Think i have diagnosed my poor running!
Discussion
I have certainly identified a problem, even if it isnt the whole problem. Getting poor running after Str8 six having only set the car up 300 miles or so ago. Have done a simple ignition system check and it ll appears to be OK, so took a closer look at the throttle bodies.
I get 1.8% movement on the spindle at the T2 end, and 2.6% on the T1 end, so the range they can be out is quite significant. I also found that once running, the chink i could hear (that i thought was engine) was actually a throttle butterfly rattling in the body at the T1 end, put my finger on it and it stopped!!! (it is screwed in tight - i checked them all!). Can change the note of the engine from quite lovely to really horrible and lumpy with finger movement of the throttle spindles.
Put the synchrometer on and i get a change in airflow of 50% - so i would say that, combined with the throttle pot % changes - is causing my crappy running, and was probably causing the high end hesitation before the rebuild. They didnt seem too bad when having the rebuild done, i wish i had just got it done!!
A job to now get done then....throttle bearing mod. I am getting a little fed up that i have had to do much this year already!! (well, since buying - not since 11 days ago!)
Hope the info helps others suffering with poor running and hesitation!
Rob
I get 1.8% movement on the spindle at the T2 end, and 2.6% on the T1 end, so the range they can be out is quite significant. I also found that once running, the chink i could hear (that i thought was engine) was actually a throttle butterfly rattling in the body at the T1 end, put my finger on it and it stopped!!! (it is screwed in tight - i checked them all!). Can change the note of the engine from quite lovely to really horrible and lumpy with finger movement of the throttle spindles.
Put the synchrometer on and i get a change in airflow of 50% - so i would say that, combined with the throttle pot % changes - is causing my crappy running, and was probably causing the high end hesitation before the rebuild. They didnt seem too bad when having the rebuild done, i wish i had just got it done!!
A job to now get done then....throttle bearing mod. I am getting a little fed up that i have had to do much this year already!! (well, since buying - not since 11 days ago!)
Hope the info helps others suffering with poor running and hesitation!
Rob
Edited by Robertjp on Monday 11th January 10:21
I can understand how this is getting you down. They can be a money pit, although it sounds like you should have a cracking car once this is last bit of work is done. In a few months when the sun comes out and you're whizzing along some country lanes it will all be forgotten. And another way to look at it is that you would have lost the same amount of money in depreciation if you had bought a Porsche from a dealer, it's just that it is more visible at the moment. Chin up.
Rob, you will be able to alter the running by pushing on the butterfly its self, each throttle has its own shaft and the linkage is moved by the individual balancing adjustment screws. In one direction they are only kept in sequence by the small linkage spring so the butterfly will move independently.
As for the throttle pot readings, are those readings with a laptop on? If so did you go for a drive and log the position results? Without doing that its hard to say what you are actually getting, as I doubt that its a case of adding the two readings you have and getting 4.4% difference. Have you tried resetting the throttle positions and adaptes and seeing if the poor running goes?
Oh i have dug those parts out but not had chance to post yet. Do you still want them?
As for the throttle pot readings, are those readings with a laptop on? If so did you go for a drive and log the position results? Without doing that its hard to say what you are actually getting, as I doubt that its a case of adding the two readings you have and getting 4.4% difference. Have you tried resetting the throttle positions and adaptes and seeing if the poor running goes?
Oh i have dug those parts out but not had chance to post yet. Do you still want them?
Edited by BGB autosport on Monday 11th January 12:30
BGB autosport said:
Rob, you will be able to alter the running by pushing on the butterfly its self, each throttle has its own shaft and the linkage is moved by the individual balancing adjustment screws. In one direction they are only kept in sequence by the small linkage spring so the butterfly will move independently.
As for the throttle pot readings, are those readings with a laptop on? If so did you go for a drive and log the position results? Without doing that its hard to say what you are actually getting, as I doubt that its a case of adding the two readings you have and getting 4.4% difference. Have you tried resetting the throttle positions and adaptes and seeing if the poor running goes?
