High idle cured?
#1
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So, like many others here, I have been beset by the "high idle syndrome". Twice, while at a main dealer on a seperate matter, the TPS was reset/tuned or whatever they do to it! It seemed to cure it, but it returned again and the second reset was done for free. Anyway, I did all the usual things, TB clean, return spring replaced with a beefed up version. Idle speed control valve replaced, AFM replaced etc. etc. Fortunately, I have a donor car, so the process of elimination wasn't too painful. Still no joy, with it coming and going until it became more constant, idling between 1800 and 2000 rpm. I wished for the old days when the idle was adjusted by a simple turn on the throttle stop screw..................so I thought, what is there to lose?
The screw in question is on the side of the throttle body, facing towards the front of the car. It is a small grub screw, adjusted with an allen key and is accessible without having to take anything apart. Its a tight spot, so an allen key with a short end is advisable, or maybe just shorten one? Dont know the exact size, but its small!
Anyway, I turned the screw back a bit, ran the engine and noticed a slight drop, back another bit and the idle was noticeably lower on the rev counter, another tweak and I got it settled on 700 rpm! I then had to take a 60 mile trip and arrived with it still idling at 700! We shall see how it goes, but I suspect that over time components including the ecu try constantly to manage a system that has gone out of sync somewhat, so that replacing parts just gives it new work to do. Whatever the reasons, this simple approach seems to have worked. Watch this space! Incidentally, there was no effect on the general running when driving, everything did what it was supposed to do.
May be worth a try if all else fails, or even before you start getting into the complicated and costly stuff.
The screw in question is on the side of the throttle body, facing towards the front of the car. It is a small grub screw, adjusted with an allen key and is accessible without having to take anything apart. Its a tight spot, so an allen key with a short end is advisable, or maybe just shorten one? Dont know the exact size, but its small!
Anyway, I turned the screw back a bit, ran the engine and noticed a slight drop, back another bit and the idle was noticeably lower on the rev counter, another tweak and I got it settled on 700 rpm! I then had to take a 60 mile trip and arrived with it still idling at 700! We shall see how it goes, but I suspect that over time components including the ecu try constantly to manage a system that has gone out of sync somewhat, so that replacing parts just gives it new work to do. Whatever the reasons, this simple approach seems to have worked. Watch this space! Incidentally, there was no effect on the general running when driving, everything did what it was supposed to do.
May be worth a try if all else fails, or even before you start getting into the complicated and costly stuff.
Last edited by sogood; 09-06-2012 at 03:45 PM.
#2
#3
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..... idling between 1800 and 2000 rpm......a small grub screw, adjusted with an allen key and is accessible without having to take anything apart. .......
Anyway, I turned the screw back a bit, ran the engine and noticed a slight drop, back another bit and the idle was noticeably lower on the rev counter, another tweak and I got it settled on 700 rpm! .
Anyway, I turned the screw back a bit, ran the engine and noticed a slight drop, back another bit and the idle was noticeably lower on the rev counter, another tweak and I got it settled on 700 rpm! .
My 95 XJ6 is experiencing the same problem today with 1500 rpm at "N" and 900 rpm at "D",
Did your problem come back? I will probably do the adjustment this weekend.
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#4
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Thanks for the tips, I am also finding a good old simpler way to adjust the idling speed without going through the TB and ECU.
My 95 XJ6 is experiencing the same problem today with 1500 rpm at "N" and 900 rpm at "D",
Did your problem come back? I will probably do the adjustment this weekend.
![Icon Dance Cpatch](https://www.jaguarforums.com/forum/images/smilies/icon_dance-cpatch.gif)
My 95 XJ6 is experiencing the same problem today with 1500 rpm at "N" and 900 rpm at "D",
Did your problem come back? I will probably do the adjustment this weekend.
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#5
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Hi,
Over the weekend,
I was not able to find the said " small grub screw adjustable with an allen key" on the TB, so, I tried a few things, the RPM still idles around 1500 on P or N gears.
Would you advise me more detail if with a photo on where the "grub screw" is?
Thanks in advance.
Mine is a 95 X300 3.2L, this shouldn't make the TB much different, I hope.
Over the weekend,
I was not able to find the said " small grub screw adjustable with an allen key" on the TB, so, I tried a few things, the RPM still idles around 1500 on P or N gears.
Would you advise me more detail if with a photo on where the "grub screw" is?
