coil ohm readings, LT and HT

I'm not sure if this is the correct Newsgroup for this question but here
goes.

Could someone tell me how critical the manual-specified ohm ranges are for
the LT and HT resistances at the coil and would I be right in thinking that
the tolerances of the LT range is less because it is a smaller measurement?

On the existing coil that's fitted to my Fiat Tipo 1.4 the LT measurement
should be between 0.666 and 0.805 ohms (from memory!) but reads 1.3 whereas
the HT reading falls within the quoted higher range. The 'new' (breakers)
coil I'm thinking of fitting has a good LT reading but is higher on the HT
side.

The symptoms are: the ignition system stops delivering a spark within a few
miles (dies at the lights) but then returns to normal after 'a rest' -
presumably when the faulty component has had a chance to cool down - and the
car runs well till next time.

I'd appreciate any suggestions. Thanks.

Lez

Your LT reading is double, the coil is fried.

If the 'new' one is also out of spec, don't bother with it. It will
give you the same grief shortly.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's

Lez Hammans wrote:
>
> I'm not sure if this is the correct Newsgroup for this question but here
> goes.
>
> Could someone tell me how critical the manual-specified ohm ranges are for
> the LT and HT resistances at the coil and would I be right in thinking that
> the tolerances of the LT range is less because it is a smaller measurement?
>
> On the existing coil that's fitted to my Fiat Tipo 1.4 the LT measurement
> should be between 0.666 and 0.805 ohms (from memory!) but reads 1.3 whereas
> the HT reading falls within the quoted higher range. The 'new' (breakers)
> coil I'm thinking of fitting has a good LT reading but is higher on the HT
> side.
>
> The symptoms are: the ignition system stops delivering a spark within a few
> miles (dies at the lights) but then returns to normal after 'a rest' -
> presumably when the faulty component has had a chance to cool down - and the
> car runs well till next time.
>
> I'd appreciate any suggestions. Thanks.
>
> Lez

Thanks a lot Mike. I've taken your advice and am going for a (real) new one.
Should've done that in the first place!

Thanks mate!

Lez

"Mike Romain" <romainm@sympatico.ca> wrote in message
news:40AA619F.3381E216@sympatico.ca...
> Your LT reading is double, the coil is fried.
>
> If the 'new' one is also out of spec, don't bother with it. It will
> give you the same grief shortly.
>
> Mike
> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> 88 Cherokee 235 BFG AT's
>
> Lez Hammans wrote:
> >
> > I'm not sure if this is the correct Newsgroup for this question but here
> > goes.
> >
> > Could someone tell me how critical the manual-specified ohm ranges are
for
> > the LT and HT resistances at the coil and would I be right in thinking
that
> > the tolerances of the LT range is less because it is a smaller
measurement?
> >
> > On the existing coil that's fitted to my Fiat Tipo 1.4 the LT
measurement
> > should be between 0.666 and 0.805 ohms (from memory!) but reads 1.3
whereas
> > the HT reading falls within the quoted higher range. The 'new'
(breakers)
> > coil I'm thinking of fitting has a good LT reading but is higher on the
HT
> > side.
> >
> > The symptoms are: the ignition system stops delivering a spark within a
few
> > miles (dies at the lights) but then returns to normal after 'a rest' -
> > presumably when the faulty component has had a chance to cool down - and
the
> > car runs well till next time.
> >
> > I'd appreciate any suggestions. Thanks.
> >
> > Lez

Further to my original posting about coil resistances, this query results
from the fact that, though my old car (G-reg Fiat Tipo 1.4 DGT) would work
perfectly for most of the time, every now and again (sometimes 3 times
within 50 miles then perhaps not for 200 miles) it would run rough and
'peck' for a few yards as if trying to stall, and/or die at a roundabout or
set of lights. Sometimes it would key straight away after that, sometimes it
would need to 'rest' for a few minutes before it would start again. Bloody
inconvenient.

I'd replaced HT leads, distributor cap, rotor arm, spark plugs etc. hoping
to cure the fault but, when it continued, I'd assumed it was fuel
starvation - carb needed cleaning or a vapour lock or something - until I
broke down again last weekend. The recovery guy showed it to definitely be
an ignition fault (no spark for a while then it started sparking again and
fired up). He thought the fault might be in the ignition module on the side
of the distributor.

As a garage could end up charging me more than what the car's worth to find
the fault, I thought it would be cheaper to replace the unit - and, while
I'm at it, the coil - which would leave virtually everything on the ignition
side as new. Stupidly, not realising I didn't need to, I took the
distributor out (but I can sort out the timing later). Having made the
mistake I thought I might as well take it home and clean it up. I took off
the rotor arm and plastic protector and, when I looked inside, I found a
greasy bit of black metal spring-clip floating about! I can see it's snapped
off from an 'L-shaped' clip that is riveted to the top inner steel plate.
The loose bit should go down onto a short plastic (I think) stem that meets
the slotted plastic rod that comes in from the vacuum unit.

I can't really see the purpose of the clip - it doesn't look vital but it's
there - and it's obviously been broken for a while. Which means the car has
been starting and running okay with it broken off!

Not knowing much about distributors (apart from their purpose) could anybody
say, from reading this, whether the loose bit of clip could have been
creating an intermittent electrical short and causing the spark to fail?

