Restricted Performance
#1
Restricted Performance
I just did 1500+ miles in the XKR in Scotland but it was plagued with "Restricted Performance" messages every now and then. Caused by I think two problems the throttle body and the water coolant temperature sensor. I replaced the sensor the year before because it was playing up then and now I think this one is playing up. It would read that the coolant temp is too high and put the car into restricted performance mode but if you turned the car off and on again it would go away. I checked the actual coolant temp with an OBDII reader and it was at 75C so there isn't anything wrong with the cooling system there I'm pretty sure it's just the sensor. With the throttle body I would fix it by taking the intake off and giving the area around the butterfly valve a good clean out and it would go away for a while and come back again. I'm not sure how to get rid of this problem permanently does anyone know a way and also am I just unlucky coolant sensors or is there a better way to fix it then to keep buying new sensors? It's a 2003 4.2 XKR.
#2
Join Date: Jan 2018
Location: on the road in NE Oklahoma
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how old is your battery ?
It’s likely beating the old dead horse, but try a
load test on your battery or a new battery outright . These cars are exceedingly demanding when it come to having a battery in tip top shape.
many electrical faults on these cars are solved by a new battery, although seemingly there’s nothing wrong with the old one.
also, if not already being done, out the battery on a battery tender whenever the car is not being used overnight or longer. Besides extending battery life, doing this keeps many electrical gremlins away.
Z
It’s likely beating the old dead horse, but try a
load test on your battery or a new battery outright . These cars are exceedingly demanding when it come to having a battery in tip top shape.
many electrical faults on these cars are solved by a new battery, although seemingly there’s nothing wrong with the old one.
also, if not already being done, out the battery on a battery tender whenever the car is not being used overnight or longer. Besides extending battery life, doing this keeps many electrical gremlins away.
Z
The following users liked this post:
Markel (09-15-2021)
#3
how old is your battery ?
It’s likely beating the old dead horse, but try a
load test on your battery or a new battery outright . These cars are exceedingly demanding when it come to having a battery in tip top shape.
many electrical faults on these cars are solved by a new battery, although seemingly there’s nothing wrong with the old one.
also, if not already being done, out the battery on a battery tender whenever the car is not being used overnight or longer. Besides extending battery life, doing this keeps many electrical gremlins away.
Z
It’s likely beating the old dead horse, but try a
load test on your battery or a new battery outright . These cars are exceedingly demanding when it come to having a battery in tip top shape.
many electrical faults on these cars are solved by a new battery, although seemingly there’s nothing wrong with the old one.
also, if not already being done, out the battery on a battery tender whenever the car is not being used overnight or longer. Besides extending battery life, doing this keeps many electrical gremlins away.
Z
Last edited by Kuddlesworth; 09-15-2021 at 04:59 AM.
#4
The battery is brand new repalced last year by me. I also had a "gearbox fault" message on the dash at one point during the trip but it was fixed by turning off the engine and on again. Never came on again. To be fair I was using the J gate a lot and revving the engine out a lot up hills which probably isn't good. I've had it come up in the past as well but it's always gone easily. Never left any codes in the ODBII which is odd. Oil change was done at 60k miles which was only 10k miles ago so that shouldn't be a problem.
ln my experience anytime my battery drops below 85% from sitting it will throw random codes, ABS - TRAC, TRANS on the dash and also never leave codes on my ''mere mortal'' ODB reader to the point were i plug the trickle charger in every time i get home, not a code since. These are as voltage sensitive car as ive ever come across, to the point were i will change the battery at 2 years. lf i where you i would change the battery.
#5
''Brand new last year'' is not new.
ln my experience anytime my battery drops below 85% from sitting it will throw random codes, ABS - TRAC, TRANS on the dash and also never leave codes on my ''mere mortal'' ODB reader to the point were i plug the trickle charger in every time i get home, not a code since. These are as voltage sensitive car as ive ever come across, to the point were i will change the battery at 2 years. lf i where you i would change the battery.
ln my experience anytime my battery drops below 85% from sitting it will throw random codes, ABS - TRAC, TRANS on the dash and also never leave codes on my ''mere mortal'' ODB reader to the point were i plug the trickle charger in every time i get home, not a code since. These are as voltage sensitive car as ive ever come across, to the point were i will change the battery at 2 years. lf i where you i would change the battery.
