Full Throttle reset not working...any idea's?

Robbe

Junior Member
Messages
87
Hi All,
my 3200 (manual) has been throttle sensitive since I bought it.
As I already have a Sacer cap on the throttle body, I can safely assume that I have a contactless Throttle Body.
So I tried the reset procedure (2 min idle position with ignition on, shut off, then 12 seconds Full throttle , you probably know the procedure)
But it did not make a difference, so I suspected the Pedal Pot.
I joined the yellow and white wire (yes I know :) ) and it made a slight improvement. So I was convinced the PP was on its way out.
I bit the bullet and bought one of Dave's contactless PP.
I installed it, voltage output now nicely between 0.4V and 3.27V, so that is doing what it should do it seems.

But: the reset procedure does not seem to help. Idle position is good (as it was), but the pedal is more nervous than ever.
4 mm of pedal travel (0.6V output) lets the car rev to 4000 rpm, so it is really nervous.

Dave is really helpful in trying to find what is wrong, but so far we ( I at least) have run out of ideas.
It looks like the FT reset has no effect, have done it 6 times now, for 12 seconds (not 5) to be on the safe side. But no result.
So the reset thing looks to be not working. Anybody heard of that before, and knows what to do now?

I do not have access to a SD , and the nearest specialist is probably over an hour's drive from me, so I am really looking for things to check myself before I have to give up and try to book an appointment with one of the 2 or 3 specialists in the country (Netherlands)
 

Contigo

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18,376
I assume you reversed the Pedal Pot yellow and white wire mod since installing the pedal sensor from Davy? (It may not make any difference as there may only be one circuit in his application)

I would try adjusting the actual accelerator pedal itself and also make sure the pedal sensor is mounted securely with the two allen key bolts being done up extra tight.

What voltages does it jump from/to when applying the 4mm of travel? Is it a nice linear jump in volts from the 0.4V to 3.2V as the pedal travels slowly? I would clean the contacts too with a small brush and some electrical contact cleaner.
 

Robbe

Junior Member
Messages
87
Thanks for your answer.
The pedal pot from Dave is brand new (no contacts to clean I guess), and the yellow and white wires I joined before were in the loom of the factory PP, so with the new PP wires are not joined.
I had already adjusted the pedal stops and the PP sensor itself (Dave's PP has this facility!) to get those correct voltages.

The voltage output is linear, from 0.4 up all the way up to 3.27 (below the upper threshold of 3.3V). So the PP output voltage is as per Works manual.
At 4mm of travel output is like 0.8V. Sounds normal to me.
But the reaction of the engine is not linear at all: while 4 mm pedal gives 0.8V (so output really low like it should) , in neutral (manual) that is enough to jump to 4000 rpm...
And that puzzles me as it makes the car almost undriveable.
So:
- Output is correct, within range at every point
- PP is contactless
- TB is contactless (assumption it is because of the Secer cap)
- reset of throttle has been carried out 7 times now, FT time 5 sec, 6 times 12 seconds. So that should have done the trick you would think.

Still the engine reacts like FT is at 1 cm pedal travel...
 

Contigo

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Messages
18,376
A Sacer cap to me shouts of "I've bought the end caps off Ebay and had a go myself!"
 

Contigo

Sponsor
Messages
18,376
Thanks for your answer.
The pedal pot from Dave is brand new (no contacts to clean I guess), and the yellow and white wires I joined before were in the loom of the factory PP, so with the new PP wires are not joined.
I had already adjusted the pedal stops and the PP sensor itself (Dave's PP has this facility!) to get those correct voltages.

The voltage output is linear, from 0.4 up all the way up to 3.27 (below the upper threshold of 3.3V). So the PP output voltage is as per Works manual.
At 4mm of travel output is like 0.8V. Sounds normal to me.
But the reaction of the engine is not linear at all: while 4 mm pedal gives 0.8V (so output really low like it should) , in neutral (manual) that is enough to jump to 4000 rpm...
And that puzzles me as it makes the car almost undriveable.
So:
- Output is correct, within range at every point
- PP is contactless
- TB is contactless (assumption it is because of the Secer cap)
- reset of throttle has been carried out 7 times now, FT time 5 sec, 6 times 12 seconds. So that should have done the trick you would think.

Still the engine reacts like FT is at 1 cm pedal travel...

