Lets face it, the throttle on these engines sucks. I am not sure if its just the nature of turbodiesels to behave like this, but I find the acceleration under load of these engines to be incredibly unsteady and sensitive at times.

Perhaps some of you folks with 60x engines can advise me on whether it is worth the modification to a cabled throttle for the 61x turbo engines.

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Good luck.

And if you do get linear response to accelerator input somehow, please tell the rest of us.

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Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar.

83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 400,xxx miles
08 Suzuki GSX-R600 M4 Slip-on 22,xxx miles
88 Jaguar XJS V12 94,xxx miles. Work in progress.

I don't believe your problem is due to the design of the linkage. What, exactly, are you experiencing (sticking, hesitation, surging)? Have you lubricated the linkage? Is it adjusted so that full pedel travel moves the IP rack to the stop? The acceleration is not linear, but the fuel delivery should be steady.

skippy,

thats a reassuring reply.


You think the mechanical nature of the controls determines its response?

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I think it has more to do with tubo lag and then the turbo suddenly catching up. ALDA adjustment would speed spool-up, but then you'd get smoke, which you may not want.

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Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar.

83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 400,xxx miles
08 Suzuki GSX-R600 M4 Slip-on 22,xxx miles
88 Jaguar XJS V12 94,xxx miles. Work in progress.

its all moving very freely.

surging?... no more than the boost from turbo provides


I mostly drive avoiding boost (city limits), it always wants to accelerate or drop in rpm... never steady.

I have removed the play from the linkage

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I have turned it down for that reason to where lag is tolerable.

I am still under the impression that all the various pivots and ball joints provide a fantastically sloppy yet overly sensitive pedal-to-IP relationship.

ie.. you depress the pedal to point where resistance builds, then there is a very, very tiny window where alot of fueling occurs.

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While not as smooth as gassers I've driven, I've had good luck making throttle response smoother by doing the following:
-Lube and remove slack from throttle linkage, all of it
-Remove EGR vacuum mess, 3/2 valves, cruise control (if not working)- makes pedal action easier
-Adjust bowden cable for later shifts (often these cars want to shift right as it hits boost, giving a jerky feeling)
-Adjust ALDA so that engine recieves more fuel lower on the throttle curve, smoothing out the acceleration.

Also, make sure the transmission is receiving optimal vacuum. Harsh and jerky should not be used to describe these cars, and sometimes a superior shift kit is necessary to make the trans shift evenly across gears. But a lot can be done with vacuum and shift points.

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