getting tach at coil or injectors

Hey guys,

I seem to find it increasingly harder and harder to get a good tach singal and have to do remote starts by voltage sensing.   I keep hearing people saying go to the coil or an injector but have no idea where i would look to even tap into for that. Any info on tapping into a coil or injector would be great. Especially if you got pictures you could send my way. Thanks Alot

-Mike

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Driving a Bagged, Caddied 02 s10

When tapping into a fuel injector you first need to know what they look like.

On a front wheel drive car they will be located from left to right on the front and rear of the engine.

On a rear wheel drive they will be located from front to back on both the left and right side of the engine.The are located above the spark plug locations.There are almost always 2 wires comming off of the injectors.Each injector shares 1 wire with the same color and each injector has an odd color wire. use the odd color wire.For example, a four cylinder engine having 4 injectors,

injector 1, one wire is red and the other is blue

injector 2, one wire is red and the other is green

injector 3, one wire is red and the other is white

injector 4, one wire is red and the other is yellow

On injector 1 you would use the blue wire for the tach signal.

on injector 2 you would use the green wire for the tach signal.

and so on,

Hope this helps.

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MECP certified (If it really means anything)
Jeremy

yup it does.. now to start testing on my own cars and learning to locate them..

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Driving a Bagged, Caddied 02 s10

Can't seem to get a stable tach voltage on a 2002 nissan sentra. I used the injectors, but im getting much higher readings, and no change with the rev of the engine. On the sentra, the common color is BLACK/ red so I tried testing all the odd colors on each injector. I also went into the instrument cluster with the color described and didn't get a good signal there either. Anyone know where the PCM is at on a 1.8L?

AC 200.

Cant figure it out, i probed 6 wires on the injectors, I connect my black end of multimeter to ground, and probe with red, I get 30 everytime.

Take the RED lead to 12 volts and the BLACK lead to the target wire. You will get a reading from 1.0 +, works for me everythime this way.

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Jeff
Velocity Custom Home Theater
Mobile Audio/Video Specialist
Morden, Manitoba CANADA

is that really how ur supposed to meter ac wires?

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Driving a Bagged, Caddied 02 s10

THat's one way of doing it. Because it's AC it doesn't matter wether or not the leads are on ground or 12 volts, but I always use 12 volts on the red lead and the target wire for the black lead. If I can find the thread from last year, I'll link to it, but there was a good discussion on how to meter for a tach with the DMM

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Jeff
Velocity Custom Home Theater
Mobile Audio/Video Specialist
Morden, Manitoba CANADA

"I seem to find it increasingly harder and harder to get a good tach singal and have to do remote starts by voltage sensing."

Welcome to the club! I agree it is getting tougher to find a good clean tach signal. Luckily the voltage sensing reliability is also getting better and better IMO. We have used tach inverter/boosters on occasion and they seem to clean up the signal and work fine.

Unfortunately even using the coils and injectors on some newer vehicles isn't the best way to go because the signal just isn't clean enough for proper operation. Not to mention the risk involved. I'm not sure what happens when you ground out one of the wires on the injector or the coil, but I'm sure it's not pretty.

By the way most newer vehicles DO NOT have a common wire at the injectors you basically have to meter the 2 wires or take a good guess.

For testing I use the black lead to ground and the other lead to the wire since it is AC it doesn't make a difference either should work it's just whatever your preference is.

Good luck,

Mike

^^^^^how do you know that most newer cars DO NOT have a common wire at the injectors?

what is "common" wire is, exactly, to you?

if theres no common wire at the injectors, wouldnt that be un-efficient to relay both signals, (-)(neutral) and (+)(hot) at the same time?

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Houston,TX
"The two most common elements in the universe are H+ and stupidity" (Ellison).

Let me clarify.. When I said most newer cars don't have a common wire at the injector, I mean strictly on the color of the wires themselves, not the function. Someone else mentioned there will be one on every injector that is the same color wire, that's not the case on a lot of the newer vehicles. Sorry if I mislead anyone.

Mike

oh common colors.... i got you....NowIKnow

btw, by interpretation of common wire, it meant common grounded. so one wire is ground and teh other is pulse by duration dependin on the computer.

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Houston,TX
"The two most common elements in the universe are H+ and stupidity" (Ellison).