Thanks in advance.
Mine is a 95 X300 3.2L, this shouldn't make the TB much different, I hope.
#6
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Hi,
Over the weekend,
I was not able to find the said " small grub screw adjustable with an allen key" on the TB, so, I tried a few things, the RPM still idles around 1500 on P or N gears.
Would you advise me more detail if with a photo on where the "grub screw" is?
Thanks in advance.
Mine is a 95 X300 3.2L, this shouldn't make the TB much different, I hope.
Over the weekend,
I was not able to find the said " small grub screw adjustable with an allen key" on the TB, so, I tried a few things, the RPM still idles around 1500 on P or N gears.
Would you advise me more detail if with a photo on where the "grub screw" is?
Thanks in advance.
Mine is a 95 X300 3.2L, this shouldn't make the TB much different, I hope.
Hope this helps.
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charliechang33 (10-04-2012)
#7
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#9
#10
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Yup.
You'll need a TPS Reset. You might be able to do that on your own, if you're willing to manually adjust the TPS on the throttle. It's a little bit of working in the dark. (If you search the forums, you'll find posts on how it's done manually)
OR
You can find a shop that has a diagnostic computer with specialized Jaguar software.
The Jag Dealer should only charge you for 1 hour of labor, even though it'll take them 20 minutes tops.
You'll need a TPS Reset. You might be able to do that on your own, if you're willing to manually adjust the TPS on the throttle. It's a little bit of working in the dark. (If you search the forums, you'll find posts on how it's done manually)
OR
You can find a shop that has a diagnostic computer with specialized Jaguar software.
The Jag Dealer should only charge you for 1 hour of labor, even though it'll take them 20 minutes tops.
#11
![Default](/forum/images/icons/icon1.gif)
Hi,
Over the weekend,
I was not able to find the said " small grub screw adjustable with an allen key" on the TB, so, I tried a few things, the RPM still idles around 1500 on P or N gears.
Would you advise me more detail if with a photo on where the "grub screw" is?
Thanks in advance.
Mine is a 95 X300 3.2L, this shouldn't make the TB much different, I hope.
Over the weekend,
I was not able to find the said " small grub screw adjustable with an allen key" on the TB, so, I tried a few things, the RPM still idles around 1500 on P or N gears.
Would you advise me more detail if with a photo on where the "grub screw" is?
Thanks in advance.
Mine is a 95 X300 3.2L, this shouldn't make the TB much different, I hope.
#12
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See the previous post about getting your TPS reset.
I have seen some throttle bodies with an idle air adjustment screw, but neither of my two AJ16 engines had them. I would ignore that recommendation. If you hunt long enough, you'll find a post with a picture of their throttle body showing a screw where you probably don't have one.
If you're throttle body is clean, and you have to take it off the car to clean it, which is easy, AND you can confirm you have no vacuum leaks, a TPS reset will cure your issue. You can also check some other sensors, such as the coolant temp sensor, and the MAF, but the TPS will have to be reset, or manually adjusted, which takes a little work.
If you have a lumpy idle, where the rpms will constantly hunt, then that's a different problem. (probably oxygen sensors)
I have seen some throttle bodies with an idle air adjustment screw, but neither of my two AJ16 engines had them. I would ignore that recommendation. If you hunt long enough, you'll find a post with a picture of their throttle body showing a screw where you probably don't have one.
If you're throttle body is clean, and you have to take it off the car to clean it, which is easy, AND you can confirm you have no vacuum leaks, a TPS reset will cure your issue. You can also check some other sensors, such as the coolant temp sensor, and the MAF, but the TPS will have to be reset, or manually adjusted, which takes a little work.
If you have a lumpy idle, where the rpms will constantly hunt, then that's a different problem. (probably oxygen sensors)
#13
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I have a lumpy idle after the cars been running for a few minutes. It’s fine before and also fine when fully heated up ?
I replaced one o2 sensor to cure rich running and bad emissions a couple of weeks ago and the fuel mpg has increased dramatically and the emissions. Are now fine !
bit would that lumpy idle be the old o2 sensor not keeping up with the new one possibly 🤔
I replaced one o2 sensor to cure rich running and bad emissions a couple of weeks ago and the fuel mpg has increased dramatically and the emissions. Are now fine !
bit would that lumpy idle be the old o2 sensor not keeping up with the new one possibly 🤔
#14
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