THE 5000£ Question : tappet adjustment speed six

[engelborghs]

Hi all,

I just had my Tuscan (2005 MK2) serviced, clutch replaced and luckily decatted because the cats were broken. My dealer said that it took him quite some time to adjust the tappets but when I drove the car out of the garage it ran like never before. Impressive throttle response and much more responsive in the low rev range - I think the way a speed six should rev. To cut this story short addictive mind blowing and scary again...... but only 1 week after service this smooth and immediate response is sadly gone again. Why Why Why


In my opinion I had this issue from the beginning because when she was new that particular throttle response was there and disappeared after some 5000 miles. (Current mileage is 20000)

So THE 5000£ question is : What other causes are possible to explain this phenomenon apart from an upcoming re..re..rebuild? Sik

Upcoming/developing engine failure is maybe not the cause since it presented itself from the beginning.

Some tips: no other immediate signs of engine failure; oil use, blue smoke etc.....
acceleration is still good (followed a 911 turbo previous model effortless with throttle-anticipation
engine sounds less smoothly and notably different
it's not decat related I think
after service in the current weather condition full throttle was a borderline risk and scary, traction was easily lost which is not the case anymore at the moment, engine again lazy - like before

Please give me some other causes

A happy TVR year

Koen

Edited by engelborghs on Wednesday 2nd January 22:17

[rev-erend]

Throttle body problems ?

[heightswitch]

engelborghs said:

Hi all,

I just had my Tuscan (2005 MK2) serviced, clutch replaced and luckily decatted because the cats were broken. My dealer said that it took him quite some time to adjust the tappets but when I drove the car out of the garage it ran like never before. Impressive throttle response and much more responsive in the low rev range - I think the way a speed six should rev. To cut this story short addictive mind blowing and scary again...... but only 1 week after service this smooth and immediate response is sadly gone again. Why Why Why


In my opinion I had this issue from the beginning because when she was new that particular throttle response was there and disappeared after some 5000 miles. (Current mileage is 20000)

So THE 5000£ question is : What other causes are possible to explain this phenomenon apart from an upcoming re..re..rebuild? Sik

Upcoming/developing engine failure is maybe not the cause since it presented itself from the beginning.

Some tips: no other immediate signs of engine failure; oil use, blue smoke etc.....
acceleration is still good (followed a 911 turbo previous model effortless with throttle-anticipation
engine sounds less smoothly and notably different
it's not decat related I think
after service in the current weather condition full throttle was a borderline risk and scary, traction was easily lost which is not the case anymore at the moment, engine again lazy - like before

Please give me some other causes

A happy TVR year

Koen

Edited by engelborghs on Wednesday 2nd January 22:17

Why not remove your rocker cover and check the valve clearances?

If the valve is receeding into the head as is known on this engine then the valve clearance will close up. The engine tightens, extra load placed on the followers, the followers go bang and the engine catastrophically destructs. if you had a shimming job then this may have opened up clearances which through further valve recession are closing up again.

Then again you may just be paranoid because of the engine reputation.

If the issue is just general smooth running and lack of power then are you sure you dont just have a fuel / management / ignition problem

[engelborghs]

I'm not that paranoid because the difference is huge, that's why I want it back.
It's certainly not a fuel problem.

In your explanation - I'm no mechanic - can it be an on/off phenomenon? The same remark for the throttle body? no?

heightswitch said:

engelborghs said:

Hi all,

I just had my Tuscan (2005 MK2) serviced, clutch replaced and luckily decatted because the cats were broken. My dealer said that it took him quite some time to adjust the tappets but when I drove the car out of the garage it ran like never before. Impressive throttle response and much more responsive in the low rev range - I think the way a speed six should rev. To cut this story short addictive mind blowing and scary again...... but only 1 week after service this smooth and immediate response is sadly gone again. Why Why Why


In my opinion I had this issue from the beginning because when she was new that particular throttle response was there and disappeared after some 5000 miles. (Current mileage is 20000)

So THE 5000£ question is : What other causes are possible to explain this phenomenon apart from an upcoming re..re..rebuild? Sik

Upcoming/developing engine failure is maybe not the cause since it presented itself from the beginning.

