Throttle Pots and Ignition Coils.

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Bloody Throttle pot!

Any thoughts on why I can only manage about 6 months or 3000 miles avarage life from throttle pots? The symptoms are poor idle and occaisionally missing at constand speed. I haven't got the voltmeter out yet but disconnecting the throttle pot clears the fault. (It isn't the idle valve that's causing the fault.)
Anyone else go through this number of TP's?

Secondly, and it may linked, I have some HT leakage on the LT (Neg) connection on the coil.
LT (Pos) and (Neg) goes into the coil and transforms across to the secondary winding. The (Pos) of the secondary is the HT to the Distributor Cap I know, but is the HT (Neg) common to the LT (Neg)? Personally I doubt it, and think that HT (Neg) should be Earthed to the coil case. Am I correct?
Incidentally, the coil is the standard round motorcraft coil, nothing elaborate, as per standard S2.

Thanks folks,

Jas.

[GreenV8S]

quote:is the HT (Neg) common to the LT (Neg)? Personally I doubt it, and think that HT (Neg) should be Earthed to the coil case. Am I correct?

That's what I would expect to see, too. I imagine if the HT was earthing through the LT circuit and there was any resistance in the circuit, you could potentially (sorry) get a heck of a voltage spike as the coil pushed the negative HT down instead of pushing the positive HT up. Anything else connected to that -ve LT would see the voltage spike. LT components wouldn't be rated for anything like that sort of voltage, no idea what would happen but can't be good.

Is it possible the coil is faulty?

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quote:
Is it possible the coil is faulty?

Rekon you're right Pete. Anyone else with suggestions?

(P.S. Pete, if you sh@g the diff again, talk to Phil Stuart at Road & Race Transmissions, in Sevenoaks I think I'll try and dig out a phone number for you if you want).

Jas.

[samdring]

quote:Bloody Throttle pot!

Any thoughts on why I can only manage about 6 months or 3000 miles avarage life from throttle pots?
Anyone else go through this number of TP's?


Thanks folks,

Jas.

Had S2 since 1 Dec 01 and on 4th Pot - the third of which lasted only 1 or 2 miles.
Garage made real stink with Ford and was compensated for lost time/labour. I think we all should claim compo - it just might make Ford sit up!!

Sam

[Dave_H]

The problem is with Ford, as my neighbour (mechanic) has had many 2.9 Granada owners say the same thing.

CUE JOHNO: As Mark, you've fitted a speed six throttle pot with no problems - could this be the answer??

Cheers,

Dave.

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Spoke to TVR Centre today, apparently you can also use 4.2 / 4.5 Cerbie TP's!
I'm going to see them to compare the Ford item from my car this week so i'll post the results.

(Peter, I cut open an old ignition coil with a hacksaw today to look at the -ve HT, and believe it or not -ve HT and -ve LT are connected to each other, so mine appears to be correct!)

Jas.