XJ XJ8 / XJR ( X308 ) 1997 - 2003

Need your help! Please help!

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Old Feb 27, 2013 | 05:25 PM
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Hi all,

I have a problem that I really need some help on. I am sure someone here can help me out with your experience and knowledge. Anyways, I have had a code come up a couple of times, P0174. Well, I did lots of reading on here and saw some great threads about the issue and what it could be. So I followed the cleaning procedures recommended on here and after everything was done I also did a hard reset following the instructions. Great info and it solved the problem. I haven't seen the light come one since. However, now, I can't seem to launch from a stand still and burn rubber off the starting line like I can before. Clueless and not knowledgeable enough about these beautiful cars, I checked for cracks at the intake as stated by some on here. I also checked to see if the sports mode button was working properly, as from what I understand and have read, it starts the car from 1st gear. Hoping that that will help it launch off correctly like before. Nothing! It still lags at the launch. I pressed the button on and off while at a stand still and did not feel or hear any difference in the idle or movement of the car. As I recall, when it still burns rubber from a stand still in the past, the car seemed to very slightly engage in a jerk when the sports mode is set to on (when listening carefully). The red light on the button still comes on but I just don't feel anything and the performance of the car is just isn't like how it used to be. Does anyone know if there is a fuse or anything that turns the sports mode on, other than the button, that may have been blown or broken? Or does anyone ever experienced this or have any idea for this fix? Please help with your expert advise and experience. Your input and help will be greatly appreciated. Thanks much in advance.

UPDATE:...

It turns out the sports mode works fine and traction control turns on/off fine. Clueless of what the cause may be, but I came to a crazy thought. After all this and thinking about it, I had a thought and I want to make sure I didn't screw myself. Now, this may be a stupid thing to ask, but I guess you never know unless you ask. When I bought the car, it came with an after market muffler and K&N filter on. I was thinking. What if the previous owner got a software tune and when I did the hard reset, it cleared that software. Is this possible? I came to this thought because it felt very fast and felt like it had lots of torque and now it feels nothing close to that.

Dev
 

Last edited by devxiav; Feb 28, 2013 at 11:28 PM.
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Old Feb 27, 2013 | 06:09 PM
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"So I followed the cleaning procedures recommended on here"

Which is.... What exactly did you do and what did you clean?
 
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Old Feb 27, 2013 | 07:19 PM
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Originally Posted by dsnyder586
"So I followed the cleaning procedures recommended on here"

Which is.... What exactly did you do and what did you clean?
Thanks for the quick response. I cleaned the part load breather, the MAFS, the intake, the TB ( I just wiped the TB clean because some on here recommend to not spray anything into it), etc.
 
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Old Feb 27, 2013 | 07:39 PM
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By the way. My car is a 1998 XJR, 4.0. Thanks
 
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Old Feb 27, 2013 | 07:42 PM
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I might be wrong, but maybe you should look into the traction control?
 
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Old Feb 28, 2013 | 12:30 PM
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Originally Posted by danielsand
I might be wrong, but maybe you should look into the traction control?
Thanks for the response. I did check it. How I checked it is adding a small water puddle and onto the asphalt and turn off the traction control. By doing that, the car can peel out to redline when I do a burn out.
 
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Old Feb 28, 2013 | 09:25 PM
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So, I found out that the sports mode still works as well as the traction control. I have no clue what to do next or even where to start. Any ideas? Any help will be greatly appreciated. Thanks much in advance.
 
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Old Mar 1, 2013 | 12:39 AM
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Don’t have a direct answer, but there are some more checks you could do.

If there was a tune, it would still be there after a battery disconnect.

The lean issue is not an off/on situation, althoug the code is, as you get it when there is more than 20% deviation (ltft value). So if after your cleaning it would be 19% now, there would still be a problem, but the code will not be triggered.

Best to check your ltft figures, at idle and different speeds (i.e. 30 and 50mph), always ensure you drive at a constant speed and let the ltft settle before taking the measurement.

