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tach, fuel injector?


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equate 
Copper - Posts: 118
Copper spacespace
Joined: March 07, 2005
Posted: March 24, 2010 at 11:52 AM / IP Logged  
I knew some installer use fuel injector for tach.how to use it? wrap some loop on fuel injector then connect it to RS? or cut out fuel injector ? I am afraid that hurts the car...
I see injector likes this picture
tach, fuel injector? -- posted image.
there is no electrical wires on it. Anyone can share your experience?
Thanks
sneakycyber 
Silver - Posts: 413
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Joined: September 13, 2005
Location: United States
Posted: March 24, 2010 at 12:59 PM / IP Logged  
An Electronic fuel injected car has wires running to each injector which causes it to open and close during the intake cycle. This on/off cycle allows it to be used as a tach input telling the RS that the vehicle has been started.
tedmond 
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Gold spaceThis member has been recognized as an authority in Mobile Security and Convenience. Click here for more info.spacespace
Joined: January 06, 2007
Location: Ontario, Canada
Posted: March 24, 2010 at 3:14 PM / IP Logged  

you can use, tach, fuel injector, camshaft sensor, those all work.

for fuel injectors, often you want to tap into the wire that is uncommon.

Ted
2nd Year Tier 1 Medical School
Still installing as a hobby...pays for groceries
Compustar Expert
howie ll 
Pot Metal - Posts: 16,466
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Joined: January 09, 2007
Location: United Kingdom
Posted: March 24, 2010 at 5:36 PM / IP Logged  
And if you're still doing that Kia, pull the inst. panel and pick up the tach if there is one.
oldspark 
Gold - Posts: 4,913
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Location: Australia
Posted: March 24, 2010 at 6:33 PM / IP Logged  
The injector signal may have to be scaled - they may fire once, twice or multiple times per cycle - eg, once per 2 revs of sequential, once per rev if "wasted" (like a spark), or if bank fired - up to the spark rate of the engine (eg 4 or 2 times per 2 revs for a 4cyl, 6 or 3 for 6 cyl, etc).
But I'd recommend using existing tacho wires as Howie suggested, else a splug/ignition signal because many injectors are fired at fixed timing until the engine starts - eg, every 12mS (though that is only interpreted as being up to about 330RPM for an 8-cyl engine).
But injectors can change their firings per rev (RPM) whereas a spark only occurs a set number of times (multi-spark systems excluded). EG - a true sequential injector might normally fire once per 2 revs, but might increase to once per rev under high load/power to get more fuel in (if the injector does not have the required capacity).    
Things like that drive people nuts - especially those fixed in the traditional ways of engine and automotive operation.
Skip the rest unless you want extra FYI to the above.....
Old tacho's merely counted from the distributor points (spark) which fired at half the number of cylinders (ie, an 8 cylinder 4 stoke fires 8 times per 2 revs, hence 8/2 = 4 times per rev (RPM)).
But these days many are wasted spark (4 dual-coils feeding 8 cylinders) which is the same number of sparks but distributed over 4 coils (and each splug sparks twice as often as a traditional points/electronic distributor).
Then there is sequential which tends to mean one coil per splug in spark terms which translates to one injector firing per 2 engine revs.
But like spark, even single coils (like COPs - Coil On sPlug) can be fired in wasted (2x2 mode) or batch....
It is common for engines to fire splugs on both BTDCs (Before Top Dead Centres) for environmental reasons etc.
It is not uncommon for injectors to do similar. In fact some cars trigger ALL injectors at the same time (despite being in 2, 3 or 4 banks of 2 etc injectors).   
Yep - it drives many nuts!
equate 
Copper - Posts: 118
Copper spacespace
Joined: March 07, 2005
Posted: March 25, 2010 at 1:23 AM / IP Logged  
howie ll wrote:
And if you're still doing that Kia, pull the inst. panel and pick up the tach if there is one.
Do you have pic for this panel? Sorry that I am new on this.
Thanks
equate 
Copper - Posts: 118
Copper spacespace
Joined: March 07, 2005
Posted: March 25, 2010 at 1:30 AM / IP Logged  
oldspark wrote:
The injector signal may have to be scaled - they may fire once, twice or multiple times per cycle - eg, once per 2 revs of sequential, once per rev if "wasted" (like a spark), or if bank fired - up to the spark rate of the engine (eg 4 or 2 times per 2 revs for a 4cyl, 6 or 3 for 6 cyl, etc).
But I'd recommend using existing tacho wires as Howie suggested, else a splug/ignition signal because many injectors are fired at fixed timing until the engine starts - eg, every 12mS (though that is only interpreted as being up to about 330RPM for an 8-cyl engine).
But injectors can change their firings per rev (RPM) whereas a spark only occurs a set number of times (multi-spark systems excluded). EG - a true sequential injector might normally fire once per 2 revs, but might increase to once per rev under high load/power to get more fuel in (if the injector does not have the required capacity).    
Things like that drive people nuts - especially those fixed in the traditional ways of engine and automotive operation.
Skip the rest unless you want extra FYI to the above.....
Old tacho's merely counted from the distributor points (spark) which fired at half the number of cylinders (ie, an 8 cylinder 4 stoke fires 8 times per 2 revs, hence 8/2 = 4 times per rev (RPM)).
But these days many are wasted spark (4 dual-coils feeding 8 cylinders) which is the same number of sparks but distributed over 4 coils (and each splug sparks twice as often as a traditional points/electronic distributor).
Then there is sequential which tends to mean one coil per splug in spark terms which translates to one injector firing per 2 engine revs.
But like spark, even single coils (like COPs - Coil On sPlug) can be fired in wasted (2x2 mode) or batch....
It is common for engines to fire splugs on both BTDCs (Before Top Dead Centres) for environmental reasons etc.
It is not uncommon for injectors to do similar. In fact some cars trigger ALL injectors at the same time (despite being in 2, 3 or 4 banks of 2 etc injectors).   
Yep - it drives many nuts!
I dont really understand this post.
Is there AC output on fuel injector during cranking?
equate 
Copper - Posts: 118
Copper spacespace
Joined: March 07, 2005
Posted: March 25, 2010 at 1:42 AM / IP Logged  
tedmond wrote:

