I just got a 2000 xj8. It had a miss and check engine light on with power reduce comes on at times. Guy I got it from replaced the plugs but the 2 cylinder back on drivers side do to striped bolt. I got bolt out and changed that plug. I got codes pulled some I have no info on. Any help is appreciated
P0171 bank 1 lean
P0174 bank 2 lean
P0300 random misfire
P0303 cylinder 3 misfire
P0307 cy 7 misfire
P0308 cy 8 misfire
P1316
P1642
P1111
P1000

 

Sounds like you have a large induction air leak. I would check the inlet pipe, connection to air filter, condition of seal between pipe and throttle body, condition of large breather hose and small breather on drivers side.

 

I just sprayed all the induction hoses down with starting fluid and no RPM change so going to say there all good. They all look good too. I sprayed all around TB with no RPM change

 

I had the lean codes with a vacuum leak due to the part load breather hose being broken. But, I have seen a few posts where the harmonics tube, or whatever it's called, was cracked and leaking. The little nub of plastic that is sticking out of the intake pipe between the throttle body and the MAF. Just a thought.

 

I sprayed All the vacuum lines and the whole intake down I can't find any leak

 

I cleared the codes and drove it. After 40 miles I checked codes again an got
P0174
P0300
P0302
P1316

 

I had similar codes. I removed the MAS and cleaned it with Berrymans carb cleaner. I installed a new air filter. I also verified that the brake assist vacuum line was tightly sealed to the throttle body. I cleaned all electrical sensor connections on the engine that I could get to. This included the cam position connections on the top front of the heads. I now have no lean conditions and no other codes. I do still ahave a cylindar 8 misfire condition that is only present when the engine is cold. This condition clears completely at normal operating temperature.