Diesel tachometer

General information about the first-generation Nissan Maxima in the US. What was the Datsun 810 became the luxury leader Maxima in the US in 1981.

Moderators: plenzen, goglio704, glenlloyd, Nissan_Ranger

Post Reply
User avatar
asavage
Site Admin
Posts: 5329
Joined: 14 years ago
Location: Duvall, Wash.
Contact:

Diesel tachometer

#1

Post by asavage » 14 years ago

Most of the instrument cluster is different, between the gasser and diesel versions. One glaring lack is the tachometer -- diesels didn't get one.

One solution (that I have not tried) is a TinyTach.
Image

Diesel Tiny-Tach™
  • Engine RPM to 19,990.
  • Correct reading regardless of the number of cylinders.
  • Displays RPM when engine is running.
  • Automatically displays run-time hours when engine is shut off (and power is still on).
  • A low cost method of keeping track of engine performance.
  • Standard wire length is 8 feet.
  • Accurate means of setting exact engine RPM for proper operation of diesel engines.
  • Requires vehicle power or external 9 volt transistor battery. (Replace 9 volt battery only once per year.)
  • Has job timer and 2 service timers.
They're $65 (in 2005; $95 in 2013), and use a clamp-on piezoelectric pickup on an injector line.

Image

Apparently, it updates the display every .5 second, and the piezo pickup lead is a coax cable, so you'll not want to cut it unless you're good with soldering up coax.

Looks like a nice unit to me.
Last edited by asavage 6 years ago, edited 5 times in total.
Regards,
Al S.

1982 Maxima diesel wagon, 2nd & 4th owner, 165k miles, rusty & burgundy/grey. Purchased 1996, SOLD 16Feb10
1983 Maxima diesel wagon, 199k miles, rusty, light yellow/light brown. SOLD 14Jul07
1981 720 SD22 (scrapped 04Sep07)
1983 Sentra CD17, 255k, bought 06Jul08, gave it away 22Jun10.

User avatar
philip
Posts: 1494
Joined: 14 years ago
Location: Southern California, USA

Re: Diesel tachometer

#2

Post by philip » 13 years ago

Al ... do you suppose this piezo transducer would work with the Tach-n-Time tool too?
-Philip
Passed 08May2008
My friend, you are missed . . .

1982 Datsun 720KC SD-22

"Im slow and I'm ahead of you"

User avatar
asavage
Site Admin
Posts: 5329
Joined: 14 years ago
Location: Duvall, Wash.
Contact:

#3

Post by asavage » 13 years ago

My guess is: yes, it would supply sufficient output for the Tach-n-Time.

Even if it doesn't, you get a nifty tach :twisted:
Regards,
Al S.

1982 Maxima diesel wagon, 2nd & 4th owner, 165k miles, rusty & burgundy/grey. Purchased 1996, SOLD 16Feb10
1983 Maxima diesel wagon, 199k miles, rusty, light yellow/light brown. SOLD 14Jul07
1981 720 SD22 (scrapped 04Sep07)
1983 Sentra CD17, 255k, bought 06Jul08, gave it away 22Jun10.

User avatar
philip
Posts: 1494
Joined: 14 years ago
Location: Southern California, USA

#4

Post by philip » 13 years ago

asavage wrote:My guess is: yes, it would supply sufficient output for the Tach-n-Time.

Even if it doesn't, you get a nifty tach :twisted:
The nifty tach and transducer together for $65 and/or just a transducer for $25. HMMM. Sure beats Kent/Moore's uptown price of $130 for a thumbwheeled transducer!

I'm going to look further into this. Thank you.
-Philip
Passed 08May2008
My friend, you are missed . . .

1982 Datsun 720KC SD-22

"Im slow and I'm ahead of you"

User avatar
83_maxima
Posts: 423
Joined: 13 years ago
Location: Denver

#5

Post by 83_maxima » 13 years ago

philip wrote: The nifty tach and transducer together for $65 and/or just a transducer for $25. HMMM.
My exact question...

I have read about a similar (looking) unit that uses the "W" signal from the alt. and a signal converter which you have to set - and guess what your idle is. I like this one much better.