The Voltages are fine, all the PP does it send that voltage to the ECU which then sends it to the Throttle body dictating the opening of the butterfly. It's 99.9% likely to be the TB itself. You could try removing the inlet and checking the movement of the butterfly by hand to see how much resistance there is etc.... The other parts which fail consistently are the carbon tracks themselves which dictate butterfly position, it's more than likely these carbon tracks which are worn and causing problems. As Catman says don't assume the Throttle Body has been upgraded to contactless by a reliable source too.
 

Robbe

Junior Member
Messages
87
As the PP output is measured and completely within range (0.35 - 3.3V being the range afaik) , the only other components are ECU and TB.
So one of these must be the culprit. As the ECU has no bad rep and the TB has, I am leaning towards that one too.

But with the old PP (with joined wires) it was better, so I still do not see how a new PP would affect the TB.
Or is it possible that the old full throttle output was like 1.5V instead of 3.3V, and that such a low voltage communicated better with the TB?
With my LHD car the PP is more difficult to remove, otherwise I would install the old PP to measure the voltage now...
Maybe tomorrow if I have a little spare time left I can have a try at it. Would probably shed some light on it.

About the sacer cap, is it possible to fit one of those without installing the internal magnet, and in fact use the old tracks and wiring?
Or does the old Magneti cap has a function? And a hybrid form therefore is not possible?
 

Robbe

Junior Member
Messages
87
I looked at some youtube video's from the Volvo version of the TB, and how to install a contactless system.
Looks very easy actually, as long as you are patient with cleaning the pins inside.
Is the 3200 TB the same in that respect?
If so, I understand that a previous owner did it himself. And there is not much that can go wrong it seems.
 

Contigo

Sponsor
Messages
18,376
It's not the same TB mate as the Volvo, similar but different.

The things need calibrating properly.
 

Robbe

Junior Member
Messages
87
The default throttle position needs to be set, I understand, by twisting the magnet just a little until optimum is reached. With the Volvo that is 1.35V I read
But other adjustments to calibrate it properly can't be made as far as I understand...
There is a very well written article (by an engineer) on the net about this, not sure if I am allowed to post a link?
 

allandwf

Member
Messages
10,958
I'm sure I've seen that article, when I too looked into the Volvo TB. They have just the same issues as us. I'm sure link will be ok, after all more knowledge the better. Mine has a contactless TB, (from Maserati Shed,) and Davys Pedal Pot mod. Have given no issues since. No doubt they will at some point as they are still moving parts, just less components to fail, but a lot less temperamental.
 

davy83

Member
Messages
2,809
Robbe tried measuring the rpm the engine developed at different pedal sensor voltages and I wondered what my car would do just idling, so i measured it. I thought this might help anyone else trying to make sense of a throttle problem


I got this

RPM 1100 1600 2500 3500 4200

VOLTS .450 .565 0.680 .720 0.780
 

boomerang

Member
Messages
412
Just send your TB to one of your U.K. Specialists for examination.
Fiddling around with a TB, can ruin the electronic module inside the TB easily.
And the Maserati TB differs more from the Volvo units then you may expect, there's also more to it, then just mounting the magnet in its correct position.
 

Robbe

Junior Member
Messages
87
Maybe the problem is with the TB and not the PP, I do not know.
The PP (one of Dave's) is giving decent voltage values, so I assume the PP is not the problem.
Only thing is that with the old PP it was less nervous than it is now. But maybe that one only had a range of 0.4 - 1.5V or so...
When the weather is a little better, I will switch the PP back to measure.
Boomerang, are you still in business with the TB's? I rather keep it in Holland than send it abroad when it turns out to be necessary to have it checked...
 

Robbe

Junior Member
Messages
87
Almost a year later, and the unit finally gives real problems.
After getting CEL for almost a week, which would go away after restarting, the CEL was there to stay. With ignition ON it was already there.
Unfortunately I still can't read any codes with all 3 of my readers (2000 year car with wide OBD2 connector but OBD system), but as last month the car started to get more nervous than ever, I assumed it is the ETB system.
As the voltage of the pedal side (Dave's contactless unit) is nicely within its range, the culprit had to be the ETB.

