I'm attempting to rescale my Tachometer in our VQ Sentra project.. The 6 cylinder signal with the 4 cylinder Tach, makes the guage peg out past 9K rpm! I was hoping that there would be a potentiometer inside the cluster that I could adjust.. some of the older Nissan clusters had this feature.. but, no such luck with this car.. I'm thinking about unsoldering the motor, and soldering in a Maxima piece, since it would have the correct windings for the 6 cylinder signal.. However, would there be a way to solder in a potentiometer, or some other electrical part, to make this signal adjustable?

Travis

 

http://www.terf.com/TachChangerPage.htm

Something like this could also be used to manipulate shift points on a TCM.

 

Thanks man..

 

Being Auto, I would love to be able to change my shift points... Just another thing to add to the list.

 

Then all you do is intercept the Tach wire going to the TCM and adjust it to put out a lower RPM 'signal'. That way your TCM will shift at a higher 'actual' rpm than it does now.

I would recommend that anyone who uses this for that purpose should wire it up to only take over RPM to TCM signal at WOT so it won't adversly affect normal daily driving.

 

Look around to see if you can find something less expensive. I have been trying to find something like that for awhile now. I only found that one after you asked.

 

Jime has a project going to change AT shift points also. Last I talked to him a couple weeks back he hadn't gotten far with it though since he didn't have the engine back in yet.

 

On the subject of Tach's... What's the procedure for installing an aftermarket tach in a 5th Gen...? Someone was telling me about a resistor that has to be soldered between the power wire feeding the tach, and the signal wire going to the tach, from the ECU.

 

Matt, changing the RPM signal going to the TCM does not change the shift point. The TCM is using more than just the RPM to determine the shift. Been there done that a couple of months ago. Using a digital pulse adjuster I changed the RPM by over 2k up and down and it made absolutely no difference in the shift even though the tach registered the change. It is somewhat more involved than that, I don't have it nailed down yet but working on it.

The RPM signal comes from the ECU to the TCM then to the tach so any change in the signal to the TCM will be reflected on the tach.

 

But what did you try this on? It does not work on the 2k2+ because they use a CAN line to feed the TCM. It would only work on the earlier cars if you intercept the tach wire that feeds the TCM.

 

4th Gen, 2 different 95's. Didn't try it on the 2k2.

Its a great idea, I thought it would work too.

Apparently it does work on some cars, just not the maxima.

 

That company also sells a device tore cal. the speed signal going to the TCM.

By the way, what device did you use and where did you get it from? I want a less expensive (than this $150 device) way to calibrate my OE 2k2 Tach.

 

is it possible that the TCM takes other things into account instead of RPM. perhaps the speed and the throttle position? like if ur goign at a certain speed and the throttle is opend to a certain point the tranny will make its decision.

 

It actually uses 3 inputs, TPS, RPM and Speed sensor. Thats why its a little more complicated.

Matt mine cost over $300 with the digital controller, so you don't want one of them just to adjust the RPM.

 

Do u know if the TCM can be programed through software? or its built in hardware that cant be changed?

 

Apparently it can be programmed because JWT will modify your TCM to raise the shift point for a paltry $595. Lot of bucks and you have to live with the shift point you can't change it.

 

Have you seen one of these JWT TCMs, or the inside of your TCM? If so, do you have any pics?

 

No I haven't seen one, I didn't even know they existed until Alex told me about them. I called them up and asked the price and if it did anything else besides raise the shift point. They said 7k shift point that cannot be adjusted and thats all for $595.

 

And I bet some poor sap has paid that price too. You can almost buy a complete aftermarket TCM for that much.

http://www.powertraincontrolsolution...content-4.html

 

LOLz


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