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MaseratiForumTechnical TalkTechnical LibraryAll Maserati Models3200GT / Assetto Corsa Throttle pedal pot quick modification

Throttle pedal pot quick modification

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26/10/2010 20:02:54  
AD

Posts: 120
Since: 9/8/2009
Status: offline 		Because of boomerang's (Luuk) research there is possible an easy modification to the throttle pedal pot

Thankyou to Luuk (boomerang) for the information below-

The cheapest fix: Connect the white and yellow wires near the connector to each other.

The white and yellow wires:

These are two sensor wires from the two integrated Potentiometers inside the Throttle Pedal Potentiometer.

If the readings of the two sensor wires differ too much, the ECU will bring the car in limp mode for "safety reasons".

I had that once, overtaking a lorry, driving between two other cars at 130 KM/H!

VERY DANGEROUS action from that ECU in those circumstances!

If you link the two sensor wires to each other, there will never be different inputs to the ECU anymore bringing the ECU to go in limp mode.

A Maserati specialist told me this "invention of mine" was a factory modification later on, because they too agreed this "safety thing" backfired sometimes in a very bad way!

Hope I was able to explain, otherwise please comment.

Of course any good garage should be able to connect the two wires, but if you want to give your Pedal Pot a real good second life, you should open, clean the vital parts inside and set up the Pedal Pot circuit board properly.

(No throttle 475Mvolt, full throttle 3300M volt)

But again, connecting the two wires is quite an improvement already.

Don't forget to spray the connector with a good contact cleaner.

I would really do the Pedal Pot while waiting for the TB conversion. There is a good chance that your Pedal Pot is making just as much trouble as your TB itself. At least make the connection between the white and yellow wires, it can be done at the wire loom outside the Pedal Pot near the connector too.

Don't forget to spray the contacts of the connector with a good contact cleaner.

You can leave the Pedal Pot in its place in that way.

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

boomerang



Extra thankyou to member cowsurgeon for the extra info below:

Following on from Luuk's advice on at least connecting the white and yellow wires (even if you don't strip down and clean the whole unit as he shows) I have done a pictorial guide to help folks do it themselves!

Thanks to boomerang and NickP whose advice helped persuaded me to get this done.

I used an allen key, a small screwdriver and a pair of wire snips.

Step 1:

Locate the Throttle Pedal Potentiometer to the right of the accelerator pedal:




Step 2:

Undo the screw holding the connector to the Potentiometer with an allen key:




Step 3:

Locate the wire to the connector in its clip and release it to give yourself more wire to work with:

Wire in the clip:-




Wire disconnected from clip:-




Step 4:

Slide the plastic cover on the wires away from the connector towards the Potentiometer to free the wires close to the connecor:




Step 5:

Disconnect the connector itself:




Step 6:

Cut the yellow and white wires:




Step 7:

Strip the four wire ends:




Step 8:

Twist the yellow and white wires together:




Step 9:

Connect the wires using a terminal connector:




Step 10:

Put everything back together!




Just to update, I have now soldered and covered this joint with heat shrink, which was a b*tch to do in situ. I would advise taking the Pedal Pot out if you fancy doing this ... I wish I had!!!

cowsurgeon

Attachment (11)

< Message edited by AD -- 26/10/2010 20:20:27 >

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Tension Not. Stay Positive
27/10/2010 8:50:54  
 

Posts: 91
Since: 20/7/2010
Region: Bath
Status: offline 		Thanks for the info and the great pictures.  Can I just clarify, is this just for the 3200?  What's the purpose of the wires in the throttle setup?  Would you recommend we do this even if we have no problems as yet??

Many thanks

Tristan
7/11/2010 14:11:13  

Posts: 775
Since: 19/8/2007
Status: offline 		Just to add some balance to this thread, twin circuits were specified to prevent a runaway engine, out of control with the throttles stuck wide open. If you do not consider that poses a very substantial safety risk with 370 bhp, I do not know what does.

IMO, this is nothing more than a bodge to avoid rectifying what would otherwise cost money to fix properly and for that reason I am amazed the Admin has decided to put the post in the Technical Library. Why not disconnect the oil guage, remove the ABS/ESR warning lights and permenently disconnect the traction control while you are at it

hope this helps

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You can lead a horse to water but you cannot force it to drink
18/12/2010 13:19:42  

Posts: 77
Since: 13/10/2009
Region: Newcastle upon Tyne
Status: offline 		Given that this is a saftey issue, I have to admit I didn't know this - so be aware - anyone following the above advice does so entirely at their own risk. Best to get a specialist to advise I think...I will be!

