DONT forget the trottlePEDAL potentiometer!!!!

The mod was posted by Luuk/Boomerang who is, as far as I am concerned, the governor in this area.

I accept your runaway throttle problem, but surely, anyone with an ounce of common sense, would just dip the clutch and turn the engine off in the rare event this could happen.

I would just like to add, any mods you carry out are at your own risk, so its a fair point to add the open throttle thing.

I rang grimaldi to book my car in for jan and he told me he doesnt want to look at it with the limp mode off after we did with the soldering as its dangerous to test drive the car, told me it can be full throttle at any minute and i shouldnt drive it up there

Have to fix it then book it in........

A manual is better as you can use the clutch but i have an auto....need to be quick to move it to N

Without proper explanation from Grimaldy, i think all of those warnings are just a matter of a bad feeling or extra precaution.
Did they really go into this matter, did they research the complete circuitry and did the measure the internals of the pedalpot?
If they did, i would be glad to learn where i made a mistake in my conclusions of course.
The two potentiometers inside the housing are simply interupting when worn. (The resistortracks wear and resistormaterial is scratched slowly from the isolating layer.)
IMPORTANT: An interupted signal does NOT cause full throttle, but NO throttle, or limp mode!
Two parallel potentiometers (after the soldering mod) that would interupt at exactly the same (worn) spot of the resistortracks (chance is 1 on a million?) wil cause NO throttle, NOT FULL THROTTLE!
Therefore, the warning above is unnescesairy, because NO throttle is exactly what is going to happen with a worn UNMODIFIED pedal potentiometer in the first place.
Please let someone tell me what the problem of the mod IS then!?!
If BOTH tracks inside a modified pot are wearing further and further, even the two parallel resistortracks will get out of range, causing CEL and LIMPMODE just as an original one, forcing you to exchange the pedalpot finally.

Things would be totally different of course, if an interupted reading would cause FULL throttle, but that is NOT the case.
In that case the warning of Grimaldy would be wise and very relevant, but i would not ever have advised to do so in the first place!
Still: Exchanging the Pedalpot would be the best thing to do, that is where i would agree with Grimaldy.

Although I am a new owner and not overly familiar with the internals of the pedal potentiometer, the aircraft I fly have a fly by wire system that is very similar (also made by the Italians). I discussed this issue with our avionics engineers and unanimously the respond exactly the same as Luuk. A mismatch between values of two independent systems will result in either a null value returned (zero throttle) or to a predetermined default value (limp mode).

If both values are zero then it will return a zero value regardless of the default value, as the system will sense the Engine Control Unit (throttle) as being off.

The last thing the the designers would allow is a maximum value to be returned if one system was faulty and showed a mismatch in values, as in our case this would result in a Engine Control Unit runaway high-side (which is not possible in our aircraft). Similarly I don't believe that a system with a specific intent to ensure safe operation of the engine throttle would allow a maximum value to be the default.

Whilst the full throttle situation is probably possible under some circumstances, I am confident that the information that Luuk has provided and the feedback my engineers have given me is that the mod to join the potentiometers is NOT going to cause it. these systems are designed deliberately with a failsafe state of OFF and NOT a failsafe state of FULL ON.

I have carried out the mod after doing my own due diligence so please give my response as much or as little consideration as you see appropriate.


Neil

Interesting debate guys.........and good points of reference and expert knowledge.

P

Luuks fix worked for me and I am happy, the car now runs like a dream. In fact it was prior to the fix that the throttle had a life of its own and revvved high on its own, several times I had to turn it off at the ignition before it revved too high. Nigello posted this nonsense about it being dangerous on the other board a while back now...

Likewise it has worked for me too. I must say, the arguments above make sense, and Luuk's explanation of the extensive research into the pedalpot measurements he has done is very convincing, and my car has been running better since I made this change.

I only thought I'd post Nigelo's comments as he implied it was a safety issue,and as it was me who had posted the pics on the how to for this topic. I wanted to make sure that anyone who attempted it had as much info on the mod as possible, to allow them to make an informed decision before doing it themselves.

I also wanted to make sure that I'm not going to be implicated if something adverse happened as a result of someone doing it! As I said before I'm not an expert on electrics/electronics or in automotive engineering...

rotorheadcase said:

I have carried out the mod after doing my own due diligence so please give my response as much or as little consideration as you see appropriate.


Neil

Click to expand...

Although I never had any issues with Check Engine Lights coming on or so, I have also carried out this mod, just to prevent any issues happening in the future

boomerang said:

Well done Chris.
Maybe soldering later on for your safety?
Don't forget this little connection rules over nearly 400 HP!
Confronting if you think about it: 370HP are controlled by two tiny little wipers over two tiny and very vonurable resistortracks.............!!!

Click to expand...

Hi Luuk,

I have done this link and soldered as shown, the car is working fine and the tick over is just fine.

Before having by TB refurb by you late last year I had the car go into limp mode when travelling on the motorway was a complete pain in the backside.

Can you confirm that this little link ups the BHP to 400?

Paul L

i dont think so paul, i think he meant nearly 400bhp, could be wrong....

Interesting thread this. I went to do mine today and it appears that someone else has attempted it before. Only problem is that they have changed the cable colours too and there are just a combination of red and white!

Performed this today and replace rpm sensor. Car ran sweet for about an hour, full boost etc but then hit a slight kick in road and CEL came back on. Surelty It must be throttle body related?