Throttle Position Sensor?

[fieldl]

So I have a problem with my car there's no throttle whatsoever.  A few times on the track it's done this previously all ok and then nothing just sits at around 2000 RPM and no throttle response, switching off the power and restarting fixes it but not anymore.

We've changed the throttle body, switched the ECU, checked all the wiring and still nothing.
I have a Hondata Flashpro connected to the ECU and can see reading from the Throttle Position Sensor but the potentiometer could be faulty. 

Here it is:



It looks like an Ariel part?


I'll speak to Tom on Monday but need it quick time.  Any other ideas, we have checked the cabling with a multimeter and thats ok.  What else is there?

[AtomMadStew]

Disconnect the battery for 10 mins see if that cures it. Is the battery ok?

[fieldl]

Battery is a Varley Red Top that's only a few months old.
We've changed the ECU but haven't disconnected the battery.  What would that do?

[AtomMadStew]

Power down the whole electrical system. Sometimes can cure such a problem (sometimes only temporarily) but if you need the car urgently. It's worth a try.

[fieldl]

My car is on a master cutoff switch so is always powered down.
Can't hurt to have a go anyway.  Reading up on potentiometers they can go screwy and still give a reading.

[AtomMadStew]

There is quite a few threads on something similar but am unable to find them due to my poor Internet connection. Do a thread search mr fieldl.

[AtomMadStew]

Search limp mode or stops accelerating

http://www.atomclub.com/forum/index.php/topic,12993.0.html

[fieldl]

I've read all the threads.  It's weird as I don't get any error codes trigger on the ECU and I can see some data on the data logger that would seem to indicate its ok.  However all the symptoms sounds the same.

[John Scherrer]

It may (should!) have a fail-safe design where there are 2 potentiometers, usually linear.

As the throttle is opened one potentiometer increases whilst the other decreases - If either one fails or reports an off-limits resistance, the ECU kills the power - This prevents the engine going to an uncommanded full throttle situation.

Have you traced the wiring back and ensured that the connector at the engine end is secure etc?

[fieldl]

Ok so two potentiometers in the one unit would explain why there are 6 connectors rather than 3 we'd expect.
I think the wiring has been checked but I'll ask its certainly secure.  I have a race in two weeks so it's getting a bit urgent.
Will also talk to Tom on Monday to see if I can get a replacement as it's an Ariel part.

[fieldl]

Ok so today we took out every fuse, tested and replaced.  Along with all the relays.
Mmmm it seemed to work.  The car now runs   Although we have no real certainty as to why.

Any idea on where I can get a fuse box diagram?
Car is now off to the tuners to be mapped should be back next weekend for testing.

Looks like I might be racing after all.

[John Scherrer]

Pleased it's running now ...

Do you mean a wiring diagram or what fuse covers which function?

Do you have an Atom handbook?

[fieldl]

I'd love a wiring diagram but would settle for a diagram showing which fuse does what especially if it could include the relays. Found something along those lines for the relay box near the ECU but nothing else.

I don't have a handbook unfortunately.

[Bruce Fielding]

What model of Atom do you have?  The handbooks are different (as are the fuse boxes).

[fieldl]

It's an Atom 3 albeit a Qingdao Ariel one. The loom and fuse box should be the same as the UK car.