you can use, tach, fuel injector, camshaft sensor, those all work.

for fuel injectors, often you want to tap into the wire that is uncommon.

I couldnt find the tach wire on this car. I got Crankshaft Sensor on engineer and testing voltage AC 5V. I was installing VIPER 5901 on it.
When I was trying to do tach learning, it was failed. Holding on CONTROL button, LED didnt turn on.
is it wrong tach wire?
howie ll 
Pot Metal - Posts: 16,466
Pot Metal spacespace
Joined: January 09, 2007
Location: United Kingdom
Posted: March 25, 2010 at 3:43 AM / IP Logged  
I'm beginning to wonder if you are capable of doing this. Asking me for a picture of inst panel removal, are you kidding? Install work 101! Most oriental cars use a printed circuit to distribute the electricity to the various gauges, warning lights etc. If it has a rev counter there will be 4 terminals at the rear, ign, ground, illumination and TACH. By the way wrapping wire round it won't do it, that's inductive follow any of these posts, remove insulation wrap your PURPLE / white wire round it, test. If it works solder and insulate. For YOUR purposes all of the above mentioned methods work and before Oldspark reams me yes it's AC from YOUR point of view. Set DMM to 20VAC, should read between 4-7 volts as you increase the revs.
oldspark 
Gold - Posts: 4,913
Gold spacespace
Joined: November 03, 2008
Location: Australia
Posted: March 25, 2010 at 3:49 AM / IP Logged  
Crankshaft sensors are often reluctors which put out an AC signal. Just rectify it.... etc.
equate wrote:
Is there AC output on fuel injector during cranking?
AFAIK no injectors are AC - they are all DC.
I was saying that unlike spark, injectors may change the number of times they fire per engine cycle (ie, per 2 revs). Hence you are probably better off sensing spark.
And like spark, they might fire 1, 2, 3, 4 etc times per cycle.
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