way you described them), air filter, MAF, FPR, etc etc etc. Just because your not getting a CEL doesn't mean something's not broken.

And what color smoke are you getting at idle? Black smoke is unburnt fuel, if it's anything other than that, then the smoke at idle isn't your running rich problem.

 

What gilber said...

+..

is your CEL working? Assuming yes, first thing i would ck is fuel pressure. Supposed to be around 42/43 psi at idle. Maybe the PO blocked the vac line to it? Just guessing at this point. Fuel pressure being out of whack won't set a CEL (typically).

 

It looks like black smoke at idle. I changed the plugs and air filter and there was no change. I have ordered new O2 sensors. I tried to check the fuel pressure regulator but can't get to it since it is mounted under the intake manifold. Someone suggested disconnecting the vacuum line to see if it has fuel in it which would indicate it has failed. I have a fuel pressure tester and will hook it up and see what the pressure is. Would higher than normal fuel pressure cause it to run rich?

 

I am new to this forum and getting a thread started seems to be a mystery.....so here it goes, I have water coming into the car from the a/c unit and it is quite a bit and I am concerned for all the wires underneath the area where there seems to be some kind of breach. Even when the a/c isn't running there is still quite a bit of water(fresh,not antifreeze)......HELP!!!!!!