Some tips: no other immediate signs of engine failure; oil use, blue smoke etc.....
acceleration is still good (followed a 911 turbo previous model effortless with throttle-anticipation
engine sounds less smoothly and notably different
it's not decat related I think
after service in the current weather condition full throttle was a borderline risk and scary, traction was easily lost which is not the case anymore at the moment, engine again lazy - like before

Please give me some other causes

A happy TVR year

Koen

Edited by engelborghs on Wednesday 2nd January 22:17

Why not remove your rocker cover and check the valve clearances?

If the valve is receeding into the head as is known on this engine then the valve clearance will close up. The engine tightens, extra load placed on the followers, the followers go bang and the engine catastrophically destructs. if you had a shimming job then this may have opened up clearances which through further valve recession are closing up again.

Then again you may just be paranoid because of the engine reputation.

If the issue is just general smooth running and lack of power then are you sure you dont just have a fuel / management / ignition problem

Edited by engelborghs on Thursday 3rd January 21:21

[Bitter'n'Twisted]

rev-erend said:

Throttle body problems ?

That's what I thought.
If those are not right, then any amount of tweaking by your mechanic will go
by the by almost straight away.
I had a similar problem until mine were 're-done' under warranty by TVR. (About 3 1/2 years ago).
But I'm no mechanic and I guess there could be several explanations.

[Buffoon]

Throttle Bodies. Adaptives on ecu are needing to be constantly reset by dealer to do a temporary job IMHO. Need to get the car along to Trackcar or some equivalent expert in field

[engelborghs]

Bitter'n'Twisted said:

rev-erend said:

Throttle body problems ?

That's what I thought.
If those are not right, then any amount of tweaking by your mechanic will go
by the by almost straight away.
I had a similar problem until mine were 're-done' under warranty by TVR. (About 3 1/2 years ago).
But I'm no mechanic and I guess there could be several explanations.

Throttle Bodies : stupid question but where are they located? Major Job? So expensive? Is there a way to test It? Probably not!

[NCE 61]

Throttle bodies





The "bushings" tend to wear over time & the throttle balance goes out quicker with more wear, hence it felt ok after the service. Could also be the throttle pots which tell the ECU the throttle position although this can be diagnosed by the diagnostic software.

[rev-erend]

I only mentioned it - as it's quite a common problem and results in rough running. As do the spark plug leads when they break down.

[Bitter'n'Twisted]

engelborghs said:

Bitter'n'Twisted said:

rev-erend said:

Throttle body problems ?

That's what I thought.
If those are not right, then any amount of tweaking by your mechanic will go
by the by almost straight away.
I had a similar problem until mine were 're-done' under warranty by TVR. (About 3 1/2 years ago).
But I'm no mechanic and I guess there could be several explanations.

Throttle Bodies : stupid question but where are they located? Major Job? So expensive? Is there a way to test It? Probably not!

You can get improved throttle bodies now. With bearings instead of whatever they were.
Heard very good reports about them on here.
I'm sure someone will come along and let you know more. Like where to get them for instance.
I don't think they're exactly cheap, but certainly nowhere near £5000! Talking a few hundred at a guess.

[Bitter'n'Twisted]

Forgot to mention. I think yours being a 2005 Tuscan might have the throttle bodies with bearings
rather than the earlier type anyway.

Doesn't mean they're working properly though, but may mean a cheaper (ie reconditioning) solution.

[so called]

In searching for a throttle body upgrade thread, I came across this one.
I dont know if engelborghs sorted out his problem but I am in the process of sorting a similar problem.

As mentioned, wear in the throttle bodies results in a very quick loss of tuning.
My 2000 Tuscan is now with Str8Six and is having the throttle bodies upgraded.
In the older speed six engine, the stainless steel shaft runs through the aluminium throttle bodies without bushings.
This results in wear and considerable play, resulting in tuning being lost and that the engine becomes a lot noisier due to throttle flaps constantly moving.
My Tuscan has done 80k miles and has considerable wear in the throttle bodies.
The upgrade I am having has the bodies bored out to allow roller bearings to be pressed in and so, hopefully a long lasting and reliable fix which should provide great benefit to the engine.
Cant wait to get her back and see what the difference is.

Has anyone else had this upgrade and can they please advise me on the results.

Thanks,
Tony.