tach wire, hmm, i,m scared

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dburnash

Member - Posts: 7

Joined: March 04, 2009

Location: Michigan, United States

Posted: March 08, 2009 at 2:17 PM / IP Logged

Ok I got the galaxy R.S insatalled on the 06 xterra and everything works as it should. ( a feat for me). Im using the tachless option. The car starts fine when warm but tries three times and then gives up when cold. i,m assuming that I,m going to need the tach hooked up and the tach option enabled. Ive read what i could find on the tach input and frankly dont know what a 7x,24x, or camshaft position sensor even looks like. Only option I can find is tapping an injector wire. (any one that is NOT the common as i understand it) Is it really safe to just hook into one of my injector wires? Solder, butt connector,scotch lock,splice? sounds scary to me. any advice (or reasurance) is appreciated. thanks Mike

loneranger

Copper - Posts: 572

Joined: December 28, 2008

Posted: March 08, 2009 at 2:59 PM / IP Logged

dburnash wrote:

The car starts fine when warm but tries three times and then gives up when cold.

Before it fails, does it just crank? If so, your issue is crank time and tach input would solve this issue, in cold weather. It may also indicate your vehicle needs a tune-up.

Temporarily, splice and tape. Test the situation. If it conceeds, solder and seal. Otherwise, remove; seal; and start over with another tach source.

However, I had an issue with tach input, in cold weather. It was related to shutdown from over-rev protection. The DEI Viper 5301 seems to consider 1500 RPM over 800 RPM, as over-revving. I switched to voltage-sensing and solved the issue. However, I'm now without over-rev sensing and a possible stall situation. I have not tried vitual-tach, for installations, as I don't fully understand its' design and I don't have a Bit-Writer. In cold or warm weather, my vehicle only needs ~.5 second crank time.

Ideal - cmon dude, add to topics in a useful manner, not stuff that is obvious.

Story - Phzzzt! Hey, what happened?! ... Isn't it obvious?

Moral - Never dismiss the obvious.

dburnash

Member - Posts: 7

Joined: March 04, 2009

Location: Michigan, United States

Posted: March 08, 2009 at 3:57 PM / IP Logged

Yes it just attepts to start three times then fails. i thought this might be a problem. When we got the car (one week ago) I noticed on cold days it seemed to crank a bit longer than any of our other vehicles before starting. Its only got 15,000 miles so i believe it is in decent tune.

One other question. When cold, on first start up, the motor Runs pretty high rpm and then slowly comes down ( inherent on this vehicle from what Ive been told) So when I program the R.S for tach learning should i initiate the RPM learning from cold start where engine races ,or when warm where engine starts and idles normally?

Thanks for the help, Mike

loneranger

Copper - Posts: 572

Joined: December 28, 2008

Posted: March 08, 2009 at 4:14 PM / IP Logged

dburnash wrote:

When we got the car (one week ago) I noticed on cold days it seemed to crank a bit longer than any of our other vehicles before starting. Its only got 15,000 miles so i believe it is in decent tune.

A possible faulty vehicle cold-air sensor might cause that issue, but doubtful based on the following quote.

dburnash wrote:

When cold, on first start up, the motor Runs pretty high rpm and then slowly comes down ( inherent on this vehicle from what Ive been told).

That's not entirely odd, in extreme cold weather climates.

dburnash wrote:

So when I program the R.S for tach learning should i initiate the RPM learning from cold start where engine races ,or when warm where engine starts and idles normally?

There in lies the catch-22. If programmed too high, the R/S may over-crank(low-idle), after true idle is achieved. If programmed too low, the R/S may over-rev protect(high-idle), before true idle is achieved. This all depends on the R/S design parameters. Test and proceed at best.

Ideal - cmon dude, add to topics in a useful manner, not stuff that is obvious.

Story - Phzzzt! Hey, what happened?! ... Isn't it obvious?

Moral - Never dismiss the obvious.

