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Since buying my 1995 xjr I have had issues with the throttle sticking at about 1200-1300 rpm after releasing the throttle. And to make it go down I will "kick" the pedal. This issue did not bother me too much however now I have gotten worse issues. Now when I drive while having an even amount of press on the gas pedal the engine will rev up and down in an uneven and jerky fashion, The idle has also started to become uneven sometimes. This is new. I recently installed a new programmed ECU with no immobilizer to fix my no-start issue so I hope it's not the new ECU that's causing the problem. I have read that a throttle-body cleaning might do the trick but since it seems to be quite hard to access I thought I would ask here for tips on where to start. What are the simple first checks to do and if it comes to cleaning the throttle body how do I go about doing it with as little hassle as possible?
I will attach a video demonstrating the sticking RPM.
What motorcarman says .
it strikes me that your idle is on the high side even after you have blipped the throttle to get it to drop below 1000. I couldn’t see your temperature gauge so it may have been a cold start, but you might want to have a look at the numerous threads on high idle, and the various potential causes.
The throttle body can be removed from below, and having tackled it both ways on the supercharged car, it is the much easier way, although easy wouldn’t be the first word I’d use to describe it. A lift and long arms are very useful!
It was a cold start. But I always get a sticking high idle when releasing the pedal from higher revs while driving and also when going from D to P and have to blip the throttle to make it go down. Since I have a lift I will try to go at the TB from underneath. Anything Important I should think about before starting the job? Should I replace some parts while I am at it? Will I have to adjust something in the process?
Since buying my 1995 xjr I have had issues with the throttle sticking at about 1200-1300 rpm after releasing the throttle. And to make it go down I will "kick" the pedal. This issue did not bother me too much however now I have gotten worse issues. Now when I drive while having an even amount of press on the gas pedal the engine will rev up and down in an uneven and jerky fashion, The idle has also started to become uneven sometimes. This is new. I recently installed a new programmed ECU with no immobilizer to fix my no-start issue so I hope it's not the new ECU that's causing the problem. I have read that a throttle-body cleaning might do the trick but since it seems to be quite hard to access I thought I would ask here for tips on where to start. What are the simple first checks to do and if it comes to cleaning the throttle body how do I go about doing it with as little hassle as possible?
I will attach a video demonstrating the sticking RPM.
Hi,
I bought a 97 XJ6 a few weeks ago and was also having a sticky throttle. The car had been idle for a couple of years so I thought it might loosen up with use. It did a little but not enough to make it feel completely safe.
So! I left it in to my local Brit car specialist Octagon Vancouver and they cleaned the carbon out of the throttle and the car now runs like silk. Worth doing just for the feel of it. I also makes parking easier as the acceleration is less jumpy.
I would be tempted to have a look at the threads on throttle cable adjustment before diving in to removing the throttle body. Much less difficult although following the specific guidance is advised. There are two cables and although no tools are required to adjust them, there is a knack to the adjustment.
Going from D to P and a error accrues before touching the throttle to goose it down points to regulation and not so much a sticking throttle cable
Your GM transmission does not have a rotary position switch that can be hanging between positions
So what does come into play , the not in park switch ?
You can move the shift lever slightly out of the park gate and you can feel the switch make by placing you finger on the ignition key barrel and feel the barrel solenoid click
Last edited by Parker 7; Nov 21, 2023 at 01:17 AM.
In foot off throttle begins the IAC valve scheduling though it's open position steps / amounts to a final idle slight open position
Vee had a IAC valve test that may or may not give you a final fail / pass result least see in go through its paces
At idle The EGR valve should be closed and it has a position sensor in it that should read 0.7 volts DC on REd / Pink wire , or 0 % ERR_Error as a ELM 327 device reading
The IAC valve does not have a position sensor it it to confirm position
Some from reading have recovered their idle with EGR cleaning from my reading , but then you may not have one
The secondary air ( smog ) pump should be off , there is a check valve with a solenoid and diode ( wire loom ) in the pump along with a piping check valve on the right side for the supercharged setup
Last edited by Parker 7; Nov 21, 2023 at 10:10 AM.
According to my Bluetooth OBD2 Reader, my idle TP is 11.37% is this normal?
