sc400 Rev cut a 3750 RPM HELP URGENT

**Buttocks** · 12-10-2006, 05:47 PM

Heres the problem
I own a sc400 1991 model imported for Japan to Australia
When i picked it up it was hitting a rev limiter at 3750
Now the car is absolutely stock
i've taken it to the local toyota dealer who have fault check the car with the australia 1uz diagnostic tool (only shows about half of what it should as nobody here has a proper *** one) they found nothing
We have changed over these parts
ECU
Fuel Computer
igniters
AFM

Its a real horrible problem that no-one here can answer and its driving me mad, its 100 percent like the rev limited that should be around 7000rpm
i've been told to check the fuel pump now, but if the fuel pump wasn't supplying enough pressure it would hestitate but the car drives perfect except for the rev cut.
I also found today if i get to 90 kph and knock it back into 2nd it will go above 4000 but cuts out until the revs go below 3750 again and off it goes as normal, but a fault code comes up in Japanese which i translated to engine electrical system (kind of a broad statement)
Any help would be life saving

I"VE ALSO HAD A THOUGHT< WOULD A FCD (fuel cut defencer) stop the rev cut from coming in????

**jezza323** · 12-10-2006, 06:38 PM

no an FCD wont stop rev cut, FCD stops a boost cut in a boosted engine

**Buttocks** · 12-10-2006, 06:43 PM

FCD Fuel cut defencer . not boost cut defencer
Stops the fuel cut off that is hit when over boosting
It doesn't get controlled by boost, in the wiring diagram it is basically only hooked into the AFM wirings in the computer

**c2888** · 12-10-2006, 07:30 PM

Can you pin it and get codes the old fashioned way, via the the check light?

Dan

**Buttocks** · 12-10-2006, 07:33 PM

We have had the diag tool on it 2 times and both different tools, and it came up with nothing. Doesn't help that our australian diag tools are different and don't show have the stuff. So no error codes have come up at all. It almost seems like someone as asked lexus in Japan to put the rev cut down to 3800rpm, like a valet mode or something you would do to your kids

**thechuckster** · 12-10-2006, 08:40 PM

dumb question - are you sure the ignition system is wired up correctly?

given that you've replaced the ECU, it would suggest wiring is up the shit somewhere or an engine speed sensor is not happy.

perhaps look at the cam position sensor(s) and the 24 tooth wheel (it will either be in one of the dizzis or on the front of the crank.

if it was in valet mode you;d think the dash would have an icon displaying this?

Tried resetting/disabling the security system ?

**c2888** · 12-10-2006, 08:46 PM

http://us.lexusownersclub.com/forums...e=post&id=4720

how to pull codes with a short piece of wire
you don't need a scan tool

Dan

**Buttocks** · 12-10-2006, 08:50 PM

That would work if the engine light came on, but by what all the mechanics has been saying there is not fault in the system, it doesn't show a thing

**c2888** · 12-10-2006, 08:54 PM

You have to put the car into diagnostics mode
the engine check light WILL flash

steady flashing, means everything is ok, and you are on your own

OR

it will blink and pause, count the blinks between the pauses and that is the error the ecu has logged, read the page thouroghly and it will make sense

Dan

**Buttocks** · 12-10-2006, 08:57 PM

Will try it out tomorrow

**sideshow** · 12-10-2006, 09:14 PM

i have come across this on 1js and 1uzs but this had a rev cut at 2500 rpm

not sure if its a similar problem

but i will be in qld from nov 8th till nov 20th i can look at it for a fee if u want or if u can wait that long

**cambelt** · 12-10-2006, 09:20 PM

does it have that abs unit for the brake booster , if the pressure switch on it goes faulty doesnt it cause a rev limit . i can recall someone saying something about this on the soarer forum
Dave

**ace** · 13-10-2006, 12:16 AM

Wasn't there another thread on this same topic? do a search...
They were saying the ecu's in limp mode etc....although that doesnt make sense if you've changed the ecu.