Throttle pot wiring Megasquirt

[Belle427]

I'm just finishing up a megasquirt conversion and when initially setting up the throttle pot calibration it's working in reverse, ie no throttle is reading 70 % and full throttle 0%.
Could anyone tell me which wires I need to switch at the throttle pot to correct this ? (I'm assuming that's the problem).
I thought it might be the 2 outer wires.
Thanks

[Belle427]

Thanks all, just wanted to double check.

[Belle427]

Looks a good solution.
Can i ask did you use the existing cts and need to calibrate it in Tunerstudio?
Edited to add I found the information online and calibrated the existing rover item.

Edited by Belle427 on Friday 2nd August 16:26

[Belle427]

I see racetech sell a nice conversion kit but money I don't want to spend at the moment.

[Belle427]

Yes I've done that, test fired the engine and although it runs I can only keep it going by feathering the throttle.
Afr goes off the scale @ 19:1 so I'm getting Shaun of Ms2 tuning to remotely connect later to see if he can adjust it for me.
Looks a very good piece of software Tunerstudio.

[Belle427]

I can mail it to you if you pm me an address.

[Belle427]

Dougal9887 said:

I found the hotwire TPS, when used with Megasquirt, to have poor resolution and erratic readings when viewed on the MS TPS gauge.
I changed to the Emerald supplied Colvern TPS which has wide resolution and super smooth action when viewed in MS.
it does however require that you make up a small adapter spindle and I also decided to mount it on an aluminium plate incorporating a small bearing to support the shaft as the Colvern TPS looks a bit fragile if used to support the shaft.

Dougal.

Be interested to know how this has worked for you, I had a slight issue with the original Lucas Tps not returning to zero even after multiple calibrations. I assumed it was worn at the closed end.
I purchased a replacement upgraded Tps kit from act performance at great expense and it’s exactly the same.
The throttle is returning and not binding at all so I’m a little frustrated.

[Belle427]

My idle seems to hang when it sticks, sometimes as high as 1% even though I’ve verified the throttle plate is closed.

[Belle427]

spitfire4v8 said:

Update your min tps setting in MS with the value shown when the engine is ticking over.
I'm guessing what's happening is that the throttle spindle is moving due to play in the shaft/plenum. You've presumably set the min value with engine off, but that changes when there is vacuum against the back side of the butterfly.

Makes sense, thanks that’s great advice.

[Belle427]

I have an enlarged 72 mm plenum which may exaggerate the problem, the throttle stop screw has never really been adjusted from when I received it but the throttle disc is as closed as it will go.

[Belle427]

How do you guys tackle the base idle on stuff like megasquirt when the original stepper is used, do you adjust it the same as the 14 cux?

[Belle427]

Be interested to know if anyone has used the ve analyze live part of tunerstudio.
Seems a good idea to fine tune a known good map but it gets mixed feedback.

[Belle427]

So I tried the suggestion of calibrating with engine running and it’s just as erratic on the colvern style pot.
I’m wondering if because it’s not spring loaded like the original Lucas Tps then the spindle play may be affecting it more.
Going to change it back tomorrow and see what happens.

[Belle427]

The lucas pot was hanging slightly but the act supplied colvern is much worse, it is a very good interference fit in the spindle end though.
Will switch back and go from there.

Edited by Belle427 on Monday 14th October 14:30

[Belle427]

Why does it go lean (19:1) is it because its moving to the wrong point in the map?

[Belle427]

Mainly at low throttle openings on the move, more throttle input seems to improve it.

[Belle427]

Great, thanks.
My car was mapped using just Alpha N but i also have a Map sensor fitted.
As an experienced mapper why would Alpha N be beneficial on a car thats just used on the road?
I see various opinions on what suits the Rover V8 best but there seems to be no definite answer.

[Belle427]

ed_crouch said:

Alpha-N is normally used on cars using individual throttle bodies, or cars with really wild cams where the vacuum signal is really erratic on idle. Basically for nutterbd racing engines. The quantity under measurement is the amount of air flowing through the intake system at any time (mass flow rate), and generally plenum (if fitted!) vacuum is a good indicator of that quantity. Throttle opening is a reeeeeeasonable estimate of the mass flow of air, but by the time we're resorting to throttle angle, things are getting a bit tenuous, and the idle starts to get somewhat erratic. Seems to work well flat-out, which is perhaps all that matters on a race engine?

Basically use speed-density if at all possible - it'll give better road manners. Interestingly a pal of mine is working on a ToF ultrasonic type flow sensor for both true air speed and density...

Right, I'm off to find out why I'm getting lots of sync errors on Tuner Studio. Might be because the coilpacks are right above the VR crank sensor wiring, even though its screened... Harumph.

Ed.
P.S. The paid for version of MegaLogViewer HD is awesome. Well worth 40 bucks.

Thanks.
These systems seem to be very critical in where they are grounded.
Are all your sensor grounds going back to the Ecu?