Posts ref Alarm wire blowing engines.

[kev-yorks]

Run a microtech Matt you get a new loom with it and about £12 for all the plugs to solder on.
Kevin

[88GT-R]

Run a microtech Matt you get a new loom with it and about £12 for all the plugs to solder on.
Kevin

But you still need to cut into the std ignition wireing, same as the alleged alarm farce, hence \'potentialy\' running the same risk...A point i made earlier.....but peoples heads were still stuck up their***** Happy days :Thumbs-up

J

[oldone]

But you still need to cut into the std ignition wireing, same as the alleged alarm farce, hence \'potentialy\' running the same risk...A point i made earlier.....but peoples heads were still stuck up their***** Happy days :Thumbs-up

J

:eek  hehehehehehehehehe.............:wiggle

[Jonathan_F]

My tuppence:

I fitted a clifford concept 500 to my Rex TTurbo. Afterwards I had problems with missfire and eventually the engine had to be removed.

Both the ignition and fuel pump looms were cut and isolating relays installed. The Clifford wiring was of similar x-sectional area.

My hypothesis: The mazda ignition and fuel circuits require larger current flow than most and both looms are close to the limit of their ability to provide adeqate voltage to their respective systems. By adding a relay and extra lengths of wire, these limits are surpassed. The result: lower fuel pressure and poor spark.
The fuel supply can be \'tuned for\' but weak spark leads to incvomplete combustion and carbon build up. Hot spots ensue and detonation occurs.

My solution: fitting secondary relays and direct supply from the battery to both these areas. Fused of course.

Please can I have your comments as to the validity of this?

Jon

[TRex]

Me thinks people need to read up on how Automobile electrics work and more importantly, the Coils and Ignition system!

[antnicuk]

i spoke to a friend of mine about this who used to fit alarms for a living, mainly clifford.  He is also an auto electrician.  When he used to fit alarms a few years ago the wiring and relays supplied were of a much better quality and more substantial but now like most things, the relays are cheap and the wiring thinner......  just something else to think about

[Prof]

Me thinks people need to read up on how Automobile electrics work and more importantly, the Coils and Ignition system!

I\'m guessing some people have !:o
 
Thing is I sit in a room full of electronics gear whilst I type this - including a low resistance meter - very accurate for low sub 0.1 Ohm readings on bits of wire, and there is some truth in the alarm wire being too small !
 
The wire section of the average alarm would give cable rated for 20A tops.  The thickness of wire in the feed to the main relay is about 4 x the area - good for 80A easily.  So you either double or triple up on the wire, or use an off board relay to switch it.  Even if you used thicker wire, the relay and the tracks on the alarm PCB may not be much better.  Most alarm\'s are rated at 30A max and are fused accordingly.
 
And for those wanting to know a bit more about coils:
 
A coil is a transformer - it has a primary - usually wired with thicker gauge wire of a few turns, where a high current low voltage feed will be transformed into a high voltage low current output.  The secondary has many more turns of smaller gauge wire, as the current output is much less.  The energy of the spark will be determined by the voltage x current and the duration of the spark.  You can prolong the duration of the spark by stretching the pulse that\'s sent to the coil - usually done with an ignition amp or by the ECU in some cases, you can improve the current supply to the coil by storing energy in either capacitors or inductors and then discharging that - the CDI or ID type ignition amps.  These devices often have intelligence inbuilt to supply multiple sparks in quick repetition at low RPM, and a single powerful spark at high RPM.
 
So you can weaken the spark if you reduce the voltage, or the current that\'s provided to the coil, unless you use an ingnition amp which is usually suplied power on a dedicated feed from the main fuse or battery, or insure that the leads in the circuit are the lowest resistance they can sensibly be - in other words keep these cables thick.
 
I think the point of this thread is to educate people to a very real danger that may exist with certain alarms and the way they are fitted - by all means ingore it and if you think you know better then good for you - but be sure of your facts on this - I know I am, and I know what I will be doing on my engine loom when I wire in the eManage.

