2001 XKR with 23K miles--When I picked up the car last April I was averaging ~18mpg. I am averaging ~15mpg now. No difference in driving or performance. I know the plugs are original and I plan on changing them when the weather gets a little warmer.

Are the plugs the probable cause being 7 years old even though not much mileage on them?? Any other suggestions such as EFI adjustment

Gary

 

No adjustments. Clogged air filter? Part load breather clogged? I would suspect air delivary before spark. If not running rough, likely not plugs. But no harm in changing them anyway.

 

What kind of fuel are you feeding her? Race Track 89 Octane...or Exxon/Shell/Mobil 93? this made a huge difference in prior vehicles. Can you borrow a scanner with real time O2 sensor readings? That can tell you if you are running too rich...could be a sensor going bad.

 

O2 sensors is my "guess" since I have little experience with AJ26/27 engines.

PS THX H20 4 PM MSG - G

 

well some good suggestions--I have been running plus (89 octane) performance has been fine. I have hecked the air filter--didn't seem clogged but I will change anyway. I have no access to scanner so maybe I will get the o2 sensor checked--would a bad O2 sensor give me some sort of error message or light

gary

 

winter gas?

 

Fuel filter check/changed also...running 89 octane may be your problem, manual recommends 91 as a minumum. Just saying.

As for the O2 sensor, I think it has to be constantly out of spec, and perhaps it isn't doing it enough for a MIL to appear, but a DTC code may have been thrown, won't know until you check w/ a scanner. A technician care to elaborate?

 

O2 sensors will flag codes almost immediately due to emissions regs.

89 octane will definitly show loss of mileage. Spend the extra $3 per tank and you will see a noteable difference after a few fill ups. Also clean you injectors if you have been running cheaper gas through them for a while.

 

^^ yah, I was going to say that too. Really.[sm=smiley24.gif]

 

Whats the effect of 89 octane?

Does ECU pull back on timing? Thus causingengine to drop out of optimal power curve?

gordo