#6
#8
In consideration of your damp climate it would be a good idea to remove and clean the connections of the engine to chassis ground at the right rear of the engine and both battery cables.
If you are able to use a battery maintainer, such as a CTEK that would extend the life of the battery.
A generic code reader will not read the transmission codes.
If you are able to use a battery maintainer, such as a CTEK that would extend the life of the battery.
A generic code reader will not read the transmission codes.
#9
In consideration of your damp climate it would be a good idea to remove and clean the connections of the engine to chassis ground at the right rear of the engine and both battery cables.
If you are able to use a battery maintainer, such as a CTEK that would extend the life of the battery.
A generic code reader will not read the transmission codes.
If you are able to use a battery maintainer, such as a CTEK that would extend the life of the battery.
A generic code reader will not read the transmission codes.
Edit: I could only find my engine block ground and that looks a bit green so I suppose that could be the problem. My battery contacts and fuses all look good though at least the ones I could find. I couldn't find the very front ground point and not the transmission ground either. I suppose I will have to get the car jacked up to find them? I might see if I can clean all my connectors and see if that helps or I've read there is a large connector under the car that goes into the transmission.
Last edited by Kuddlesworth; 09-15-2021 at 11:01 AM.
#10
#11
The 6HP26 transmission does have a problem with fluid getting into the cable and causing trouble, so not a bad idea to replace the sleeve. I don't think there is a transmission ground, just the strap from the bell housing to the frame accessed from underneath on the right side.
#12
I just did 1500+ miles in the XKR in Scotland but it was plagued with "Restricted Performance" messages every now and then. Caused by I think two problems the throttle body and the water coolant temperature sensor. I replaced the sensor the year before because it was playing up then and now I think this one is playing up. It would read that the coolant temp is too high and put the car into restricted performance mode but if you turned the car off and on again it would go away. I checked the actual coolant temp with an OBDII reader and it was at 75C so there isn't anything wrong with the cooling system there I'm pretty sure it's just the sensor. With the throttle body I would fix it by taking the intake off and giving the area around the butterfly valve a good clean out and it would go away for a while and come back again. I'm not sure how to get rid of this problem permanently does anyone know a way and also am I just unlucky coolant sensors or is there a better way to fix it then to keep buying new sensors? It's a 2003 4.2 XKR.
When was the last time you cleaned the MAFS?
#13
#14
Get the real CRC MAFS cleaner and clean BOTH wires good JUST WITH SPRAY. Don't touch it with anything.
Gus has great info here:
MAFS Reading
MAFS Cleaning
Last edited by srpope80; 09-15-2021 at 03:01 PM.
#15
One of the things that get overlooked on these are the fuel filters and MAFS. My craiglist cat ('01 XK8) was original fuel filter, and air could barely go through it. @rothwell Happened to drop by one day with and extra Fuel Filter he happened to have.... When does that ever happen?! . That and the MAFS was dirty as all get out. Threw restricted performance codes anytime I tried to rev over 3k.
Get the real CRC MAFS cleaner and clean BOTH wires good JUST WITH SPRAY. Don't touch it with anything.
Gus has great info here:
MAFS Reading
MAFS Cleaning
Get the real CRC MAFS cleaner and clean BOTH wires good JUST WITH SPRAY. Don't touch it with anything.
Gus has great info here:
MAFS Reading
MAFS Cleaning
#16
It's a good start to check, but I'm going to start adding the MAFS cleaning to my "yearly" once over checklist. Easy to do, just spray it good and let it dry. Put back in. I didn't even get sweaty.
#17
#18
Is there anyone in the UK that can rebuild them? I've seen a place that can do the 4.0 throttle body but they don't list the 4.2.
#19
I bought some MAFS cleaner and throttle body cleaner so I can give it all a good clean. Just have to wait for it to come down.
Last edited by Kuddlesworth; 09-16-2021 at 03:30 AM.