My valve cover on the passenger side leaks quit a bit (ever since I bought it). I have replaced O2 sensors (all four), paper air filter, Magnecor 8mm with Bosch +2, new MAF, new purge valve, and replaced all the PCV hoses/oil seperator. The engine runs strong but continues to throw the 1171/1174 codes (LH/RH bank additive trim injector rich limited exceeded).

My question is whether my very leaky valve cover could be causing a huge vacuum leak and causing the engine to add more fuel to compensate (rich injector trim exceeded)? My PCV system has slowly become louder and louder with a whistling noise closed throttle driving or at idle. It is enough of a problem that I can't ignore.

Cheers,

Pete

 

I read this concerning vacuum leaks and fuel trim:

"Vacuum leaks will typically cause the fuel trim to run rich as the computer tries to compensate for the extra air being sucked into the engine through the leak."

-http://www.aa1car.com/library/problem_hesitation.htm

Cheers,

Pete

 

A leaking valve cover will only leak oil, all the vacuum comes from the intake plenum, so unless you have a leaking intake plenum or something that attaches and runs off the intake vacuum, like a brake booster line, cruise control, PCV hose etc.
Tighten your leaking valve covers with a 1/4" drive 12 point 8mm socket, snug them up.
Fix your leaking PCV hose and go from there.

Vacuum is made by the engine sucking in the air it needs, nothing else on/in the engine will create vacuum.

 

PCV system is not leaking. It sucks air from the crankcase via the passenger valve cover which is leaking. I'm thinking it is so loose it is sucking in air from between the head and the valve cover creating a vacuum leak. I'm going to tighten down the cover and see what happens. A smoke machine is my last resort.

Cheers,

Pete

 

Ok, I mis understood your first post, if the valve cover is that loose then your truck should have caught on fire by now as all the oil would be leaking onto the exhaust manifold.

 

Tighten your valve cover, power scrub your engine and send me your tele number.

 

Turns out it was worn out pulleys. New ones on the way.

I am still getting the 1171/1174 codes. I'm going searching for a vacuum leak this weekend. The engine runs really well except for the codes and occasional rough idle (when I get the codes).

Cheers,

Pete

 

Clogged Cats?

 

It's possible. I had a severe misfire from bad spark plug wires and it could have damaged the cats. If that is the case I'm going to just live with it. New cats are a tad too expensive for this old Rover.

Cheers,

Pete

 

I think you should have an overall engine inspection. Get a local mechanic to have it checked. With that, you can also ask for assistance for the replacement of your Valve Covers.