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Chris
17/1/2011 13:31:34  

Posts: 242
Since: 13/5/2008
Region: Holland
Status: offline

Without proper explanation from people who think this mod is dangerous, i think all of those warnings are just a matter of a bad feeling or extra precaution.
Did they really dig into this matter deep enough, 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 a BIG warning 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 people who are sceptical.

(On the other forum one could also read relevant reactions on this topic.) 
6/3/2011 11:20:42  

Posts: 775
Since: 19/8/2007
Status: offline 		I have just caught up with your reply Luuk and really must point out the significant danger here.

The fact is that the factory specified 2 circuits for safety reasons precisely for the reasons I have stated above. As you know, both circuits are independent from pedal potentiometer through to the DBW throttle body. Each circuit is dynamically tested against the other to determine if there is any difference - If this difference exceeds a predetermined (by the Factory) threshold, the DBW system gose into a failsafe setting i.e. what we refer to as "Limp mode".

If you defeat this by joining the 2 circuits, you have successfully removed a key safety device. With respect, it is not sufficient to say that a WOT (wide open throttle)  cannot happen where the the pedal pot has worn. There are some folk who will carry out your mod as a preventative precaution because they think this has been recommended and it most certainly is NOT.

Have you considered what could happen if the internals of the pedal pot have started to break up due to physical damage and a piece of detritus arcs causing full voltage to be applied? The result would be WOT with your mod but failsafe "limp" mode without. I have not done a full analysis but there is already sufficient doubt in my mind to warn against this mod in the strongest possible terms. Sorry Luuk, but this could kill someone and I do not want that on my conscience by remaining silent. The only exception, would be for diagnostic reasons and even then under tightly controlled conditions and with extreme care

hope this helps  

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You can lead a horse to water but you cannot force it to drink
27/3/2011 9:05:46  

Posts: 242
Since: 13/5/2008
Region: Holland
Status: offline 		If suddenly, for god knows what reason, the 5 volt supply would raise to say 8.7 volts, you would get a WOT.
If suddenly, ''''''''''''''''''''''''''''''''''''''''''''''''''''''''''', the potmeter ground would get high due to a bad common ground contact, you would get WOT.
If the full 5 volts would occur on the two sensor wires, caused by debrees as you state, yo would NOT get WOT, because if the outputvoltage of the sensorwires is getting higher then 3.7 volts, the ECU brings the car in limpmode again.

At this moment i have a 3200 in with the original and unopened pedalpot and the original throttlebody.
Customers complaint: Sometimes high/rising revs without touching the pedal!!
Very dangerous situations have occured allready, while the beloved redundancy system should have been active, with NO cel, NO limpodes!
This is not the first time that i heard of such a problem and it makes me even more sceptical about the whole safety system.

But in the interest of an eased mind for everybody, i would agree to use the "connected wire solution" as a diagnostic tool or as a temporary solution while waiting on a new pedalpot.
But again, in Holland there are driving quite a few 3200's with the connected wires, without any problems anymore, while these cars had some dangerous limpmodes on the highway before.
Everyone has to decide for himselve wich "safety system" he wants and in doubt, please buy a new pedalpot.

In the meantime we tested the new contactles pedalpot prototype on a car this weekend and it is going to stay there because of the very good results.
The contactless version has a dual output sensor, so the rdundancy system is "on" as some of us want it to.
Just look at the other topic on this forum for a picture of the converted prototype if you want.

Cheers.
31/3/2011 6:54:22  

Posts: 4
Since: 31/3/2011
Status: offline 		I like this solution but what others are there? I have replaced the potentiometer, both exhaust oxygen sensors and had vehicle looked at numerous times. Red light remains on although I've now had it disconnected and limp mode happens regularly especially after going over a bump? So what the options are there please?
13/4/2012 23:42:24  
 

Posts: 2
Since: 3/4/2012
Status: offline
quote:

ORIGINAL: cherbie I like this solution but what others are there? I have replaced the potentiometer, both exhaust oxygen sensors and had vehicle looked at numerous times. Red light remains on although I've now had it disconnected and limp mode happens regularly especially after going over a bump? So what the options are there please?
Perhaps your Knock Sensors ? Have you had full SD2/3 diagnostics yet ? Thanks
20/4/2012 13:16:13  

Posts: 777
Since: 20/9/2006
Region: Sheffield
Status: offline 		i would say it is the Accelerometer

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Maserati 3200GTA
Lexus IS 250 SE-L
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