So I removed it from the car, to discover that the butterfly valve was almost stuck, and could only be moved while making a terrible crunching noise.
I removed all three covers, and on the magnet side (the "Original" side) I found lots of metal grit/grindings which was the upper layer of the magnet that had come apart. It was that much, that it connected the magnet to the copper windings.
See picture below.
ETB1.jpg

After cleaning it, and putting all together again, the butterfly valve went smooth again: time to test on the car. Ignition ON.
No difference, immediately a CEL.
According to the Volvo info, default voltage should be 1.35V between pin 1 and 3 on the sacer side of the unit.
I measured, and mine was 1.2V. Opening up again and turning the sacer magnet gave 1.3V.
Now with ignition ON the CEL is gone, but when starting the car it directly is back and the car won't go beyond 1500 rpm. So not even decent limp home.

Extra info: I remember the unit making a high pitched sound before, which it does not do now.
I can see the valve moving to fully shut and slightly open again on turning the ignition ON. So the Motor inside the ETB is working (a bit at least).

Does anybody have info on this?
- what should the voltage be on pin 1 and 3 on the 3 pin side on default (ignition ON, engine not running)? 1.35V for Volvo, and raising it from 1.2V to 1.3V did help a bit, but is it enough?
- should the unit make a high pitched sound? Now it does not, but it has done that in the past.
- does the electromotor magnet of the picture really need that shiny layer? I believe it is aluminium, so not magnetic. Now it is completely gone, does that affect the electromotor?
- on startup, is the small movement from slightly open to shut to slightly open the full test? Or should the valve move a lot more in the initializing test?

Thanks in advance!
 

davy83

Member
Messages
2,809
Does the butterfly valve move smoothly when you press it with your fingers and does it spring back into the idle position smoothly? I have not had to mess around with the TB on my car much but I believe it should move smoothly. Some one else will no doubt jump in here.
 

Robbe

Junior Member
Messages
87
Hi Dave, before I took the TB off, it made a crunching sound when I turned the ignition on. And when I had the TB in hand , movement was far from smooth, it was terrible.
Otherwise I would not have opened it, I am more of solving mechanical issues than electronics...
After cleaning the big magnet in the picture, the movement is smooth again.
I initially thought that the extra resistance that the magnet got from the debris had caused the problems with the CEL (the valve not quite doing what the computer told it, hence wrong voltage feedback, and thus a CEL)
But even if that might be the case, it has not helped since I still have the CEL and can't go beyond 1500 rpm.

In the mean time I have bought a Volvo TB (what they call ETM on Volvo forums), and managed to connect that one to the car. Wire colors are the same, only the connector is different.
The important voltage is 1.43 on this Volvo one, so excellent.
But still a CEL and a max of 1500 RPM....I had hoped it would at lease function , even if not optimal. but alas...

At least I now know that a TB does make a high pitched sound on initializing.
Any ideas if that sound comes from the electronic board which I want to switch, or from the DC motor?
Because if it is the motor, then I can switch the boards and have a singing maserati TB again, and that might be what is needed (not the actual singing of course, but the action that causes it)
Thanks!
 

Tamariini

Junior Member
Messages
102
Hi Dave, before I took the TB off, it made a crunching sound when I turned the ignition on. And when I had the TB in hand , movement was far from smooth, it was terrible.
Otherwise I would not have opened it, I am more of solving mechanical issues than electronics...
After cleaning the big magnet in the picture, the movement is smooth again.
I initially thought that the extra resistance that the magnet got from the debris had caused the problems with the CEL (the valve not quite doing what the computer told it, hence wrong voltage feedback, and thus a CEL)
But even if that might be the case, it has not helped since I still have the CEL and can't go beyond 1500 rpm.

In the mean time I have bought a Volvo TB (what they call ETM on Volvo forums), and managed to connect that one to the car. Wire colors are the same, only the connector is different.
The important voltage is 1.43 on this Volvo one, so excellent.
But still a CEL and a max of 1500 RPM....I had hoped it would at lease function , even if not optimal. but alas...

At least I now know that a TB does make a high pitched sound on initializing.
Any ideas if that sound comes from the electronic board which I want to switch, or from the DC motor?
Because if it is the motor, then I can switch the boards and have a singing maserati TB again, and that might be what is needed (not the actual singing of course, but the action that causes it)
Thanks!
were you able to sort this out? Mine did exactly the same and now i need the voltage to which Sacer unit should be set.