[88GT-R]

Prof,
What you have written is true, and no one should argue it. The point is this. DETONATION is not caused by a weak voltage supply. A weak/drawn down voltage will affect the ignition system, as you and others have said. Crap wireing ontop of Mazda wireing will have an effect on voltage, but this fact does not constitute a reason for detonation. Most are missing the excuse behind the reasoning.

[Prof]

You\'re right John - not detonation, but it could lead to unburnt material, carbon and then pre-ingition.  The results can end up being the same
 
From what I know - detonation is the result of running too lean, too hot, too higher intake temperature or too advanced timing.  All these factors tend to work together - if you up the boost, then the intake temps go up, and also more air is coming in - if there isn\'t fuel to match it, then you run too lean, and things then get too hot as well !
 
One problem with a weak spark, is that if either the leading or trailing plugs didn\'t fire well, then the mixture tends to burn unevenly as the rotor moves around passed the \'pinch off\' point and the mixtures are re united again.  Rotaries will run on just one set of plugs, but the burn is uneven and \'lumpy\', which is why Mazda put 2 in.  Is it possible that resulting combustion could give a more violent burn and produce higher pressure waves on the tip seals ?  This isn\'t my area of expertise - need someone who knows about burn rates and pressure waves and so on...

[TRex]

Quick question Proff,

 Does a \'Spark Plug\' fire a different Spark(low/high volt/weak/strong) at Idle than it would at High RPM?

[88GT-R]

Quick question Proff,

 Does a \'Spark Plug\' fire a different Spark(low/high volt/weak/strong) at Idle than it would at High RPM?

OOOOOOOOOOOHHHHHHHHHHHHH

[Prof]

That depends
 
If your using an ingnition amp then it probably will be set up that way - the Crane cams do this - multi spark at idle and low rpm - single juice spark above about 2k.
 
For normal setups - where the ECU is firing the coils - the duration of the pulse sent to the coils can be reduced at higher RPM, potentially giving lower spark energy.  Coils have a working frequency range - the coils in cars are no different, so there must be a theoritical max RPM before the problem becomes bad.  Without testing this I don\'t know what that would be...

[88GT-R]

You\'re right John - not detonation, but it could lead to unburnt material, carbon and then pre-ingition.  The results can end up being the same
 
From what I know - detonation is the result of running too lean, too hot, too higher intake temperature or too advanced timing.  All these factors tend to work together - if you up the boost, then the intake temps go up, and also more air is coming in - if there isn\'t fuel to match it, then you run too lean, and things then get too hot as well !
 
One problem with a weak spark, is that if either the leading or trailing plugs didn\'t fire well, then the mixture tends to burn unevenly as the rotor moves around passed the \'pinch off\' point and the mixtures are re united again.  Rotaries will run on just one set of plugs, but the burn is uneven and \'lumpy\', which is why Mazda put 2 in.  Is it possible that resulting combustion could give a more violent burn and produce higher pressure waves on the tip seals ?  This isn\'t my area of expertise - need someone who knows about burn rates and pressure waves and so on...

Once again you are right, but in this detail, ie the great alarm debate, the engine was new and barely run in. Cabon build up is negligable.
The second sparkplug\'s main requirement is in a slightly fuller burn, to improve emmissions.
Cheers,
J

[BlitzBoy]

question about plugs ,does a spark get blown out at high boost if its weak?

[88GT-R]

That depends
 
If your using an ingnition amp then it probably will be set up that way - the Crane cams do this - multi spark at idle and low rpm - single juice spark above about 2k.
 
For normal setups - where the ECU is firing the coils - the duration of the pulse sent to the coils can be reduced at higher RPM, potentially giving lower spark energy.  Coils have a working frequency range - the coils in cars are no different, so there must be a theoritical max RPM before the problem becomes bad.  Without testing this I don\'t know what that would be...

Ignition Dwell time is adjustable on most aftermarket ecu\'s, allowing the mapper the ability to adjust charge time.

J