Restricted Performance
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Junior Member
Joined: Jan 2015
Posts: 2
Likes: 0
From: Ponca Cty, OK
Restricted Performance
My 2004 S-type jag is in "Restricted Performance" mode. If I sit at idle in park for about 5 min the light goes off and if I get on the highway it goes off. But around town when running in mid-range the light comes on and goes to "Restricted Performance." I've had ALL the gaskets replaced and the smoke test showed NO LEAKS.
The codes are P0171 P0174. The oxygen sensors are working with the correct voltage, I put in a new MAF sensor, new plugs, new air cleaner and cleaned out the throttle body. The fuel pressure is running normal and I've added injector cleaner several times.
Any ideas?
The codes are P0171 P0174. The oxygen sensors are working with the correct voltage, I put in a new MAF sensor, new plugs, new air cleaner and cleaned out the throttle body. The fuel pressure is running normal and I've added injector cleaner several times.
Any ideas?
Senior Member
Joined: Nov 2013
Posts: 185
Likes: 50
From: Canberra, ACT
Hiya,
Firstly can I recommend not throwing parts at it, a more diagnostic approach is better. Now this might sound very simplistic, but have you cheched the battery? Low voltages are one of the many, many causes for your symptoms. Check it once the car has been off for more that 40 minutes, check it whilst its being started and check it at idle. One failing cell can confuse the computers and the 101,174 codes are commonly spat out.
Failing that can you data log the major sensors whilst driving as see if there is any cause for the restricted performance... (But my money is on the battery!)
Donna
Firstly can I recommend not throwing parts at it, a more diagnostic approach is better. Now this might sound very simplistic, but have you cheched the battery? Low voltages are one of the many, many causes for your symptoms. Check it once the car has been off for more that 40 minutes, check it whilst its being started and check it at idle. One failing cell can confuse the computers and the 101,174 codes are commonly spat out.
Failing that can you data log the major sensors whilst driving as see if there is any cause for the restricted performance... (But my money is on the battery!)
Donna
Veteran Member
Joined: Feb 2009
Posts: 8,020
Likes: 1,731
From: Sunny South Carolina
OP, I hope you did not use cheap generic coils, MAF etc... But what do I know.
Here is a link that if you wish to follow will aid in your diagnosis:
https://www.jaguarforums.com/forum/s...ics-faq-52720/
Here is a link that if you wish to follow will aid in your diagnosis:
https://www.jaguarforums.com/forum/s...ics-faq-52720/
Veteran Member
Joined: May 2009
Posts: 12,090
Likes: 3,366
From: home
Read up on this forum.
You have a V-6 which has a well known list of defects/problems. The good thing is they are not too expensive and you can DIY them. Plus if you are smart they can ALL be fixed at the same time because you don't want to remove the intake more then once.
You have a vacuum leak and be sure and replace the IMT o-rings too.
If you can't DIY them it will be a large bill.
So get your parts list written up-order ALL the parts at once and do the repair.
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You have a V-6 which has a well known list of defects/problems. The good thing is they are not too expensive and you can DIY them. Plus if you are smart they can ALL be fixed at the same time because you don't want to remove the intake more then once.
You have a vacuum leak and be sure and replace the IMT o-rings too.
If you can't DIY them it will be a large bill.
So get your parts list written up-order ALL the parts at once and do the repair.
.
.
.
Senior Member
Joined: Mar 2016
Posts: 630
Likes: 133
From: Near Berlin Germany
Have a look at your fuel trims because that is the easiest way to see if you have an air leak
watch this video
https://m.youtube.com/#/watch?v=5WnM_NsOtd8
or this one
https://m.youtube.com/#/watch?v=oRX2V6_a3dc
they explain how to look for the leak using the fuel trims.
It really works.
watch this video
https://m.youtube.com/#/watch?v=5WnM_NsOtd8
or this one
https://m.youtube.com/#/watch?v=oRX2V6_a3dc
they explain how to look for the leak using the fuel trims.
It really works.
