taco recalibration

[cuh8er]

Have a HZJ75 landcruiser fitted with a 1UZ and am just wondering what's the best way to correct the taco? Is there an off the shelf box of tricks I can buy?

thanks

 

[Zuffen]

A Jaycar speedo correcter would work just as well on the tach input as a speed input.

Have you checked the tacho to see if it adjustable?

Many tacho mechanisms go into different dashboards that may need 4/6/8 cylinders. Quite often there is a small switch or simillar to change from one to the other.

If this is the case set it or 4 cylinders and you should be looking good.

 

[cuh8er]

Cheers for the reply Rod,
Haven't checked for adjustability in the current tacho, but I would be very suprised if it was. These things only ever came out with a six so I doubt Toyota built in some adjustability. Worth a check though.

The Jaycar unit would be great, but I have nothing to check it's accuracy. In other words, when I set it up, how will I know if the 3000 rpm I read on the tach is actually 3000rpm? I was hoping to find something that was purpose built to take the UZ pulse/rev value and scale it to suit the Landcruiser pulse/rev value. No room for error this way, but am I asking for too much?

Cheers

 

[Peewee]

The stock tacho's aren't highly accurate over the whole range, so I wouldn't worry about it being 100% correct.

Either way, if you get the Jaycar one set it to 50% increase and it should be right.
The are pretty on rapid changes though. I've got the MkI speedo corrector on my car (as a speedo corrector) and on a hard launch the speedo takes a couple of seconds to start reading, and then is about 1/2sec behind. It's only really noticable during very rapid changes in speed.

I don't know how well it will go with a tacho though. The frequency is much higher so the response rate could be faster.




A lot of stock Toyota tacho's have an adjustable pot, because they all don't read identical from the factory.

Borrow a signal generator and a 4cyl tacho from someone and get it to generate 6000rpm. Then set your tacho to match the 4cyl one.
Its best done at high rpm because 100rpm error at 1000rpm will be 600rpm error at 6000rpm.


I hope all this makes sense.

 

[sideshow]

i do alot of 1hdts into landcruisers
what was yr original enigne
there is a trick to getting these accurate if the original enigne was a old diesel engine

now if the old enigne was 1hd or something the tacho signal comes from the injection pump
well this signal is way more than the 4cly signal the 1uz has

u might have to multiply the signal by 5 or 8 or 10 times
not sure the jaycar unit can do it as i dont trust it

when i do these i run a special signal converter box then i modify it cause in std form can only multiply by 3 ish
i mod it to either 5 or 8 multiplication depending what u need
then this signal is still not ok for the landcruiser tachos so then i fit a signal booster
anyway all up it costs around 350 just to get the factory ones working

i think yrs is an older landcruiser anyway
so best thing to do is rip cluster out and get tacho modifed to suit a 4cly
just look for an instrument guy in yr area
but make sure u tell them the signal is a weak efi 4cyl signal



pee wee is right bout factory tachos not being linear
but since desiels dont rev much past 5
we set the rpm accurate around 3000 cause thats most of yr driving

but if u do get tacho modified then it should fix the prob
so if u want to get factory tacho working its not cheap

if yr tight ass just buy and aftermarket 100 dollar job from super cheap

heheheheeh

 

[cuh8er]

Thanks guys good info.
Sideshow, the landcruiser originally had a plain old 1HZ in it, and is late 1996. Will I need one of your flash converters? If I use yours, can you assure me it'll work? Not worried about it being perfectly accurate, just within a few hundred rpm across the rev range.

I'm not interested in anything other than the stock tacho, don't want extra gauges hanging around.

 

[Peewee]

not sure the jaycar unit can do it as i dont trust it

The Jaycar unit can only double or halve the incoming signal.

 

[sideshow]

yes thats y i dont use it
plus if it fails you then have to fix it under warranty which means installing the expensive ones i use

without car infront of me i wont garrantee much
i think its too much to risk as if it was only 50 bucks then it doesnt matter

first try this

hook the tacho wire from the 1uz to the tacho in the dash

take car for drive and see if tacho movesa tginy bit when u go past 3 or 4000 rough guess

if this works then u just need to multiply the signal

i personally would rip the cluster out and send it to get modded

half the price