TVR S3 - wiring error??
Discussion
Hi,
I’ve been rearranging my engine electrics – moving the coil to a cooler position, relocating the 8way connector and removing the sticky electrical tape and replacing with heat protecting sleaving. Looking better already!
However while in the process of doing this, I have discovered the Throttle Pot had clearly been previously tested (re-soldered cables etc) - A mains flex had been used (ok I guess, offers good protection etc.) and noted one of the wires in the lead had been cut, right at the butt end of the flex, probably done while stripping the flex sheath.
So all this time I’ve been driving around with no input from the T/P......interesting!
So on reconnection and testing the T/P with an oscilloscope for spikes, all looks good.
Now all wired back together; hardwired without the 8way connector (will replace with a good quality one in due course).
However she fails to start with the throttle pot connected – but will start ok and run with it disconnected (back in safe mode).
Although I took care to connect everything back as existing, I have noticed a discrepancy with my injector wiring - in that it does not match the diagram in the Steve Heath Bible (2nd Ed). Please see image attached. (my current wiring shown in pencil).
The diagram shows the idle valve connected to the brown [N] wire (front three injectors) mine is wired to the black [B] (common 12V rail).
Is anyone able to comment on which is correct, or suggest any other reasons why it fails to start with the throttle pot connected?
Many thanks – any advice welcome…….
I’ve been rearranging my engine electrics – moving the coil to a cooler position, relocating the 8way connector and removing the sticky electrical tape and replacing with heat protecting sleaving. Looking better already!
However while in the process of doing this, I have discovered the Throttle Pot had clearly been previously tested (re-soldered cables etc) - A mains flex had been used (ok I guess, offers good protection etc.) and noted one of the wires in the lead had been cut, right at the butt end of the flex, probably done while stripping the flex sheath.
So all this time I’ve been driving around with no input from the T/P......interesting!
So on reconnection and testing the T/P with an oscilloscope for spikes, all looks good.
Now all wired back together; hardwired without the 8way connector (will replace with a good quality one in due course).
However she fails to start with the throttle pot connected – but will start ok and run with it disconnected (back in safe mode).
Although I took care to connect everything back as existing, I have noticed a discrepancy with my injector wiring - in that it does not match the diagram in the Steve Heath Bible (2nd Ed). Please see image attached. (my current wiring shown in pencil).
The diagram shows the idle valve connected to the brown [N] wire (front three injectors) mine is wired to the black [B] (common 12V rail).
Is anyone able to comment on which is correct, or suggest any other reasons why it fails to start with the throttle pot connected?
Many thanks – any advice welcome…….
Thanks for the prompt response and the offer of the spare T/Pot.
I may have to try that route if everything else is correct. I'll keep you updated!!
I'm just curious about the apparent error on the wiring ... the 12V common (Black)on the drawing has seven wires (1 incoming and 6 wires to injectors). Mine had 8 wires the extra one was wired across to the idle valve. They were crimped together in a transparent sleeve which I think would have been a factory fit item - see photo.
So either, 1) incorrectly wired from factory, 2) the see-through crimp is a later error, 3) the wiring diagram is wrong.
Question is… what does the idle valve expect?? -12V feed or pulsed earths from injector bank1-3-5 ??
I think I'll take a punt and trust the boys from Blackpool - I'll wire as per drawing and see if she still rejects the throttle pot, I'll do all the other voltage tests too to ensure the ECU is getting all the information.
If anyone can confirm these crimp connectors are factory items – that might shed some light here..
Thanks.
I may have to try that route if everything else is correct. I'll keep you updated!!
I'm just curious about the apparent error on the wiring ... the 12V common (Black)on the drawing has seven wires (1 incoming and 6 wires to injectors). Mine had 8 wires the extra one was wired across to the idle valve. They were crimped together in a transparent sleeve which I think would have been a factory fit item - see photo.
So either, 1) incorrectly wired from factory, 2) the see-through crimp is a later error, 3) the wiring diagram is wrong.
Question is… what does the idle valve expect?? -12V feed or pulsed earths from injector bank1-3-5 ??
I think I'll take a punt and trust the boys from Blackpool - I'll wire as per drawing and see if she still rejects the throttle pot, I'll do all the other voltage tests too to ensure the ECU is getting all the information.
If anyone can confirm these crimp connectors are factory items – that might shed some light here..
Thanks.
I seem to recall that there are two types of throttle pot which have different pin-outs. Is it possible you've had the 'wrong' type fitted without the corresponding correction to the loom? It might not have been apparent if the loom was accidentally broken at the same time, but showing up now since you've fixed it.
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