Though I had my own thread going about this, figured I would reply to yours in hopes it helps you. I had the same type of issue. There is a thread here with instructions on how to clean out the MAF sensor. I performed this function ($5 can of CRC spray) and the car is back to new again. I was amazed how this improved, my mileage has shot back up and I no longer have any hesitation.

I did check the partial load tube, an easy way to check for its condition was to pull it from the valve cover (no easy task) and press your thumb over the tube opening. Vacuum should pull your skin tight while the engine is running at idle and no hissing anywhere else should be heard (over engine noise can be hard to hear). Just kind of a shade tree mechanic way of checking the hose, since all that is needed here is vacuum to determine that the hose should be working well enough to function.

I also performed the 'clearing' of the valve cover side, though I did not use a drill bit, instead found a wire of roughly the same diameter and bent a loop in the other end so that it could not fall down inside the valve cover. Mine though was not obstructed.

 

"R" motors have a rev limiter at idle so you don't rev the motor past 3000 RPM at vehicle rest.

 

Well that would make sense, as I don't typically rev the motor past 2k while parked and working on it.

The MAF cleaning has worked wonders on my car though, feels like it did when I first bought it.

One thing though, removing the negative battery terminal did not clear the engine light. I also did the positive one and as well unplugged totally the ECU. Nothing has reset the light, in the past it has just shut off but it has been on now for a couple days.

Engine codes were just about running lean problems, which feels like cleaning the MAF sensor has resolved (as the symptoms are no longer there). Will the system eventually reset itself or is there another way to clear the code without dealer involvement?

 

update - my engine codes cleared by itself after about 2 days.

 

Nice portland, now relax and enjoy the ride for awhile will ya? Glad to hear the MAF cleaning worked to clear you codes. Hope you can stick around and help someone else down the road.

 

Thanks for explaining the Rev limiter on my XKR at 3000 rpm at idle. This worried me, as I had just had all of the timing plastic parts done & it popped on the left pipe at 3000 rpm. I was thinking one of valves was worn. Feel happier that all is in order.