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Thread: Is the brief dip before quick acceleration a Jaguar thing?

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    Senior Member Winchester12g's Avatar
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    Is the brief dip before quick acceleration a Jaguar thing?

    With my previous auto 2.5 and 3.0 X-Types and now with my 3.0 XJ6, when I pull away a little bit quick from a standing start there's a dip of maybe half a second before it comes to life. The only other time I've experienced this was in a 2.7D Audi some years ago.

    Is this a characteristic of Jaguar engines/gearboxes or have I just been damn unlucky?!

    Is there a fix?

    Thanks.

    James
    1. I'll leave this link as a reminder to me of My First Love: http://www.jaguarforum.com/showthread.php?t=77370
    2. My beautiful 2007 X-Type 2.5 Estate (with a mid-sport exhaust) in metallic Quartz Grey was written off in Nov '17 thanks to a moron kid in a Fiesta who thought it'd be a good idea to pull off Mummy's drive with a totally misted up screen.....
    3. My new love is a pristine 2003 XJ6 X350 3.0 auto

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    Does the traction control light flicker?

    I certainly get a noticeable backing off of power if the wheels start to spin after a banzai getaway
    S Type 4.2 SE Plus 2002 original spec: Xenon HID/SatNav/Voice/Cassette Player/CDC/TV/GSM Phone/Sun Roof/Rear Blind/CATS.
    Retro-fitted: CD Player/Bluetooth Phone/Aux Power Socket, USB & Volt Meter in Boot/Reversing Cam/Dash Cam & PSU/Dual USB sockets in Armrest/
    Wireless Phone Charger under Instrument Surround.
    Pictures of technical stuff

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    My S-Type 2.7d was very soft off the line, but if anything I'd say the other Jaguars I've owned have a particularly aggressive "tip in" from a standstill. My X350 is hilarious from a standing start for a NASP Jaguar. Could be to do with the way you're feeding in the throttle? Have you tried it in S mode too?

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    Senior Member Winchester12g's Avatar
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    Quote Originally Posted by graham-r View Post
    Does the traction control light flicker?

    I certainly get a noticeable backing off of power if the wheels start to spin after a banzai getaway
    Not that I've noticed, but will look out for it now

    Quote Originally Posted by DavidEdney123 View Post
    My S-Type 2.7d was very soft off the line, but if anything I'd say the other Jaguars I've owned have a particularly aggressive "tip in" from a standstill. My X350 is hilarious from a standing start for a NASP Jaguar. Could be to do with the way you're feeding in the throttle? Have you tried it in S mode too?
    It doesn't happen in S mode - is this strange? Based on what you said about how I'm feeding the throttle I thought I'd take it out for a 'bit of a try' tomorrow, but having just seen the weather forecast it's a definite no-go!
    1. I'll leave this link as a reminder to me of My First Love: http://www.jaguarforum.com/showthread.php?t=77370
    2. My beautiful 2007 X-Type 2.5 Estate (with a mid-sport exhaust) in metallic Quartz Grey was written off in Nov '17 thanks to a moron kid in a Fiesta who thought it'd be a good idea to pull off Mummy's drive with a totally misted up screen.....
    3. My new love is a pristine 2003 XJ6 X350 3.0 auto

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    My thoughts were that if you're starting off gently and then asking for more it might be moving up to 2nd, then back down to 1st thus giving you a lack of response. In S mode it'll hang onto 1st for longer. Even without S mode if you feed the throttle in smoothly but quickly as it moves away the car should be brisk with no delays.

    There is no reason for a NASP or supercharged petrol engine to have that godawful dead spot from a standstill that automatic turbodiesels and HPT petrols often have.

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    Quote Originally Posted by DavidEdney123 View Post
    There is no reason for a NASP or supercharged petrol engine to have that godawful dead spot from a standstill that automatic turbodiesels and HPT petrols often have.
    My car doesn't have a deadspot provided I keep the wheels from spinning up as the DSC can step in rather too aggressively especially if only one wheel has broken traction. A progressive push on the throttle for the first 10% of it's movement certainly helps and makes very little difference to the overall acceleration.

    Dumping the throttle is unnecessary and not very mechanically sympathetic so whilst on occasion I do enjoy the performance I do so with a mind on keeping my drivetrain intact
    S Type 4.2 SE Plus 2002 original spec: Xenon HID/SatNav/Voice/Cassette Player/CDC/TV/GSM Phone/Sun Roof/Rear Blind/CATS.
    Retro-fitted: CD Player/Bluetooth Phone/Aux Power Socket, USB & Volt Meter in Boot/Reversing Cam/Dash Cam & PSU/Dual USB sockets in Armrest/
    Wireless Phone Charger under Instrument Surround.
    Pictures of technical stuff

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    Senior Member fat controller's Avatar
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    From a standing start when you give it plenty, mine does seem to have a small hesitation before it then kicks you in the back and takes off like a scalded cat..........