Oh i have dug those parts out but not had chance to post yet. Do you still want them?
I was going to email you when i got home tonight - no - i dont think i do thats BGB, the ignition system seems fine after some more thorough checks than i had done before. Thanks though it was appreciated. As for the throttle pot readings, are those readings with a laptop on? If so did you go for a drive and log the position results? Without doing that its hard to say what you are actually getting, as I doubt that its a case of adding the two readings you have and getting 4.4% difference. Have you tried resetting the throttle positions and adaptes and seeing if the poor running goes?
Oh i have dug those parts out but not had chance to post yet. Do you still want them?
Edited by BGB autosport on Monday 11th January 12:30
I was careful to try and assess only the 'slack' in the throttle body, without opening or closing the butterfly, the spindle itself you can 'click' laterally in its hole in the TB. In different positions laterally it changes the running quite significantly. The butterfly valve i only touched to see if it was the source of the 'chattering'...it sounded internal to the engine at first which was worrying! The chattering is the T1 end (blue throttle pot) where the movement is most significant - around 3%. It seems the internals of the throttle pots also wear.
This was with the laptop in my garage, i have tried driving too - and come back to a change of 4% one throttle pot to another.
In the end i rebalanced the TB's with a synchrometer and their individual adjuster springs, reset throttle pots and adaptive maps and she ran better. The trouble is with that amount of slack in the system it will only be a matter of time befoe things go pear shaped again!!
I had a similar problem on my year 2000 Tuscan Mk1.
On the early ones there were no bushes between the butterfly shafts and the aluminium throttle body castings.
Funnily enough it was Jason at Str8Six who upgraded my throttle bodies with roller bearings.
I think it cost a bit over 600 quid.
The car ran SO much better after that mod.
Understand what your saying about spending lots of money, I thought I had just about finished mechanically (was about to start on sorting out the interior) when I wrote her off.
Yes, it also reduced the bad noises considerably and left the good.
On the early ones there were no bushes between the butterfly shafts and the aluminium throttle body castings.
Funnily enough it was Jason at Str8Six who upgraded my throttle bodies with roller bearings.
I think it cost a bit over 600 quid.
The car ran SO much better after that mod.
Understand what your saying about spending lots of money, I thought I had just about finished mechanically (was about to start on sorting out the interior) when I wrote her off.
Yes, it also reduced the bad noises considerably and left the good.
Edited by so called on Monday 11th January 20:35
so called said:
I had a similar problem on my year 2000 Tuscan Mk1.
On the early ones there were no bushes between the butterfly shafts and the aluminium throttle body castings.
Funnily enough it was Jason at Str8Six who upgraded my throttle bodies with roller bearings.
I think it cost a bit over 600 quid.
The car ran SO much better after that mod.
Understand what your saying about spending lots of money, I thought I had just about finished mechanically (was about to start on sorting out the interior) when I wrote her off.
Yes, it also reduced the bad noises considerably and left the good.
Jason has offered, but my money pot is getting low and i would rather see if i can do myself or get someone local to do it for me, it isn't a job i would trust just anyone to do, but i have a place in mind. On the early ones there were no bushes between the butterfly shafts and the aluminium throttle body castings.
Funnily enough it was Jason at Str8Six who upgraded my throttle bodies with roller bearings.
I think it cost a bit over 600 quid.
The car ran SO much better after that mod.
Understand what your saying about spending lots of money, I thought I had just about finished mechanically (was about to start on sorting out the interior) when I wrote her off.
Yes, it also reduced the bad noises considerably and left the good.
Edited by so called on Monday 11th January 20:35
Edited by Robertjp on Tuesday 12th January 12:02
Some info i have gleaned from looking into this issue and how im going to solve it...
http://www.pistonheads.co.uk/gassing/topic.asp?h=0...
http://www.pistonheads.co.uk/gassing/topic.asp?h=0...
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