Club 80-90 Forums

Hi

Got a poorly van at the moment - stalling and sudden loss of power. I've got a weak yellow spark at the plugs.

When I measured primary/secondary coil resistance, it was out of spec (secondary coil 4000 ohms, spec 2400-3500 ohms). The coil is only a couple of years old, genuine bosch green label.

I bought a replacement bosch part which arrived today - it's even worse - 4400 ohms. Made in Brazil stamped on the label

Can anyone recommend a decent alternative brand / source? Euro Car Parts stock JP Group - are they any good?

Cheers
Jim

My guess is its not the coil at fault.

Trouble is, the Bentley manual says that coil must be ok before proceeding to check the next component

yes but sometimes ypu have to stand back and consider other tests before spending more money
Have you tried bypassing ignition 12V and connecting 12V direct to coil?

https://www.brickwerks.co.uk/brickwerks ... ion-coils/" onclick="window.open(this.href);return false;

grey label can be much higher on secondary both will work.

itchyfeet wrote:Have you tried bypassing ignition 12V and connecting 12V direct to coil?

So a weak spark could be caused by voltage less than 12v from ignition?

itchyfeet wrote:grey label can be much higher on secondary both will work.

So I could also try a grey label coil?

jimrat wrote:

itchyfeet wrote:Have you tried bypassing ignition 12V and connecting 12V direct to coil?

So a weak spark could be caused by voltage less than 12v from ignition?

itchyfeet wrote:grey label can be much higher on secondary both will work.

So I could also try a grey label coil?

yes and yes, everything else is the same. the differerence was all about longer service intervals.
A bad ignition switch or 12 V connection could cause this.


Check your battery voltage too, batteries die in cold weather.

Check earth to engine head by coil, earth under coil.

these are all free checks and tests.

one more thing multimeters often lie to you, a bad connection may show 12V but when you actually try and draw power the voltage falls away becuase of high resistance.

A battery at 12V is almost flat, it should be 12.3 12.4 12.5+ to be healthy

Done a few more checks today:

Battery voltage at alternator was 12.7 volts
All earth connections cleaned and remade
With 12v direct to coil (bypassing ignition switch), I still get a weak yellow spark
Tried the new bosch coil - no improvement- yellow spark
Ran through a few more Bentley tests - the Hall Control Unit test fails - I don't get a transient 2v at the coil.
Hall Control Unit is only 4 months old (Beru, from Brickwerks). Spark plugs, leads, dizzy and rotor arm all replaced at the same time.

Why would this fail so quickly? Bit reluctant to buy another from Brickwerks as they clearly state 'no returns on this item'. If it turns out to have died, is it reasonable to ask for a £50 refund?

Cheers
Jim

I'd buy second hand dizzy you can get them cheaper than hall units, even if the vac can has gone they are not expensive.

Leads, distributor cap or rotor arm?

Hall control unit/ignition amplifier. Was it fitted with heatsink paste?

Oh sh*t I remember seeing the paste in the box after I'd fitted the amp

I'd forgotten about that - might explain premature failure...