Discussion
Apologies for the acronyms in the title.
I have a car in (actually a V8S but that's not necessarily important) .. it has HID headlamps fitted.
When you switch on the headlamps the fuel pump primes (engine stopped, ignition on).
I've done some investigation and there's a short interruption on the signal wire from the distributor to the ECU, so the ecu thinks that for a split second as the lights are turned on that the engine is running.
I thought it was a wiring issue so have spent some time systematically removing / bypassing elements of the ignition and lighting system until I've come to this point :
I have the HIDs powered up from a slave battery so that the entire HID system is separate from the car. There is no direct electrical connection from the headlight circuit to the car and it STILL does it!
The only thing I can think of now is that there's an electromagnetic interference as the HIDs strike up initially. There is also interference on the radio which also I think confirms an airborne interference.
The transformers are in the nose of the car so practically as far as possible already from the engine/ignition system.
Question is .. has anyone come across this before (google seems to have info on wire-based interference, but not EMI from the brief search I did earlier, IE people report that running off a slave battery cured it, but not in my case)
If anyone has come across it, what did you do?
Returning the car to its own wiring source, and replacing the HIDs with conventional bulbs, completely eliminates the issue.
any ideas ?
I have a car in (actually a V8S but that's not necessarily important) .. it has HID headlamps fitted.
When you switch on the headlamps the fuel pump primes (engine stopped, ignition on).
I've done some investigation and there's a short interruption on the signal wire from the distributor to the ECU, so the ecu thinks that for a split second as the lights are turned on that the engine is running.
I thought it was a wiring issue so have spent some time systematically removing / bypassing elements of the ignition and lighting system until I've come to this point :
I have the HIDs powered up from a slave battery so that the entire HID system is separate from the car. There is no direct electrical connection from the headlight circuit to the car and it STILL does it!
The only thing I can think of now is that there's an electromagnetic interference as the HIDs strike up initially. There is also interference on the radio which also I think confirms an airborne interference.
The transformers are in the nose of the car so practically as far as possible already from the engine/ignition system.
Question is .. has anyone come across this before (google seems to have info on wire-based interference, but not EMI from the brief search I did earlier, IE people report that running off a slave battery cured it, but not in my case)
If anyone has come across it, what did you do?
Returning the car to its own wiring source, and replacing the HIDs with conventional bulbs, completely eliminates the issue.
any ideas ?
I'm betting that burnt a fair bit of time.
As said is it really a problem. You have identified that there are no stray electrical issues (shorts etc).
To cure it you would probably have to first screen the wires to/from the ignition amp which, due to the small signal, will likely be the pickup point.
You may also need to do the wire from coil to ECU.
You could start by simply wrapping the dizzy and amp in tin foil.
Steve
As said is it really a problem. You have identified that there are no stray electrical issues (shorts etc).
To cure it you would probably have to first screen the wires to/from the ignition amp which, due to the small signal, will likely be the pickup point.
You may also need to do the wire from coil to ECU.
You could start by simply wrapping the dizzy and amp in tin foil.
Steve
Penelope Stopit said:
Have you tried disconnecting the radio aerial?
No I haven't .. would this create an issue with the ECU firing the fuel pump relay though ?Also the last time I had the centre console out it took about 4 hours of cursing to get it back in, I'm not too keen on taking it out again
spitfire4v8 said:
Penelope Stopit said:
Have you tried disconnecting the radio aerial?
No I haven't .. would this create an issue with the ECU firing the fuel pump relay though ?Also the last time I had the centre console out it took about 4 hours of cursing to get it back in, I'm not too keen on taking it out again
I don't know if the interference through the aerial would trigger the ECU....It was a suggestion
Edited by Penelope Stopit on Wednesday 28th November 12:59
Penelope Stopit said:
Fitting the HID transformer units in metal boxes may solve the problem
Are the HID units expensive or cheap?
