Hi,

I have a 2000 XJR with 71k miles on it.. recently it's been acting a bit funny.

"Restricted performance" warning with yellow light comes on if I go over 75, and goes back off if I drop under 70. CEL stays on after RP warning goes away. I also had the car go into failsafe mode once, but it also went away after I shut the car off overnight and started it the next morning.

Before this started happening, it started to get sluggish/seems to be choked under acceleration unless I floor it.. doesn't happen when it's cold out before the engine has warmed up.. only if it's warm out (even when the engine is cold) or the engine is warm and it's cold out.

What could this be? MAF sensor problem?

 

Iv seen this problem many times and is usually cured with a new MAF sensor, i would say 90% of the time in my experiences. It usually doesnt set the engine light but the car wont even get out of its own way because of the false readings of the MAF.

 

I just went thru this with the same exact year car.
Yes, replace the MAF sensor. Located right on the air intake hose by the air filter.
Costs about $170.00 Takes 2 minutes to replace.

 

Cool, I'll give that a shot. Thanks!

The local precision tune said there were no diagnostic codes when they tried to get info from the computer, just a P1000 which they said was generic so I'm not sure what the restricted performance is about..

the car also seems to have some sort of rev limiter at 3000 rpm when it's not in gear.. I wonder if I actually have 2 problems, the MAF and something else

 

The rev limiter in park or neutral is normal. Kinda threw me for a bit on my XJR.

 

well that makes me feel better

still don't know why the restricted performance comes on at 70 mph, I hope a new MAF sensor will fix it

 

It will!

 

it certainly seems to have.. replaced the MAF and the car is back to its former self

restricted performance message doesn't seem to be coming on either.. so I'll wait and see a bit, but I believe that it may be resolved. Cant believe a $200 part and 5 minutes made such a difference.

thanks for your help guys

 

Thants exactly how I felt when it fixed mine!!
I love this car!!

 

well, now it's going into failsafe mode.. done it twice tonight. turn off, start it again and it's fine.. check engine light isn't even on after restarting

I wonder if fixing the MAF exposed another problem. sigh.

I recently had new brakes/rotors installed and sparkplugs changed also.. would either of these affect any systems that would cause a failsafe? it seems to happen after quick acceleration followed by coasting for 10-15 seconds.. first time it happened the engine actually stalled completely.. I wonder if I got bad gas or if there's a fuel filter/pump problem. I really need a code reader [:@]

 

So I guess the check engine light came on again.?