Carimbo
Posts: 459
Joined: 14 years ago

#6

Post by Carimbo » 13 years ago

Doesn't the LD25 have a revolution sensor ('82 FSM p. EC-25) that sends signal to the EGR control unit? Could one tap off this signal to drive a simple display?

User avatar
asavage
Site Admin
Posts: 5329
Joined: 14 years ago
Location: Duvall, Wash.
Contact:

#7

Post by asavage » 13 years ago

Sure. Do it! Then tell us how, with a parts list and photos.

I think that $65 for a pre-engineered unit is hard to beat. But if I wanted to screw around trying to adapt an analog tach movement, yeah, the EGR speed sensor on the front of the IP would be a good, linear signal.

I won't build a breadboard circuit if I can buy turnkey for that low of a price. I'm just too busy/lazy.
Regards,
Al S.

1982 Maxima diesel wagon, 2nd & 4th owner, 165k miles, rusty & burgundy/grey. Purchased 1996, SOLD 16Feb10
1983 Maxima diesel wagon, 199k miles, rusty, light yellow/light brown. SOLD 14Jul07
1981 720 SD22 (scrapped 04Sep07)
1983 Sentra CD17, 255k, bought 06Jul08, gave it away 22Jun10.

User avatar
asavage
Site Admin
Posts: 5329
Joined: 14 years ago
Location: Duvall, Wash.
Contact:

#8

Post by asavage » 12 years ago

Carimbo wrote:Doesn't the LD25 have a revolution sensor ('82 FSM p. EC-25) that sends signal to the EGR control unit? Could one tap off this signal to drive a simple display?
Hmmm. I dusted off my trusty TDS210 (for which I paid a cool $995 in 1998, and which has been seriously collecting dust for the past few years. It was a seriously cool piece of equipment back in the day, and I barely know how to turn it on, much less access the menus. I do wish that I'd bought the RS232 interface, but Tektronix wanted something like $300 for it alone -- and the damned 60Mhz leads were $250 each! I really love this 'scope, though. It's got 60Mhz bandwidth, plenty for the stuff I deal with. Please do note the 10 gal. propane tank "equipment stand" I'm using today!):

Image Image Image

[Later edit: this sensor later went open (bad), so this waveform may be incorrect.]

This is what I see at idle (assumed to be ~800 for this exercise: my Strattec vibra tach is eight miles away, my digital Kent-Moore Tach-N-Time is 17 miles away, and my Cole-Parmer optical tachs I have here can't "see" well enough with all the clutter of belts and accessories and such: "~800 RPM" will have to do for now.):

Image

36Hz/800 RPM seems to be 270Hz/6000 RPM; I assume the signal frequency is adqequate. However, the signal amplitude looks pretty low: 300mV at idle, perhaps 1100mV at double that.

Is 0.3v too low a signal for a tach? I haven't tried it, I am only in the "wondering" stage at this point. I have posted a Q to a tach expert on a forum for support of a tach I recently bought.

I'm looking at this OEM rev sensor because there is no external tap on the OEM alternator that will yield enough amplitude either:

(click on image for larger)
Image

Sure, I can open up the alternator and run a wire from upstream of the diode trio to the outside, but that's a lot more work than I'd really like to do. Although VW offered an alternator with a signal tap (the "W" terminal), Nissan did not. So, I'm looking at the LD28 OEM rev sensor.
Last edited by asavage 11 years ago, edited 1 time in total.
Regards,
Al S.

1982 Maxima diesel wagon, 2nd & 4th owner, 165k miles, rusty & burgundy/grey. Purchased 1996, SOLD 16Feb10
1983 Maxima diesel wagon, 199k miles, rusty, light yellow/light brown. SOLD 14Jul07
1981 720 SD22 (scrapped 04Sep07)
1983 Sentra CD17, 255k, bought 06Jul08, gave it away 22Jun10.

davehoos
Posts: 525
Joined: 13 years ago
Location: Karuah Valley,NSW Australia
Contact:

#9

Post by davehoos » 12 years ago

most of the time normal gasoline tacho will work with very low weak signals.

most ignition systems break the ground circuit to fire the coil.factory diesel normaly use a voltage

using a tacho on a ignition system the problem is often noise.they have resisters or diodes to filter the signal.some ignition modules only need a change in voltage to triger a coil.you buy the module to suit rising voltage or falling voltage.leading edge or trailing.

on a toyota camry[SV21] to run an item using the tacho pulse[LPG/cruise control] a amplifier is used.taping into the camry tacho pulse can reduce the signal to other systems used to run the vehicle..

your LD egr sencor is what runs the factory tacho.LD20 i have has no EGR.it may on the last bluebird taxi.LD20II have a pulse of a star like item behind the timing belt on the crank.the older engines all use 6 pulses the LD20II uses 4.