Also check your throttle opening, so ignition on, and press the pedal to the metal, and see if you get 100% opening on the odbii tool.
 
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Old Mar 1, 2013 | 11:31 AM
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Originally Posted by avos
Don’t have a direct answer, but there are some more checks you could do.

If there was a tune, it would still be there after a battery disconnect.

The lean issue is not an off/on situation, althoug the code is, as you get it when there is more than 20% deviation (ltft value). So if after your cleaning it would be 19% now, there would still be a problem, but the code will not be triggered.

Best to check your ltft figures, at idle and different speeds (i.e. 30 and 50mph), always ensure you drive at a constant speed and let the ltft settle before taking the measurement.

Also check your throttle opening, so ignition on, and press the pedal to the metal, and see if you get 100% opening on the odbii tool.
Thanks much for the response. Really appreciate it
 
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Old Mar 1, 2013 | 02:34 PM
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How far have you driven the car since doing the work? After the hard reset it's possible you may not have driven far enough yet for the car to have adapted & learnt the new settings required for optimum operation.

When the upstream O2 sensor failed in my 2001 XJR, it threw up the fault code & the Check Engine light illuminated. I also noticed that the edge had gone off the power.

So I checked the stall speed by holding the car on the brakes in gear with the left foot, & then flooring the gas pedal with the right foot for about 5 seconds. The engine speed settled at an indicated 1500rpm.

After I fitted the new O2 sensor & erased the fault code, I did a stall speed test again & it gave the same 1500rpm. However, after a drive around I did another stall speed test & this time it gave 1800rpm. Also, all the power was back as well.

What had happened was that after the repair & erasure of the ECM to clear the fault code, the system was in it's 'raw' state & not yet adapted to the new operating conditions with the repair now done & the fault cleared.

After going for a drive around, everything returned to normal again.

If you are not getting any fault codes now, then try going for a drive of around 50 miles or so & see how the car feels after that.
 
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Old Mar 1, 2013 | 03:20 PM
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Originally Posted by Red October
How far have you driven the car since doing the work? After the hard reset it's possible you may not have driven far enough yet for the car to have adapted & learnt the new settings required for optimum operation.

When the upstream O2 sensor failed in my 2001 XJR, it threw up the fault code & the Check Engine light illuminated. I also noticed that the edge had gone off the power.

So I checked the stall speed by holding the car on the brakes in gear with the left foot, & then flooring the gas pedal with the right foot for about 5 seconds. The engine speed settled at an indicated 1500rpm.

After I fitted the new O2 sensor & erased the fault code, I did a stall speed test again & it gave the same 1500rpm. However, after a drive around I did another stall speed test & this time it gave 1800rpm. Also, all the power was back as well.

What had happened was that after the repair & erasure of the ECM to clear the fault code, the system was in it's 'raw' state & not yet adapted to the new operating conditions with the repair now done & the fault cleared.

After going for a drive around, everything returned to normal again.

If you are not getting any fault codes now, then try going for a drive of around 50 miles or so & see how the car feels after that.
Thanks much for the help and advise. I have driven the car approximately 80 miles since the hard reset. Today, the code came back on. However, this time I got a few codes. I got the P0174, P1797, and P1000. I will definitely try the 02 this weekend. Will keep updates. If any advise on why these codes came on together please help with your suggestions. Thanks
 
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Old Mar 1, 2013 | 07:23 PM
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Hi
Here are 2 DTC Summaries PDF files for your 1998 XJR (when the dropbox webpage opens click on the download button, then use Direct download option):

Engine Management (lookup P0174):

https://www.dropbox.com/s/70vfd5o9zr...Management.pdf

W5A-580 Transmission Control (lookup P1797):

https://www.dropbox.com/s/jsl7fr12ph...ansmission.pdf

DTC P1000 is logged in memory, the on-board diagnostic tests have not been completed.

Jim Lombardi
 

Last edited by jimlombardi; Mar 1, 2013 at 07:29 PM.
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