Help!!! I need a 550 guru!!! Misfiring

Not sure what you mean by ".....we found bank one said closed and bank two said disabled."

Could you explain a little more, or provide the actual codes that were found?

 

Did you check the fuel filters for rubber from the pump surrounds in the tank? Fuel problems often masquerade as ignition problems.

 

OK, this may sound like a silly question, but how do you know you have a misfire, ie what exactly is the car doing? Running rough, or something else?

Did you change the plug wires & coilpacks yourself, or did a pro do it?

And just to clarify and make sure we're on the same page, did you change the plugs, plug wires and coilpacks BECAUSE you had a misfire, or did the misfire appear after you did this work?

 

The first thing we check on a misfiring Maranello is the intake plenum gaskets. The smallest leak causes the car to freak out. Start by smoke testing the intake plenum then move onto the fuel system. Normally I see them leak at plenum to head connection. Ferrari came out with a metallic gasket to resolve this issue. Post your codes also.

 

I had my techs torque the intake manifold every annual service for 5 years, but when they did the 10 year with degreeing of the cams, the intake manifold gaskets were completely shot. Like Dan said, the new ones are metal with a rubber/nylon surround, so should work much better at the low torques of the fasteners.

 

Sorry I just reread your post. When the did the plugs did the pull the side plenum covers? If so I would say 100% thats where your leak is. I screwed up a few times installing the side cover gaskets with the plenum on the car before and had similar issues. The gaskets drop sometimes and you end up putting the bolt in with the gaskets pushed out under it creating a leak.

Taking a few miles makes sense since the MAF needs time to pickup on the leak when comparing against the o2 readings.

 

Good advise. Anyone doing annuals have your tech check the plenum hardware tq and while your at it exhaust manifolds bolts. For some reason I always find maranellos walk the exhaust nuts off the manifold studs.

 

Did you try locating where exactly the misfire is occurring? (which cylinder)?

Did you check the lead cables? - I remember some on here having issues with them and getting damaged.

Spray WD-40 or brake cleaner around the intake plenum to see if it makes a difference -but if the leak is happening on the underbelly of the plenum, it will not be easy to detect.

 

You need to determine if the misfire is spark or fuel related - first locate where exactly the misfire is, then you can start swapping out fuel injectors, ignition cables and so on.

 

OP description is not clear to me. OBD2 and EOBD are very sensitive and can pick out very mild undetectable misfire and will show up as misfire hard code p0300 series.

 

Yeah the first step should have been a smoke test IMO before jumping on the ignition setup. Give it a shot and let us know how you make out. If you come up short on the plenum leak we can figure out the next logical step. If they find the leak order the following parts to really make sure you covered everything.

2 x 225462
2 x 154562
2 x 142934
24 x 159601
24 x 133902

If you end up pulling the plenum check all the vac hoses ends for dry rot and see if the center valley coolant hoses have been upgraded to 575 style. Feel free to have your tech give me a ring at the shop if he wants to bounce ideas.

 

I agree. Normally you will find random multiple misfire codes. See if you have any codes pending they might not be solid codes yet.

 

If the problem starts after the engine warms up, I would check the intake plenum before anything else.