CD20 has the common tacho pulse triggered by the governor driven cog in the IP body.then through a divideby circuit.
as it is on the side of the pump that the linkages are on it cant be used.

RD28 has the same pickup behind the IP drive pulley.
WCJR31 Skyline.3.0 manual.wagon
R31 SKYLINE/Passage GT/PINTARA
LPG Ford Falcon 99-06 93 Disco
Local Shire Southern Zone Mechanic.


User avatar
asavage
Site Admin
Posts: 5329
Joined: 14 years ago
Location: Duvall, Wash.
Contact:

#11

Post by asavage » 12 years ago

This alternator mod has been done for at least three weeks, so I may as well post it. Heaven knows when I'll bolt it in.

The goal was to provide a tach signal whose frequency varies linearly with engine RPM. The Beede tach I purchased on eBay can use an alternator stator signal for this. Now all I need is a stator signal :(

(click on any image for larger)

Disassemble rotor from rear housing, add 1/8" hole:
Image Image


Some 16ga. wire inserted. Note "strain relief knot" :roll: :
Image


Solder it to the nearest main diode. There's plenty of rotor clearance, so the wire does not need precision dressing:
Image

Add a female bullet connector and some RTV to prevent chafing. A grommet would have to be used for thick metal, and I don't have any like that:
Image Image

Crank sheave = 6.5" OD
Alternator sheave = 3.75" OD
Alternator runs (6.5 / 3.75 = 1.73) times crankshaft RPM
Last edited by asavage 6 years ago, edited 1 time in total.
Regards,
Al S.

1982 Maxima diesel wagon, 2nd & 4th owner, 165k miles, rusty & burgundy/grey. Purchased 1996, SOLD 16Feb10
1983 Maxima diesel wagon, 199k miles, rusty, light yellow/light brown. SOLD 14Jul07
1981 720 SD22 (scrapped 04Sep07)
1983 Sentra CD17, 255k, bought 06Jul08, gave it away 22Jun10.

User avatar
asavage
Site Admin
Posts: 5329
Joined: 14 years ago
Location: Duvall, Wash.
Contact:

#12

Post by asavage » 12 years ago

New tach is cool, but 3k real = 3150 indicated. I have an email into Beede Support to suss it.

I don't know where my VE IP governor tops out, but it's waaay up there. Sometimes I'm an angry driver, and I've had this '82 rev'd to the sky on numerous occasions. Buried the speedo on the way home tonight again. I wonder just how fast this Wagon goes -- the OEM speedo is not real useful. Maybe I should open up the cluster and shave the stop peg off of 85.

User avatar
philip
Posts: 1494
Joined: 14 years ago
Location: Southern California, USA

#13

Post by philip » 12 years ago

More decaffeinated, Al. More DEcaffeinated. :shock:
-Philip
Passed 08May2008
My friend, you are missed . . .

1982 Datsun 720KC SD-22

"Im slow and I'm ahead of you"

User avatar
kassim503
Posts: 1027
Joined: 14 years ago
Location: Stony Brook, NY

#14

Post by kassim503 » 12 years ago

Now that is a intense mod!
'83 maxima sedan, l24e, a/t, black

227K SOLD 6/7/2012

User avatar
philip
Posts: 1494
Joined: 14 years ago
Location: Southern California, USA

#15

Post by philip » 12 years ago

kassim503 wrote:Now that is a intense mod!
But it LOOKS so easy! WhodaThunkaThat!
-Philip
Passed 08May2008
My friend, you are missed . . .

1982 Datsun 720KC SD-22

"Im slow and I'm ahead of you"

Post Reply

Who is online

Users browsing this forum: No registered users and 1 guest