I managed to get the throttle to stick at 13 and 15% TP. Following the cable I found some sort of bad repair the previous owner had done (check the attached images.. Could this have something to do with anything? I will also attach a video of a poor lower idle after driving for a bit.
Any tips for a more quality OBD2 scanner that works with 95' XJR ?
The factory spec is 0.60 + or - 0.o2 volts DC on the middle wire on the TPS connector with it still installed to be powered by a precise reference 5.0 volts , key on engine not running
One example did come it higher
Is the ECU the exact same as the original , I see it was modified but has to be the same serial number
your later higher TPS does point to throttle cable drag
going to dialysis chair and will have more in a couple hours as i become more pure
Do not remove cabling from the top of the vertical cylinder ( traction control actuator ) in your pic as can be a pain to put back together but do look on the very bottom and you may see 2 wires with insulation coming off ( brittle insulation ) common
Last edited by Parker 7; Nov 25, 2023 at 09:03 AM.
I had a 1995 XJR as a daily driver for many years. Your high idle problems are familiar to me. Unfortunately details of the repairs are not always clear in my memory these days
I do remember cleaning the throttle body a few times over the years, the updated springs, and problems with the cables to-and-from the Trac Control unit, including the broken cable seen in your photo.
The cables were especially problematic for me. There's an official adjustment procedure which, honestly, never seemed to work right and never made much sense to me. I concluded (not necessarily correctly!) that one of the cable had become stretched a bit, thus flummoxing the adjustments. The adjustment procedure has been posted here and I'm sure a simple archive search will bring it up.
Any tips for a more quality OBD2 scanner that works with 95' XJR ?
Years ago there wasn't much available at DIYer the price range. Any OBDII scanner will cover the simple basics (I used an Innova 3130) but I often wished it had more capability. I sure things have improved and others will chime in on what's presently available.
I had many problems with [what seemed to be] phantom codes, reluctance of the OBD to set codes, fuel trims, and scan tool readings that simply made no sense. Experienced dealer techs who post here have explained that the OBDII for 1995 was "not fully developed" and was a bit notorious for, well, weird things. This complicated repairing the numerous driveability issues I had with the car over the years.
The stickers is if done fully in a Jaguar shop , but if done at home ................
You can open the ECU and visually see the large numbers on the EPROMS chips
Your supercharged TB is a little bit different than my normally aspirated so the Ebay spring is in question if it would work for you
There was some pics and instructions of someone using the original spring and you can do that for free
If there was a definite connection in your observed engine behavior before and after the ECU swap then you might have a mis matched TPS to ECU pair
The ECU is " orientated " told what the idle null value is as may be 0.58 to 0.62 volts DC , this takes special equipment to orient the ECU to the TPS fixed position , but the holes on the plastic body can be drilled up a size to give you some adjustment on the TPS fixed position
To take that step takes a commitment that the other issues have been looked at
Wether on not the TSB was accomplished or not would have no effect on the TPS / ECU matching
Do you have the dedicated external ECU case to ground strap installed ?
Correct supercharger ECU part # as thay have different maps even though the hardware is the same
Last edited by Parker 7; Nov 26, 2023 at 10:11 AM.
With your white plastic throttle cable piece at the traction control actuator replaced it might tighten up your throttle cable
on the later X300 models they had turnbarrels on the run from the actuator to the TB butterfly
This is on a document someone ( contributor named CDMA ) had as my 96 ( VIN # 75XXX ) does not have this even though it does have the traction control option
Last edited by Parker 7; Nov 26, 2023 at 10:41 AM.
I don’t have the supercharged engine, nor do I have the x300 (I have a 96 XJS with the AJ16, normally aspirated engine)
Over the years I’ve read plenty about people with sticky throttles. If I put the most common solutions in order, it would probably look like this:
1. Clean throttle body (off the engine, so you can get to both side of the butterfly)
2. Reset TPS. (I believe proper % open is 12.9% at idle, even for x300?)
3. Modify spring, or add spring. Modifying the existing coil spring by adding a turn seems to be helpful to more people than adding the additional spring.
4. Replacing the throttle cable. In few instances, the cable is damaged and a kink is catching somewhere.
I think that’s it. I would say Solutions 1 & 2 make for the vast majority of the fixes.
RPM issues sticky throttle. XJR6 95'