There's no makers marks on them, just some voltage info, so i strongly suspect they are cheaper end of the market items. Buying some expensive versions seems excessive especially if it doesn't cure it .. though the chanes are they would be considerably better shielded so probably the way to go. Or my preferred route of some high power good quality filament bulbs with some relays fed by a thick cable from say the back of the starter motor to reduce voltage drop.Are the HID units expensive or cheap?
Edited by Penelope Stopit on Wednesday 28th November 12:56
The owner is on his way down so I can show him his magic car!
spitfire4v8 said:
Penelope Stopit said:
Fitting the HID transformer units in metal boxes may solve the problem
Are the HID units expensive or cheap?
There's no makers marks on them, just some voltage info, so i strongly suspect they are cheaper end of the market items. Buying some expensive versions seems excessive especially if it doesn't cure it .. though the chanes are they would be considerably better shielded so probably the way to go. Or my preferred route of some high power good quality filament bulbs with some relays fed by a thick cable from say the back of the starter motor to reduce voltage drop.Are the HID units expensive or cheap?
Edited by Penelope Stopit on Wednesday 28th November 12:56
The owner is on his way down so I can show him his magic car!
Yes, probably better to fit some decent bulbs and relay them
Englishman said:
Just a suggestion, but have you tried (a) removing the bulbs and (b) disconnecting one transformer at at time to help isolate where the issue is?
I haven't actually run it without the bulbs in, as they run at something like 25Kv I was reluctant to do that. Disconnecting the transformers one at a time makes a difference in that disconnecting the nearside one has more of an effect, but as it's closer to the distributor (where I think the interference is being picked up) that seems likely anyway. The upshot of the customer coming down is that I am going to put it back onto a good quality high output filament bulb set up through relays .
cheers all
Sardonicus said:
Unplug the 2 pin connector from the inductive winding from dizzy to ign module (not module to coil) and see what happens I think this is being used as an aerial and triggering the ign module and hence pulsing the coil it only needs one pulse to tell the ECU to prime the FP 
Does it have the small black square resistor in the Black/White wire that runs from the coil/dizzy back to the ECU?I suggest changing them to LEDs, aftermarket HIDs were band this year as they are usually installed without automatic beam level adjusters but isn’t normally an issue on TVRs as we don’t have back seats or load up our boots.
I’ve personally used good quality HIDs on my Griff trouble free for 5 years with the transformers under the light pods and in the past my MOTer actually commented how much better the light patterns is.
Jools, looks like your going back to 'old' style incandescent lamps now? Guess you could consider/advise converting to LED lamps?
I'd agree - likely it is EMI when the HID 'strikes' the arc....why wouldn't a high voltage across an air gap generate something? The screening, therefore, should have prevented any interference externally?
Can only agree that the EMI must be being picked up by the ign. amplifier wiring.
Anyone else??
Nick
I'd agree - likely it is EMI when the HID 'strikes' the arc....why wouldn't a high voltage across an air gap generate something? The screening, therefore, should have prevented any interference externally?
Can only agree that the EMI must be being picked up by the ign. amplifier wiring.
Anyone else??
Nick
stevesprint said:
Does it have the small black square resistor in the Black/White wire that runs from the coil/dizzy back to the ECU?
I suggest changing them to LEDs, aftermarket HIDs were band this year as they are usually installed without automatic beam level adjusters but isn’t normally an issue on TVRs as we don’t have back seats or load up our boots.
I’ve personally used good quality HIDs on my Griff trouble free for 5 years with the transformers under the light pods and in the past my MOTer actually commented how much better the light patterns is.
hi Steve .. yes resistors (both of them) are present, changed them anyway and no change sadly.I suggest changing them to LEDs, aftermarket HIDs were band this year as they are usually installed without automatic beam level adjusters but isn’t normally an issue on TVRs as we don’t have back seats or load up our boots.
I’ve personally used good quality HIDs on my Griff trouble free for 5 years with the transformers under the light pods and in the past my MOTer actually commented how much better the light patterns is.
As an aside : I've been trying to contact julian bridle for months to give him some money but he doesn't seem to be replying. He built some dual map eprom boards for me and I really want to give him some payment. Can you give him a nudge if you're in contact with him please
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