No spark when cranking

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Giz
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No spark when cranking

Post by Giz »

Hi,
I've searched the forum but can't find an answer to my ignition issue.
The van is a 1990 diesel which has been converted to run a 2.1 5 cylinder Audi engine from which car I'm not sure.

The problem I have is that when the key is in the normal running position I have 12v at the coil. When I crank the starter I have no spark.
I've had a spark tester between the coil and the HT lead and there is a spark but only once the key has been released from the cranking position. If I time it right with the throttle I can get it to fire but when the engine is cold it takes a while.

I've been on it for hours going round in circles.

Any ideas?

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Aidan
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Re: No spark when cranking

Post by Aidan »

the disappearing 12V scenario - check for resistance in the connections on the stud in the black box and the connections to the relays in the black box above the coil if still fitted, I had this once on a 2.1, temporary fix by RAC man was a fused link bypassing one of the relays, later I undid the nut on the stud and remade the end of the eye'd cable from the alternator and the cable to the relays and that solved the issue long term, you would test for 12v at the stud and when cranking it disappeared

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bigherb
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Re: No spark when cranking

Post by bigherb »

Check you still have 12V at the coil when cranking the engine, sounds like you are losing it due to a faulty ignition switch.
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ajsimmo
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Re: No spark when cranking

Post by ajsimmo »

bigherb wrote:Check you still have 12V at the coil when cranking the engine, sounds like you are losing it due to a faulty ignition switch.
^^^this^^^ seconded.

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Giz
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Re: No spark when cranking

Post by Giz »

I've found the problem but not yet figured out why.
The wire to the starter solenoid is causing the issue, I've bypassed it with a push button to a relay and supplied the solenoid through the relay.
Something must be earthing to chassis and confusing the ECU.
I've belled it out with the battery disconnected and it's clear but as soon as the key is turned to the crank position it shows 0.3Ω.
A few days before this my switched supply to the radio packed up on the fuse panel, I think it was G5. That's dead now.
Whilst I was testing i replaced the battery cable to the starter and I've gone direct from battery to the connector in the black box and added an extra earth strap from battery to earth point by the coil to rule out any supply problems.
The feedback to earth is coming from the lights fed from connector C which all work fine.
🤷

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