Adjusting the throttle potentiometer

[YDR422]

The manual says that I need the proper Lancia kit. Is this true? I've also read that you adjust it to read 0.5volt at idle.

Anyone done this?

Cheers,
Gary

[J8N HF]

Gary
I did mine via the workshop manual method (only really a get you out of trouble method though)
Loosen the screws, open the butterfly, then let it return to the static position then do up the screws again, and it should have set itself.. If you do find out the voltages then posting them up would be most useful.
Ta
Jon

[SteveNZ]

Set the Potometer just (about 200mv) below the idle switch. Im not too sure what the switch voltage is in the IAW (im about to find out) but generally its around 800-1000mv somewhere.

J8N HF, thats a very crazy method.

0.5V at idle would be safe. Its very unlikley to to be any lower

[A1.6HPE]

Hello,
Sorry SteveNZ but I'm with J8N HF. That's how I do mine. There is no such thing as an "idle switch" with the IAW system.

Leo

[rossocorsa]

as far as i know you can set it by reading the resistance of the potentiometer assuming it is in good order you should see a smooth progression as the throttle is moved can't remember off hand whether it is highest or lowest resistance to aim for when throttle is closed, seems to me to be a lot safer than risking playing with live electrics on sensitive equipment like ecus. I now have a FLT and can confirm that my setting was near enough spot on when checked by it

[SteveNZ]

Hello,
Sorry SteveNZ but I'm with J8N HF. That's how I do mine. There is no such thing as an "idle switch" with the IAW system.

Leo

With all respect, that method may work but its far from the best way to do it.

The TPS provides 1 thing, a signal voltage. Thats is the one and only thing the ecu is interested in too, nothng elce matters. Settting by signal voltage is the best method. It will also show up possible problems that may be lurking.

There isn't an idle switch built into the TPS as such, its only a 3 wire. However there will be a "soft" idle switch built into the ECU. The switch will be "tripped" when the TPS signal voltage exceeds a preset value. This is usually around 800-1000mv. For the ecu to controll the idle correctly the idle voltage needs to be set below this switch voltage (i.e. ecu sees TPS at idle) If its set higher the ecu will not control idle speed (i.e. TPS sees TPS on part throttle). This can cause erattic or very high idle. Typically 200mv below the switch is corrrect.

Im sorry I dont have the actual voltage levels for an IAW. My car is running fine so no need to check. Its not hard to figure it out though. just increase the TPS voltage (without changing the throttle position) until you hear the the idle speed change. This is usually very easy to notice. That is the idle switch.

[A1.6HPE]

Hello SteveNZ,
I am sure that your comments are well intentioned but I suspect you are offering advice based upon theoretical knowledge. My assistance is based upon my own practical experience that worked successfully on two Deltas of mine.
The throttle position sensor has a continuous resistive track for the entire rotation. The IAW software monitors the throttle position (and other parameters) and matches the igntion timing and petrol supply accordingly throughout the entire range of throttle opening, so does not "switch".

Anyway, the Lancia workshop manul does not specify how to install or adjust a new potentiometer but it does advise how to test it. The impedance/resistance between contacts B and C should vary smoothly between 450 ohms down to 80 ohms from closed to fully open. I'll check mine tomorrow and advise what it reads.

Leo

[A1.6HPE]

I just checked the impedance of the throttle potentiometer on my 8V Delta integrale. I replaced the potentiometer about two years ago and it is an updated black one rather than the older red ones, so not sure if that makes a difference. The reading at throttle closed is 630 ohms and wide open it was 130 ohms. A bit higher than what the manual says but the engine has run fine for 2 years and fuel consumption is what I would expect (about 20 to 25 miles per gallon).
The software re-samples the settings frequently (about 2 minutes I believe) so perhaps the actual impedance doesn't actually matter, it may only compare the overall max and min values and work from those.

Leo

[rossocorsa]

I believe there are two designs of switch the early ones having a distinct idle position later ones (the majority) having simply a smooth resistance/voltage change. early types may well predate grales

[A1.6HPE]

Hello Alan,
The Weber-Marelli units are all smooth resitive type. The early Bosch (eg LE as on Betas) have contacts for the idle and the full throttle positions. The difference is that the Bosch systems all measure the air-flow into the plenum chamber (either via a flap or "hot-wire" tube) and the Weber-Marelli simply works on the throttle angle and the vacuum/pressure in the plenum chamber.

Leo