Will only start after ignition key is released?

[rdl001]

1996 Chim,
Having recently fitted a new Bosch Coil (TVR E0057) and Ignition Module (TVR E0411) from TVR parts Ltd, my engine is running so much better, particularly at higher rpm. Note: The old Lucas coil (now replaced with the Bosch) has a very high resistance and the old Lucas Ignition module (now replaced with a copy part) looks like the original.

But I have one niggling problem, that now the engine will not start until I release the key from position 3 (cranking and coil) to position 2 (run). When it cranks I am seeing about 9-10 volts. When the engine is off I see 12.8 volts, when the engine is running I see 13.5 volts. The starter motor turns very quickly, just won't start until I let go of the key.


Note: The old Lucas coil (now replaced with the Bosch) has a very high resistance and the old Lucas Ignition module (now replaced with a copy part) looks like the original.

I am pondering whether to change back to the old Lucas ignition module, any thoughts would be much appreciated.

Regards,

[rdl001]

Thanks 5ltr, but I am pretty sure that there is no ballast resistor used in this engine circuit.

[rdl001]

Yes, not quite immediately but after 3-4 start ups.

The car is running so much better with this new coil and module, I am reluctant to change them back but I may need to for diagnosis purposes.

I always worry when making repairs/modes/ upgrades etc that it's easy to disturb something else which can be totally unrelated.

[rdl001]

Thanks Penolope,

Ahh, now when I measure the voltage at the coil I get:
1) Ignition on - 0 volts

2) During cranking - 3.3 volts

Any more thoughts?

[rdl001]

So,

When I test between (+ coil terminal) to (engine ground) I see:
Ignition on, 13.2 volts
Cranking, 9 volts

When I test between (+ coil terminal) and (- coil terminal) I see:
Ignition on, 0 volts
Cranking, 3 volts

Does this mean that the new ignition module I fitted is not getting to earth?

[rdl001]

Hi Pen and Belle,

I was testing the voltages last night with my trickle charger still plugged in, so this may explain my high voltages.

on retest,

When I test between (+ coil terminal) to (engine ground) I see:
Ignition on, 12.3 volts
Cranking, 8 volts

When I test between (+ coil terminal) and (- coil terminal) I see:
Ignition on, 0 volts
Cranking, 1.7 volts

When I test between (+ battery terminal) and (- battery terminal) I see:
Ignition on, 12.3 volts
Cranking, 8.1 volts

Does that make more sense?

[rdl001]

Okay, understood.

It just seems strange (or coincidental) that after I have changed the ignition coil and ignition module that I then have a suspect battery?

Note: I have just put a feed from the positive battery terminal to the positive coil terminal and she starts when cranking, as she should.
Does that tell us anything?

By the way, thanks for all your help so far

[rdl001]

Update:

At the start of this thread I said that I had fitted a new Bosch Coil (TVR E0057) and Ignition Module (TVR E0411) from TVR parts Ltd, which cured my 'poor performance at higher RPM'.

I have now refitted the original Lucas ignition module, and the car now starts perfectly as soon as it cranks, showing 9.6 volts at the coil during cranking.
Does this mean that the 'copied part' (TVR E0411) from TVR Parts was drawing too much current and not giving sufficient voltage to the coil.

I have yet to test the car on the road, but it seems that the Ignition Module (TVR E0411) from TVR parts is not compatible with the coil they sell?, or is it just a quirk of my engine?

[rdl001]

Penelope Stopit said:

rdl001 said:

When I test between (+ battery terminal) and (- battery terminal) I see:
Ignition on, 12.3 volts
Cranking, 8.1 volts

rdl001 said:

I have now refitted the original Lucas ignition module, and the car now starts perfectly as soon as it cranks, showing 9.6 volts at the coil during cranking.

I'm curious as to how the coil supply is 9.6 Volts when the battery voltage was measured to be 8.1 Volts during cranking

Could the module have been dragging the voltage down?