355 Exhaust Bypass Valve Solenoid Wiring

Yes, when properly adjusted, the throttle linkage will hit a hard stop (making a clicking sound) when the plate is in the perfect vertical position (full opening). The eight independent throttle plates are synchronized so it is not advisable to go in there and start adjusting things without proper equipment.

 

I was going to suggest this same direction. Need to pull the cover and tank. Its a lot of work but you really need to get the top off to see it and get it to a good starting point. Plenums off even better but that is a LOT more work. I have mine off now since I pulled the injectors for cleaning. Was nice to visually inspect the throttle linkages clean the throttle plates etc. im about to do a full balance on them all. All the orings on the air needles and bleeders needed replacing. I found a plenum gasket that should be replaced. A worthwhile exercise.

 

I didn't realise you had an F1 car. Let's hope you don't have to replace it the TPS. They are expensive and rare, including the aftermarket ones. I was looking at this yesterday for an hour or two. I think the cheapest was around U$300

I don't even have a (confirmed accurate) wiring diagram for one of those. I don't even know which plug goes to the ECU and which goes to the F1 TCU (or if it matters).

The picture on the left is the F1 TCU as per the manuals. However, the gated version was proven to be different from the manuals. The gated version on the right is correct.

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If you could gently pull back the rubber boots on the plugs and see if at least the wire colours match the pin numbers that would be very helpful. The wire colours in general should tell you which is the F1 plug and which is the Motronic ECU plug. Note that the pin numbering on the F1 TPS is 3-2-1 and 3-2-1 (not as shown).

In theory, the Motronics ECU TPS plug wiring on the F1 car should be the same as on the gated car (i.e. grey/white on 3, black/white on 2 and red/blue on 1)

The pale numbers next to the wires are the pin numbers on the ECU/TCU.

I've been told that on later cars, the wire which goes to the wiper arm on the potentiometer is shielded. I don't know if this will prevent you from identifying the wire colours.

 

I just checked the resistance value range on my TPS with the TPS fitted to the car and they were completely different from the values in the WSM. Either the throttle/throttle linkages are set up improperly not allowing the TPS to move through its complete range (by a significant margin).... or it's normal

Here are my values:
Pins:
1 - 2 : 1.991 k ohms (at all pedal positions). Values within tolerance.
2 - 3 : 1.062 k ohms (no throttle) and 1.915 k ohms (at full throttle). Values way out of tolerance
3 - 1 : 2.665 k ohms (no throttle) and 1.796 k ohms (at full throttle). Values way out of tolerance

These were on my original Bosch -004.

Here are the WSM values again.


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I fitted my new (spare) Bosch -001 and the results were somewhat similar, but the range was even less (by 46 ohms on the 2-3 pins). I may refit the old one.

I took voltage measurements on the TPS connector sockets with the ignition on (plug not connected), and found that both 1 and 3 pins have voltages on them.
pin 1 = 5.o volts (I think this is the normal voltage that the ECU sends to the TPS)
pin 3 = 5.8 volts (Is this a bias voltage as discussed earlier?). I couldn't backprobe the plugs to see what the voltages are with the plug connected. I would have damaged the plastic seals.

It was very fiddly and time consuming doing this. Be warned )))

I have a new engine harness on my car, and the TPS wire colours do seem to be different from the wiring diagrams. Hard to see in this photo, but the colours were:
pin 3: white/grey (not grey/white). Possibly TPS output signal wire. The important one.
pin 2: black (not black/white). Earth wire.
pin 1: red/blue. Possibly ECU normal supply voltage.

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My plug is black which makes it difficult to compare with your blue and white plugs.

Note that the TPS has additional fixed value resistances as well as the potentiometer.

 

The values given in the table above provided by Ian are the min and max values of the potentiometer, not the values at idle and full throttle positions. Here are the values of my new 0 280 122 004 at the stops of the potentiometer:

1 - 2 : 1.98 k (at all pot positions)
2 - 3 : 0.91 k (end position 1), 2.68 k (end position 2)
3 - 1 : 2.69 k (end position 1), 0.91 k (end position 2)

The pot has wider angular travel that the spindle of the TB so, when the pot is attached, the wiper will be a bit above the "end position 1" at idle position and it will not reach its "end position 2" at full throttle. The pot is designed in this way to avoid the risk of it being forced against its stops by the TB spindle.

 

We just have to figure out what is normal when fitted to the car.

Where is the "70+%" coming from on the OBD2 scanner? My highest 2-3 value is 1.915kohms. That's about 70% of 2.7k, but the graph begins at 1.062k ohms (idle) on my car, not zero ohms.

 

That's a big ask because the F355 F1 cannot talk to an inexpensive OBD2 scanner. It actually does not broadcast its data on the OBD CAN bus so ... unless the owner also owns a $40,000 Leonardo scanner, there is no way to read this data.

I have a 99 355F1 engine out in the garage (outside of the car) right now so I can do a few things if you know what you want to ask for.

 

The Motronic ECU only uses one side. The F1 TCU uses the other side. You just have to figure out which is which. I guess that will be easy if you have a scanner. If you remove one plug and turn on your OBD2 scanner, you won't see any changes when you push the accelerator. Or you could just pull the boots on the connectors to look at wire colours (take photos if possible.) The F1 plug should have a pink/black wire.

As you say, we may be heading in the wrong direction, but this kind of stuff will be really helpful in the future (and by doing these checks, you will be paying us back for our efforts).

 

Mitch, do you have the same plug colours on your TPS? (and are they in the same locations?)

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Yes,

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Good to know, thanks, Mitch. Your rubber boots don't look like they could handle a removal and install, so I won't ask

 

Much appreciated. Thanks for trying. With a bit of imagination, it looks like your white plug (Motronic ECU) wiring is the same as my non-F1 car.

3: grey/white (output wire, low resistance to high resistance with throttle application)
2:black/white (earth)
1: red/blue (power?)

The F1 plug colours are still a little fuzzy.

One WSM F1 diagram, which has no pin number markings, shows:

black (definitely earth)
pink/black (power, I assume)
grey/white (definitely output wire)

Another WSM diagram shows:

3: black (definitely earth)
2: pink/black (possibly power as it supplies two different F1 sensors)
1: grey/white (output wire?)

Unfortunately, all of your blue (F1) plug wires looked striped.

From the wiring diagrams, the F1 half of the sensor is not wired up the same way as the Motronic ECU half. The earth and power wires are swapped. Can you confirm which pin goes to earth on your car with an ohmmeter (power off the car)? Maybe check the voltages on the other pins with the power on (TPS disconnected)?

Here are your values:

You seem to be getting a much higher resistance range than I am. I'm wondering if there is something wrong with my throttle bodies. Or perhaps the geometry on my RHD car is different. I have some extra linkages.

 

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Actually, that doesn't make sense. I have the same Motronics ECU as the USA cars. It would need to see the same TPS resistance values.

The range between your lowest and highest values on pins 2-3 is 1.36 k (mine is only around 0.85 k)
The range between your highest and lowest values on pins 1-3 is 1.59 k (mine is only around 0.87 k)

Weirdly, I get full pedal travel (fully up to carpet), but both of my TPS's new and old, give approximately the same ranges. How is the ECU compensating for this?