Discussion
In third when I hit top revs just before the lights coming on the car jults as though I am releasing the peddle slightly and then re applying but I'm not. A friend has asked if its go varible timing and may be adjusting it self??? When I change into four at say 110mph its fine again,
any ideas oh wisemen?
any ideas oh wisemen?
sounds like some kind of misfire to me
could be anything ignition-wise, whether on electrical, fuelling or mechanical side of things
I don't know the Tuscan's idiosyncracies so hopefully it's just a small and common fault that's easily fixed
generally speaking, a misfire right at the top end you can drive through sounds electrical, ie leads are arcing out or coils are not up to the job - check those first
is the engine noisy at idle etc? If it is the famous follower problem your valves will not be opening properly and this will manifest itself as a problem at high revs (as inlet and exhaust characteristics won't be correct)
could be anything ignition-wise, whether on electrical, fuelling or mechanical side of things
I don't know the Tuscan's idiosyncracies so hopefully it's just a small and common fault that's easily fixed
generally speaking, a misfire right at the top end you can drive through sounds electrical, ie leads are arcing out or coils are not up to the job - check those first
is the engine noisy at idle etc? If it is the famous follower problem your valves will not be opening properly and this will manifest itself as a problem at high revs (as inlet and exhaust characteristics won't be correct)
Mine does the same, although until reading your posts I was only half sure it does it! It doesn't always do it but when it does it is round the green/amber light time and I'm always on the brink of changing gear anyway so I've been trying to convince myself that it's happening as I lift off the accelerator, rather than just before! I don't know why it does it, but I've only had the car 3 weeks and it's just been taken away on a low loader 
because the oil light has recently started coming on at high revs. The car seems to drive beautifully, but I'm having it checked out just to be safe! I don't know if the problems are related.
because the oil light has recently started coming on at high revs. The car seems to drive beautifully, but I'm having it checked out just to be safe! I don't know if the problems are related.quote:
Mine does the same, although until reading your posts I was only half sure it does it! It doesn't always do it but when it does it is round the green/amber light time and I'm always on the brink of changing gear anyway so I've been trying to convince myself that it's happening as I lift off the accelerator, rather than just before! I don't know why it does it, but I've only had the car 3 weeks and it's just been taken away on a low loader
yep, exactley the same light and is it me??? thought the very same. Are you going to ask your dealer if so it'll save me a fairly long drive to mine.
Thanks
Here goes, apologies if I get any of the finer details incorrect:
This "Judder,Hesitation etc" is a niggle that effects some cars in varying degrees. It IS easily fixed!
First the cause -
When you rev through about 6000rpm the throttle potentiometer occasionaly gives a false full throttle opening. The reaction of the ecu is to open the injectors more to give the engine more fuel for the initial aceleration (like the old fuel squirts on carbs). As the engine is already at full throttle and running the injectors at 93% capacity the extra opening demand tries to push the injectors past 100%, the ecu then realises it can't do that and thus cuts that injector for a millisecound - result no fuel through that injector and hence the effect of a "judder, hesitation or in bad cases rev limiter like symptoms"
As the false reading is caused by electro, electromechanical interferrance with the pot and sometimes the ecu it's effect varys dependant on car condition, engine tune, climate etc etc etc.
The solution -
A "dethrottled" chip is avaliable from the dealer normaly on an exchange basis and normaly foc. This chip has a lengthened throttle pot sampling time so it averages out the erroneous spike of info thus not allowing the injectors to be requested over 100% thus no problems.
This chip normaly resolves the problem instantly and all dealers should be aware of the problem and be able to diagnoise accordingly. Some of the independants may not yet be fully up on the problem.
My car has a dethrottled chip and is fine, I swapped it back to a std chip last night and my judder came straight back!
I cannot stress again but speak to your dealers and they should easily swap the chip at your next service. If they prove unhelpful ring the factory service dept who are aware of the issue.
Hope this helps.
>> Edited by fish on Thursday 21st February 13:29
This "Judder,Hesitation etc" is a niggle that effects some cars in varying degrees. It IS easily fixed!
First the cause -
When you rev through about 6000rpm the throttle potentiometer occasionaly gives a false full throttle opening. The reaction of the ecu is to open the injectors more to give the engine more fuel for the initial aceleration (like the old fuel squirts on carbs). As the engine is already at full throttle and running the injectors at 93% capacity the extra opening demand tries to push the injectors past 100%, the ecu then realises it can't do that and thus cuts that injector for a millisecound - result no fuel through that injector and hence the effect of a "judder, hesitation or in bad cases rev limiter like symptoms"
As the false reading is caused by electro, electromechanical interferrance with the pot and sometimes the ecu it's effect varys dependant on car condition, engine tune, climate etc etc etc.
The solution -
A "dethrottled" chip is avaliable from the dealer normaly on an exchange basis and normaly foc. This chip has a lengthened throttle pot sampling time so it averages out the erroneous spike of info thus not allowing the injectors to be requested over 100% thus no problems.
This chip normaly resolves the problem instantly and all dealers should be aware of the problem and be able to diagnoise accordingly. Some of the independants may not yet be fully up on the problem.
My car has a dethrottled chip and is fine, I swapped it back to a std chip last night and my judder came straight back!
I cannot stress again but speak to your dealers and they should easily swap the chip at your next service. If they prove unhelpful ring the factory service dept who are aware of the issue.
Hope this helps.
>> Edited by fish on Thursday 21st February 13:29
quote:
A "dethrottled" chip is avaliable from the dealer normaly on an exchange basis and normaly foc. This chip has a lengthened throttle pot sampling time so it averages out the erroneous spike of info thus not allowing the injectors to be requested over 100% thus no problems.
Sounds like a bodge that will reduce throttle response - the ECU uses the rate of change of ECU to work out how much acceleration enrichment to use. Why don't they just fix the actual cause, i.e. the noisy pot or bad wiring?
danny
>> Edited by dannylt on Friday 22 February 09:25
Are you saying that the solution to the problem is detuning the tuscan? The term "dethrottled chip" certainly suggests that.
I would be very interested to know if this is true, and if it is, what the true standard 4 ltr performance figures really are, with and without the dethrottled chip.
I would be very interested to know if this is true, and if it is, what the true standard 4 ltr performance figures really are, with and without the dethrottled chip.
Maybe the use of the term dethrottled is a little misleading. It does not effect the performance at all. It just changes the way the ecu uses the throttle pot inputs very slightly. There is no real noticeable difference between the two chips. I've used both and I can't tell anything.
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