KPierson

Platinum - Posts: 3,527

This member consistently provides reliable information

Joined: April 14, 2005

Location: Ohio, United States

Posted: March 08, 2009 at 4:50 PM / IP Logged

In most Nissans you can tag the fuel injector inside the vehicle - they like to mount their ECUs under the passenger side dash. I've never worked on an Xterra so I'm not sure where it is. I always recomend soldering the fuel injector wire - there is no concern with tapping in to the fuel injector as the remote start is using a high impedence input to monitor the signal - it won't change the signal in any way.

Is your 2nd starter wire hooked up? I would think that the car should start by three attempts, even when cold. I have a Honda Accord that doesn't always start the first time when cold (no tach wire) but on the 2nd attemp it always starts and actually drags the starter just a bit.

You can download the service manual off of a Nissan forum and find the schematic for the ECU - this will allow you fo find a fuel injector signal right at the ECU and not at the motor.

Kevin Pierson

mikvot

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Joined: December 19, 2006

Location: Missouri, United States

Posted: March 08, 2009 at 4:59 PM / IP Logged

I would definately make sure your second starter wire is hooked up as KP already

mentioned. Without this wire hooked up properly you will always have problems when it's cold.

Chris Luongo

Platinum - Posts: 3,746

Joined: May 21, 2002

Location: Massachusetts, United States

Posted: March 08, 2009 at 5:34 PM / IP Logged

No reason to be afraid to splice into an injector or coil wire at the motor, no.

You'll see that the six injectors (or coil packs) will have probably three wires..........two of the wires will always be the same color from one injector to another. You want to use the wire that's NOT always the same color, the always-different wire.

Again, don't be scared, but when you bring the wire through the car's firewall under the hood, be sure you do it in a way that it won't short out to the car's body metal through the firewall.

Run the wire along with some of the factory wiring to make it to the top of the engine where you'll connect to the injector. Don't just drape the wire over hot parts where it could melt.

Take into account that the engine vibrates and moves back and forth in its motor mounts. That's why it's best just to follow some of the factory wires and zip-tie onto them.

Everyone will have debates all day about which wire connection method is best.......some people us scotch locks, some don't. And everyone's very firm in their opinion.

However, I think most installers would agree that scotch locks and t-taps are not corrosion resistant. Even if you use them inside the car, they're not very reliable under the hood.

I would open up the factory wire, splice your new wire into it, solder if you're able to, and wrap it with some good electrical tape. And then a zip-tie over the tape never hurts.

Also, I did find this information for you:

Tachometer LIGHT BLUE (AC) AT ECM MODULE ON PASSENGER FENDER

dburnash

Member - Posts: 7

Joined: March 04, 2009

Location: Michigan, United States

Posted: March 08, 2009 at 5:48 PM / IP Logged

Yes I have the second starter wire connected. From what I understand this wire is for the cold start system. I have the manual and have located the ECM and the pins for the injectors. The ECM is located in the engine room behind the washer bottle so I would have to run another wire through the fire wall anyways. prolly easier to catch one of the injector wires. Besides If I was scared of tapping an injector wire Im sure I wont feel good rooting around in the ECM harness. as loneranger said I absolutely hate that " phzz.. hey what happened?" I guess since I,m this far the tach wire is something I just have to do. Think Ill try tapping the INJ. wire and starting with the engine warm for tach learn to try and avoid the overcrank. Ok here goes!

Thanks for eveyones help.

P.S this site is freakin great! When I was younger there was'nt the option of seeking help like this. Back then it was off to the library and hope you could find what you were after there!

dburnash

Member - Posts: 7

Joined: March 04, 2009

Location: Michigan, United States

Posted: March 08, 2009 at 5:59 PM / IP Logged

thanks for looking up that info chris. Appreciated. Mike

loneranger

Copper - Posts: 572

Joined: December 28, 2008

Posted: March 08, 2009 at 6:21 PM / IP Logged

dburnash wrote:

Back then it was off to the library and hope you could find what you were after there!

Ahh, the library days. That was before the intarweb.

Ideal - cmon dude, add to topics in a useful manner, not stuff that is obvious.

Story - Phzzzt! Hey, what happened?! ... Isn't it obvious?

Moral - Never dismiss the obvious.

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