I'd value your thoughts. Thanks -

Lez


"Lez Hammans" <LezH(takethisout)@bigfoot.com> wrote in message
news:JYHqc.20015$J_7.3949@front-1.news.blueyonder.co.uk...
> Thanks a lot Mike. I've taken your advice and am going for a (real) new
one.
> Should've done that in the first place!
>
> Thanks mate!
>
> Lez
>
> "Mike Romain" <romainm@sympatico.ca> wrote in message
> news:40AA619F.3381E216@sympatico.ca...
> > Your LT reading is double, the coil is fried.
> >
> > If the 'new' one is also out of spec, don't bother with it. It will
> > give you the same grief shortly.
> >
> > Mike
> > 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> > 88 Cherokee 235 BFG AT's
> >
> > Lez Hammans wrote:
> > >
> > > I'm not sure if this is the correct Newsgroup for this question but
here
> > > goes.
> > >
> > > Could someone tell me how critical the manual-specified ohm ranges are
> for
> > > the LT and HT resistances at the coil and would I be right in thinking
> that
> > > the tolerances of the LT range is less because it is a smaller
> measurement?
> > >
> > > On the existing coil that's fitted to my Fiat Tipo 1.4 the LT
> measurement
> > > should be between 0.666 and 0.805 ohms (from memory!) but reads 1.3
> whereas
> > > the HT reading falls within the quoted higher range. The 'new'
> (breakers)
> > > coil I'm thinking of fitting has a good LT reading but is higher on
the
> HT
> > > side.
> > >
> > > The symptoms are: the ignition system stops delivering a spark within
a
> few
> > > miles (dies at the lights) but then returns to normal after 'a rest' -
> > > presumably when the faulty component has had a chance to cool down -
and
> the
> > > car runs well till next time.
> > >
> > > I'd appreciate any suggestions. Thanks.
> > >
> > > Lez
>
>

That sounds like something holding the vacuum advance in place.

This would be for high speed running and maybe idle depending on the
setup.

It shouldn't make it cut out.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's

Lez Hammans wrote:
>
> Further to my original posting about coil resistances, this query results
> from the fact that, though my old car (G-reg Fiat Tipo 1.4 DGT) would work
> perfectly for most of the time, every now and again (sometimes 3 times
> within 50 miles then perhaps not for 200 miles) it would run rough and
> 'peck' for a few yards as if trying to stall, and/or die at a roundabout or
> set of lights. Sometimes it would key straight away after that, sometimes it
> would need to 'rest' for a few minutes before it would start again. Bloody
> inconvenient.
>
> I'd replaced HT leads, distributor cap, rotor arm, spark plugs etc. hoping
> to cure the fault but, when it continued, I'd assumed it was fuel
> starvation - carb needed cleaning or a vapour lock or something - until I
> broke down again last weekend. The recovery guy showed it to definitely be
> an ignition fault (no spark for a while then it started sparking again and
> fired up). He thought the fault might be in the ignition module on the side
> of the distributor.
>
> As a garage could end up charging me more than what the car's worth to find
> the fault, I thought it would be cheaper to replace the unit - and, while
> I'm at it, the coil - which would leave virtually everything on the ignition
> side as new. Stupidly, not realising I didn't need to, I took the
> distributor out (but I can sort out the timing later). Having made the
> mistake I thought I might as well take it home and clean it up. I took off
> the rotor arm and plastic protector and, when I looked inside, I found a
> greasy bit of black metal spring-clip floating about! I can see it's snapped
> off from an 'L-shaped' clip that is riveted to the top inner steel plate.
> The loose bit should go down onto a short plastic (I think) stem that meets
> the slotted plastic rod that comes in from the vacuum unit.
>
> I can't really see the purpose of the clip - it doesn't look vital but it's
> there - and it's obviously been broken for a while. Which means the car has
> been starting and running okay with it broken off!
>
> Not knowing much about distributors (apart from their purpose) could anybody
> say, from reading this, whether the loose bit of clip could have been
> creating an intermittent electrical short and causing the spark to fail?
>
> I'd value your thoughts. Thanks -
>
> Lez
>
> "Lez Hammans" <LezH(takethisout)@bigfoot.com> wrote in message
> news:JYHqc.20015$J_7.3949@front-1.news.blueyonder.co.uk...
> > Thanks a lot Mike. I've taken your advice and am going for a (real) new
> one.
> > Should've done that in the first place!
> >
> > Thanks mate!
> >
> > Lez
> >
> > "Mike Romain" <romainm@sympatico.ca> wrote in message
> > news:40AA619F.3381E216@sympatico.ca...
> > > Your LT reading is double, the coil is fried.
> > >
> > > If the 'new' one is also out of spec, don't bother with it. It will
> > > give you the same grief shortly.
> > >
> > > Mike
> > > 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> > > 88 Cherokee 235 BFG AT's
> > >
> > > Lez Hammans wrote:
> > > >
> > > > I'm not sure if this is the correct Newsgroup for this question but
> here
> > > > goes.
> > > >
> > > > Could someone tell me how critical the manual-specified ohm ranges are
> > for
> > > > the LT and HT resistances at the coil and would I be right in thinking
> > that
> > > > the tolerances of the LT range is less because it is a smaller
> > measurement?
> > > >
> > > > On the existing coil that's fitted to my Fiat Tipo 1.4 the LT
> > measurement
> > > > should be between 0.666 and 0.805 ohms (from memory!) but reads 1.3
> > whereas
> > > > the HT reading falls within the quoted higher range. The 'new'
> > (breakers)
> > > > coil I'm thinking of fitting has a good LT reading but is higher on
> the
> > HT
> > > > side.
> > > >
> > > > The symptoms are: the ignition system stops delivering a spark within
> a
> > few
> > > > miles (dies at the lights) but then returns to normal after 'a rest' -
> > > > presumably when the faulty component has had a chance to cool down -
> and
> > the
> > > > car runs well till next time.
> > > >
> > > > I'd appreciate any suggestions. Thanks.
> > > >
> > > > Lez
> >
> >