NO rev limiter on 1jz after conversion but wanted

[naten]

Hey guys,

Slowly ticking things off my list of things to do on the car and i stumbled over one i had forgotten about.

Basically car is a ma61 with 1jzgte (jzz30 auto ecu) and there is no rev limiter. Ive taken it off the end of the tacho (by accident and only briefly) and no cut was felt. Boost cut still works fine hower. Due to this fact i would love to get the stock cut working again.

Does anyone know what would cause the limiter to stop working? Ive done a heap of research and noone seems to know what makes the rev cut work they just buy a brand name kit that does rev cut, fuel cut and speed cut.

Any info is appreciated
Nathan

[PlacentaJuan]

maybe the guage isnt getting the corerct signal,

or the guage was designed for an engine with a different rev limit...?

[naten]

off the end of the ma61 dash is 8000 rpm
stock rev cut is around 7200rpm from what ive read.

unless the tacho converter i made is making the dash read wrong.....

[rob]

anyone else have a suggestion on this?

[Smokey228]

Im pretty sure the rev cut isnt related to your rev gauge... as i have my stock ra23 gauge hooked up, the the neddle creeps well past 8k and then stops for the last 2 k... I still have a rev cut...

Also, i beleive the redline is 7500rpm and rev cut is 8000-8200rpm...

Cheers,
jase

EDIT: Also, you could just hammer it through 3rd and wait for the rev cut... You should physically feel the power curve begin to come down as it nears to the rev cut... Atleast thats how i know when to change... The car starts to loose power at about what would be 7700rpm... and i shift at around what is probably 7900rpm...

[CrUZida]

Rev cut is an internal function of the ecu. Nothing external can affect it (assuming the motor is running right).

Either the rev cut is higher than the dash reads, or the dash isn't reading correctly at those levels (both equally plausible).

You may also have a modified ECU that has a higher rev cut (blitz, mines, harry lemon, etc)

[rob]

Rev cut is an internal function of the ecu. Nothing external can affect it (assuming the motor is running right).

Either the rev cut is higher than the dash reads, or the dash isn't reading correctly at those levels (both equally plausible).

You may also have a modified ECU that has a higher rev cut (blitz, mines, harry lemon, etc)

its a stock ecu, its been opened a bunch of times and nothing has struck us as non factory. We are of the same thought as you and thinking its the dash.

anyone in NSW willing to offer their tacho as a comparison test??

[fatboy13]

Jase is that on your tacho? cos stock revcut/limit is 7200 afaik, ive never gone anywhere near as high as your suggesting... especially when im making peak power at 6200...

Ill see if I can dig up my old tacho i had

[jeffro ra28]

borrow a hand held digital tacho or dial back timing light.

[Smokey228]

Hrmm... Bens probably right. I thought i read somewehre that redline is 7500 on a 1JZ and rev cut is 8000k or similar...
Maybe that was for someones built motor...

We'll my rev gauge reads somewhere around 11k when my engine hits the limiter...

Cheers,
Jase

[naten]

thanks for the replies guys

as rob said its a stock ecu blah blah

as per what cruzida (this is exactly what info i needed) said if the rev cut is an internal ecu function then the dash must not be reading correctly.

Which is worrying as i built a tach adapter from instructions from these forums so maybe they dont do an accurate job of converting the signal over.

Ill try and track down a tacho to test with and let u guys know what i find

cheers

[naten]

oh btw it is impossible to buy a tacho to suit 1jz/2jz etc out of the box

all listed tachos i have seen require an adapter which is gayzor

FYI autobarn sell the tach adapters for $177!!!! Might grab 10 and resell them they are such a good price


If anyone has a tacho i can borrow (or purchase cheaply) that lives in sydney somewhere contact me.

[CrUZida]

All aftermarket tacho's will work with the stock JZ signal, its only factory tacho's that need a booster.

I wouldn't be surprised if the tacho adaptor/stock tacho was accurate to say 5000rpm, and then pretty average after that.

Also remember that if its 5% out at 1000rpm (ie, reading 1000rpm but its really 950rpm), then at 8000rpm its still 5% out (reading 8000rpm but actually only 7600rpm)
You don't notice these anomolies at low rpm's.

[naten]

ah i see what you mean cuz the idle seems close ish but it could make a big difference at the other end

Wont bother borrowing a tach in that case will just buy one from supershit and return it when im done

thanks for your help mate will check it out with a proper tacho and see what i come up with +rep

[Mos]

Old tachos truly suck. I don't know how much I'd trust even aftermarket tachos. You could use a digital ocilloscope and watch the frequency. There is something called slew rate - and that's how fast something responds to a change in input. Let me assure you that your tacho needle will not keep up with the acceleration of the engine and the car. If you slowly accelerate up to the rev limit you might observe a more accurate number - try that first.

In the big scheme of things, it doesn't really matter, the ECU will cut it when it feels appropriate, regardless of what your instruments are showing and what you think you're observing.

Do all MA61s have digital tachos?

Mos.