    I have a theory though, and it goes back to something that I experienced on what was a new double deck bus chassis, almost 20 years ago - - bear with me, it will make sense soon,

    These were probably the first buses to have things like high pressure common rail engines, canbus, fly-by-wire throttles and ECU control, and when we had the first few delivered it was very quickly discovered that there were occasions when you would go to pull away, usually into a gap on a roundabout or similar, and the damned things would hesitate, bog down and at best just dribble out into traffic leaving you looking like a complete muppet. Yet, if you gave it about a halfway throttle position, they would take off really quite quickly. We raised a complaint with the manufacturers, who sent in some of their techs who carried out various tests, many of which were driving with a laptop plugged in to see what was going on. In short, when a driver stuck the hammer down all the way from a standing start, the ECU would receive the signal to open the throttle fully, and it would then question it - - full power, really?? are you sure?? nah, you don't really want full power, it must be a mistake, I will give you just a bit for now and you will adjust your foot to where you really want it........... oh, you DO want full power............. by which time, you were crawling onto a roundabout with traffic bearing down on you, looking like an idiot.

    To their credit, the manufacturers queried this with the engine manufacturers, and they in turn confirmed that this was correct - - it was deemed that such was the torque output from the engine, and that it revved up so quickly in comparison to older engines, that going from a dead stop to full throttle uncontrolled would see gearboxes going south on a regular basis; furthermore, such was the torque that it from a standing start the shove would be sufficient to have any standing passengers falling over. The advice - pull away on half throttle, and when rolling stick the boot in if you really want a fast launch, and they were right.

    I wonder if cars are essentially the same - programmed to second guess what we are doing to preserve themselves, or even to conserve fuel or something?
    ex - 2002 X-Type 2.5 V6; 1995 XJ Sport 3.2; 1998 Mercedes C180 Elegance; VW Passat 2.0TDI (140); Audi A4 Avant 2.0TDI; Nissan Qashqai 1.5dCi; Current - 2007 XJ 4.2 V8 Sovereign, and occasionally an Electric Wheelchair!

    It wasn't me! A big boy done it and ran away.

  10. #8
    Senior Member Winchester12g's Avatar
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    Quote Originally Posted by fat controller View Post
    From a standing start ..........
    I'm nowhere near techy enough to concur or otherwise, but you're possibly right!
    1. I'll leave this link as a reminder to me of My First Love: http://www.jaguarforum.com/showthread.php?t=77370
    2. My beautiful 2007 X-Type 2.5 Estate (with a mid-sport exhaust) in metallic Quartz Grey was written off in Nov '17 thanks to a moron kid in a Fiesta who thought it'd be a good idea to pull off Mummy's drive with a totally misted up screen.....
    3. My new love is a pristine 2003 XJ6 X350 3.0 auto

  11. #9
    Senior Member Winchester12g's Avatar
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    Quote Originally Posted by DavidEdney123 View Post
    My thoughts were that if you're starting off gently and then asking for more it might be moving up to 2nd, then back down to 1st thus giving you a lack of response. In S mode it'll hang onto 1st for longer. Even without S mode if you feed the throttle in smoothly but quickly as it moves away the car should be brisk with no delays.

    There is no reason for a NASP or supercharged petrol engine to have that godawful dead spot from a standstill that automatic turbodiesels and HPT petrols often have.
    Quote Originally Posted by graham-r View Post
    My car doesn't have a deadspot provided I keep the wheels from spinning up as the DSC can step in rather too aggressively especially if only one wheel has broken traction. A progressive push on the throttle for the first 10% of it's movement certainly helps and makes very little difference to the overall acceleration.

    Dumping the throttle is unnecessary and not very mechanically sympathetic so whilst on occasion I do enjoy the performance I do so with a mind on keeping my drivetrain intact
    I rarely if ever go hell for leather - it's always when I want to nip out on a roundabout or a T-junction and just toe down a little harder than normal. Anything too heavy and the wheels inevitably spin before the DSC takes hold.

    Once the roads dry out next week I'll try a few different methods and see what happens.

    Cheers guys!
    1. I'll leave this link as a reminder to me of My First Love: http://www.jaguarforum.com/showthread.php?t=77370
    2. My beautiful 2007 X-Type 2.5 Estate (with a mid-sport exhaust) in metallic Quartz Grey was written off in Nov '17 thanks to a moron kid in a Fiesta who thought it'd be a good idea to pull off Mummy's drive with a totally misted up screen.....
    3. My new love is a pristine 2003 XJ6 X350 3.0 auto

  12. #10
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    The other possibility is if you have just stopped at a junction before pulling away - the gearbox may be still settling on a gear, the engine and gearbox computers will restrict power a bit, my car definitely does that if I am a bit too hasty.
    S Type 4.2 SE Plus 2002 original spec: Xenon HID/SatNav/Voice/Cassette Player/CDC/TV/GSM Phone/Sun Roof/Rear Blind/CATS.
    Retro-fitted: CD Player/Bluetooth Phone/Aux Power Socket, USB & Volt Meter in Boot/Reversing Cam/Dash Cam & PSU/Dual USB sockets in Armrest/
    Wireless Phone Charger under Instrument Surround.
    Pictures of technical stuff

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