Electrical Problem during Cranking
Discussion
Just has an auto electrician out to take the immobiliser out of my s1 (it was faulty).
He's taken that all out ok, but has reported that it now cranks over fine but only sparks when the key comes back from the start position so in summary when its cranking there's no spark, stop cranking and it should spark (if the engine could still turn over).
Anyone got any thoughts, what does the duraspark module do etc
Can you get replacements?
What stupid wiring mess up could I have made that would rob the coil circuit of power during cranking? What relay or box could be faulty that would cause this.
He's coming back on friday to take another look.
Mike
He's taken that all out ok, but has reported that it now cranks over fine but only sparks when the key comes back from the start position so in summary when its cranking there's no spark, stop cranking and it should spark (if the engine could still turn over).
Anyone got any thoughts, what does the duraspark module do etc
Can you get replacements?
What stupid wiring mess up could I have made that would rob the coil circuit of power during cranking? What relay or box could be faulty that would cause this.
He's coming back on friday to take another look.
Mike
Mike this is all a bit of guesswork - anyone else feel free to correct me - but as the battery voltage drops significantly when cranking the engine due to the starter load I think the ignition will be powered by a seperate circuit from the starter cranking circuit while it is turning over.
Some cars run the ignition coil with a resistor in series - when the starter is operated the resistor is bypassed by the full battery voltage being applied the other side of the resistor if that makes any sense - so the resistor is effectively out of the circuit - so the coil always expects say 9 volts which it gets either while the engine is turning over or via the resistor during normal running.
It sounds like a simple case of a wire off or broken to me, maybe as a result of removing the immobiliser.
Some cars run the ignition coil with a resistor in series - when the starter is operated the resistor is bypassed by the full battery voltage being applied the other side of the resistor if that makes any sense - so the resistor is effectively out of the circuit - so the coil always expects say 9 volts which it gets either while the engine is turning over or via the resistor during normal running.
It sounds like a simple case of a wire off or broken to me, maybe as a result of removing the immobiliser.
Edited by Barkychoc on Wednesday 22 April 20:43
It sounds like the cold start circuit that bypasses the ballast resistor is faulty - but I'd expect an auto electrician to understand that.
Look on http://www.tvrsseries.com/ and on the menu is "Electrical Drawings". Pick that and you want the 3rd one down - " TVR S General Electrics and Supplemental Fuel Injection and Electronic Speedometer". The LH pic shows the general electrics and the bit you want is at the lower left corner. I suspect that it is the wire from the coil side of the resistor to the starter or the starter itself. When the starter solenoid engages it should make a switch (of some sort - can't remember what these starters look like) and supply 12v direct to the coil. Print that diagram off and your electrician should be able to sort it.
Good luck
J
Look on http://www.tvrsseries.com/ and on the menu is "Electrical Drawings". Pick that and you want the 3rd one down - " TVR S General Electrics and Supplemental Fuel Injection and Electronic Speedometer". The LH pic shows the general electrics and the bit you want is at the lower left corner. I suspect that it is the wire from the coil side of the resistor to the starter or the starter itself. When the starter solenoid engages it should make a switch (of some sort - can't remember what these starters look like) and supply 12v direct to the coil. Print that diagram off and your electrician should be able to sort it.
Good luck
J
had a good look tonight, because the last owner has done such a good job wrapping up the wiring and then putting it in spiral bind its a nightmare to get at.
Think the electrician guy ran out of time, he did teh immob then had a quick look then had to go, he taken the wiring diagram to take a look.
Found all the right wires and the one that bypasses the resistor, there were some connectors burried under spiral wrap that I cleaned up etc but stillno joy, from what I can work out its all wired up correctly.
There was just over 11v at the coil lead at ignition on dropping to 8v while crannking
Might be daft but i have put the battery on charge as it may have been low its now reading 12v on the battery gauge rather than 11v, dont know if this will make any difference?
Have a spare duraspark module to try tomorrow, the car was sat outside for a few years withou the bonnet on so the module may have got weather damaged etc.
Interestingly after you released the key from cranking it would now and then fire one cyclinder, I guess if you keyed off just at the right time it would spark on one cylinder briefly
Think the electrician guy ran out of time, he did teh immob then had a quick look then had to go, he taken the wiring diagram to take a look.
Found all the right wires and the one that bypasses the resistor, there were some connectors burried under spiral wrap that I cleaned up etc but stillno joy, from what I can work out its all wired up correctly.
There was just over 11v at the coil lead at ignition on dropping to 8v while crannking
Might be daft but i have put the battery on charge as it may have been low its now reading 12v on the battery gauge rather than 11v, dont know if this will make any difference?
Have a spare duraspark module to try tomorrow, the car was sat outside for a few years withou the bonnet on so the module may have got weather damaged etc.
Interestingly after you released the key from cranking it would now and then fire one cyclinder, I guess if you keyed off just at the right time it would spark on one cylinder briefly
did mention the durastart module (just not its stowage), not sure how it has been stored with the last owner, all I know is the body was off and stored outside with out bonnet on, the durastart module remained on bulkhead and may/maynot have been covered.
Could this be a good suspect???, as the wiring looks to be in good condition and connected as per the diagram.
The only prob is I can't guarantee the condition of the spare I'm going to try.
M
Could this be a good suspect???, as the wiring looks to be in good condition and connected as per the diagram.
The only prob is I can't guarantee the condition of the spare I'm going to try.
M
still no joy with the new module and providing a 12v direct feed to the coil.
Now I'm really depressed.
Thinking back to my immobiliser problems, it did spark before whilst cranking just intermintently because the immobiliser relays were buzzing so maybe there an issue after the immob has been removed?
Anythoughts
M
Now I'm really depressed.
Thinking back to my immobiliser problems, it did spark before whilst cranking just intermintently because the immobiliser relays were buzzing so maybe there an issue after the immob has been removed?
Anythoughts
M
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