Posts ref Alarm wire blowing engines.

[Newera]

Now that fuel pump has been brought into the discussion, and we\'re diverting from the alarm issue, here\'s a thought:

Standard fuel pump on RX-7 is fed with low current, not high current and even as standard there are always voltage fluctuations depending on what the Alternator\'s producing, load on the electrical system, etc. So is an alarm really possibly going to cause a problem with lean running?

Mostly, a healthy alternator should produce at anything from 12.5 to 14.5 volts when opreating normally, so this is what a fuel pump will see, as opposed to 12 V or even less.

I asked Knight Sports about this, are the most knowledgeable people I know in Japan.

They did say a small drop in voltage or current to the fuel pump wouldn\'t cause detonation only a severe drop in voltage & current, caused by something abnormal.

I still think a voltage or current drop to the ECU wouldn\'t cause a drop in voltage to the coil packs either as the ECU only controls the ignition circuit, it doesn\'t feed it directly.

Check with a volt meter at the pump / coils.... That should provide a concrete answer.

Miguel.

[richard cash]

This has reminded me of something that could be potentially very important and something i forgot to add. Does say having massive amps and subs in a car on full pelt mean that a voltage drop could happen somewhere else? I remembered when i was in my car the music was up loud and i have about 2KW RMS of power. Could this have reduced the voltage pruduced in the alternator enough to cause a problem to other components??

[iaint]

This has reminded me of something that could be potentially very important and something i forgot to add. Does say having massive amps and subs in a car on full pelt mean that a voltage drop could happen somewhere else? I remembered when i was in my car the music was up loud and i have about 2KW RMS of power. Could this have reduced the voltage pruduced in the alternator enough to cause a problem to other components??

AFAIK big audio installs often need a second battery and big capacitors to help with the current drain the bass inflicts on the car\'s system.  I\'ve seen badly done installs dim the main lights when the bass really kicks out so I would think it\'s a significant possibility (or probability) that big ICE could cause enough of a drain to cause you huge problems!

[cjr]

[I still think a voltage or current drop to the ECU wouldn\'t cause a drop in voltage to the coil packs either as the ECU only controls the ignition circuit, it doesn\'t feed it directly/QUOTE]
you are correct in that a voltage drop to the ecu will not cause a voltage drop to the coils and ignition circuit. The reason being that the ecu sends a signal to the ignitor that recives it\'s power source just as the coils recive ther power source from the ignition switch via the black and white wire.
These are my personal veiws
Chris

[bnaellis]

You test enough fuel pump on fd\'s and it is quite apparent that there is hardly ever 12 volt getting to the pump. You rewire fuel pumps on a fd and you will see that increasing pump voltage by 1v change the afr buy approx 1 whole point e.g 10.7 to 9.7 afr. There is no reason to suspect that losing 1 volt to the fuel pump would have the same effect on afr say 10.7 to 11.7 afr.
Depending on boost, fuel, timing it is very likely low voltage to the fuel pump could cause detonation.

[iaint]

You test enough fuel pump on fd\'s and it is quite apparent that there is hardly ever 12 volt getting to the pump. You rewire fuel pumps on a fd and you will see that increasing pump voltage by 1v change the afr buy approx 1 whole point e.g 10.7 to 9.7 afr. There is no reason to suspect that losing 1 volt to the fuel pump would have the same effect on afr say 10.7 to 11.7 afr.
Depending on boost, fuel, timing it is very likely low voltage to the fuel pump could cause detonation.

Is the bold bit supposed to read differently?  i.e. There is no reason not to suspect[/B] that

[bnaellis]

Is the bold bit supposed to read differently?  i.e. There is no reason not to suspect[/B] that

Yes my bad, should of had an early night.