Missfire & throttle pot mystery

[big_treacle]

Hi all,
I've had a bit of a missfire/rough-running at low revs for a while which was a bit annoying but not too bad. It suddenly got worse & I decided to try and sort it out. I changed the plugs, leads and coilpacks which annoyingly made no difference (especially considering the amount of skin and blood invested!), but looking at the old plugs convinced me the problem was only affecting the O/S.
So today I unplugged the O/S Throttle pot & it is magically cured! Plug it in again and it all goes wrong.
I'm assuming this means that the O/S TP is probably knackered. Is this true? How can I test to make sure?
Also, how come the engine can run fine on just one good TP???
Cheers all

[itiejim]

If one throttle pot dies the ecu takes the reading from the other side.

Sounds like a new tps will cure it!

[Nickccc]

If one TP goes out, the ECU can substitute the good reading ( when the other TP is unplugged).
Switch the TP's around if the bad running moves banks it's the TP
if it doesn't it's your wiring.
If you have the lead and software use this.

[big_treacle]

OK cheers. So once I've figured out whether it's TP or wiring, do I have to do any magic or can I simply plug in some new bits and just carry on as before?

[Nickccc]

I'd want to see it's set up in sync with the other side realy.
If it was running fine before you may get lucky and it'll be ok to just switch
over. Pull the boot off the TP and make sure you havn't snagged the
wire whilst fitting the new bits.

[big_treacle]

Righto

[Byker28i]

Don't think I'd bother upseting the throttle pot, just plug in the laptop and check the readings, it should got from 18-19 smoothly upto 80-90 from memory.

When mine went it went 18, then 90m then any random reading in between. It made the drive home interesting which is when I discovered the car runs better on one than a pair with one being a faulty pot.

[Nickccc]

I'm presuming the OP doesn't have the software or lead.
I did mention using it earlier.
No he's not got it or he'd be posting screen captures of TP readings.

[stuthemong]

... the OP isn't going to manage setting up a new TP without the software though....

search ebay for a old laptop, £30 will sort it, then you can see what you are doing

[big_treacle]

I have a laptop but no software or lead as yet...