[x300] XJR Throttle Response

The ex Jaguar engineer Peter Taylor in his magazine writings used to
complain that there was delayed response in the supercharged car to
snapped open throttle from idle. The “throttle police” programme
delayed the opening to fit an algorithm, thus limiting the engine
response. He writes that this has been cured on the later cars.

Have owners of supercharged cars noticed this?

Peter Smith

Not really,… mine will spin the tyres fairly easily from a complete stop,
till the traction control takes over ,should I ever put the boot into like
that…

Dean
95XJR Sydney-----Original Message-----
From: owner-x300@jag-lovers.org [mailto:owner-x300@jag-lovers.org] On Behalf
Of Peter Smith
Sent: Sunday, 16 August 2009 11:15 AM
To: x300@jag-lovers.org
Subject: [x300] XJR Throttle Response

The ex Jaguar engineer Peter Taylor in his magazine writings used to
complain that there was delayed response in the supercharged car to snapped
open throttle from idle. The “throttle police” programme delayed the
opening to fit an algorithm, thus limiting the engine response. He writes
that this has been cured on the later cars.

Have owners of supercharged cars noticed this?

Peter Smith

In reply to a message from Peter Smith sent Sat 15 Aug 2009:

not sure how with the xj6 cars as these were cars from the trottle
cable generation, wasnt until the aj-v8 came about that the fly by
wire throttle body was introduced.
i always thought the lag was due to the transmission…never cared
much for an auto box which is why im looking to source a manual for
mine.
better gas mileage and just more fun when you get down to it.–

Yes, I know what you mean…I think.

On mine I wouldn’t characterize it as a delay or hesitation but its not a
“crisp” response…it doesn’t “zing”.

Cheers
Doug Dwyer
Longview Washington USA
1995 XJRFrom: “Peter Smith” currency20@bigpond.com

The ex Jaguar engineer Peter Taylor in his magazine writings used to
complain that there was delayed response in the supercharged car to
snapped open throttle from idle. The “throttle police” programme delayed
the opening to fit an algorithm, thus limiting the engine response. He
writes that this has been cured on the later cars.

Have owners of supercharged cars noticed this?

Peter Smith

In reply to a message from Doug Dwyer sent Sat 15 Aug 2009:

My colleague and I never programmed the engine management system to
create a delay between opening the throttle and increasing the
torque at the wheels. We aimed to maximise engine response, so I
disagree with the reported comments of Peter Taylor. Transient
vehicle response is a complex subject and influenced by many
factors including engine volumetric efficiency against
speed,throttled volume, powertrain inertia and torque converter
stiffness. I’m sorry it wasn’t better than it was, but we did our
best, and certainly didn’t try to limit it.–
Andy Stodart - 1995 & 1996 man XJRs and ex-Jaguar engineer
Northampton, United Kingdom, United Kingdom
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php

No complaints from me Andy !

Regards,

Dean, 95XJR Sydney

My colleague and I never programmed the engine management system to create a
delay between opening the throttle and increasing the torque at the wheels.
We aimed to maximise engine response, so I disagree with the reported
comments of Peter Taylor. Transient vehicle response is a complex subject
and influenced by many factors including engine volumetric efficiency
against speed,throttled volume, powertrain inertia and torque converter
stiffness. I’m sorry it wasn’t better than it was, but we did our best, and
certainly didn’t try to limit it.–
Andy Stodart - 1995 & 1996 man XJRs and ex-Jaguar engineer Northampton,
United Kingdom, United Kingdom --Posted using Jag-lovers JagFORUM
[forums.jag-lovers.org]-- --Support Jag-lovers - Donate at
http://www.jag-lovers.org/donate04.php

Not quite the same issue as was previously discussed but I notice that’s I am getting a delayed response from the throttle on my ‘99 XJR
This isn’t happening all the time but after a while driving I can increase pressure on the throttle pedal and nothing responds then its all on if I’ve gone too far. Seems to be less of an issue when using cruise control.
I have changed TB with a second hand item and the problem still persists.
No fault codes showing when I do a generic scan. I have the occasional orange warning light on the dash but cannot feel any difference with the performance. This comes up as ‘Failsafe’ ‘Engine Mode’
Would a transmission fault cause this?

One of the things that I love about the XJ8 is the instant throttle response. I’ve had 3 and all were the same so maybe you guys are just unlucky :frowning: