1jz-gte major power taper beyond 5000rpm

[Mr Ed]

Im betting you have the old fuel pump still, my money is on low fuel pressure at high RPM hense knock sensors retard everything, hense no power.

If you have already done so, a fuel pump upgrade could definately help.

[wiso]

he has already done a fuel pump upgrade, that fixed alot of problems after he first did the swap

[urantia]

sadly i think you are going to have to take it to someone who knows what they are doing

lol that was a loaded comment yes i took it the wrong way lol.
Look i'm using the process of elimination ok lol. I don't know anyone that would match the knowledge of you lot on these forums here in tas.

If only there was a dyno around here! -

But yes boost is stable, and no smoke out the back at all very clean burning all the time. (no rich smoke gear changes or turbo seals leaking etc)

It's not a major major power loss i can still hit it in 2nd and have the car screaming up the street sideways. The power is not there like i first had it running tho. One thing i should mention is i may of cooked the poor motor when i cained it with a blocked radiator. (yep always have your halfcut radiator cleaned/checked before driving.

But my compression is good within a few PSI from eachother.


Tell me whats 3rd gear like for you guys? when i floor it in 3rd i can get to about 5000rpm where it pretty well stops going anyfurther, perhaps really really slowly! i certainly can't seem to rev 3rd gear out and of course 4th and 5th would be even worse.

Computer gives me no error codes but i have it wired correctly becuase i was getting codes for a few wires i left off such as the speed sensor.

[SL666]

i was indeed meaning, take it to a workshop that knows their shizzle, (if you can get to one)

get around to checking the timing yet?

[urantia]

A few more things i need to confirm are things like my clutch isn't slipping, i know my throwout bearing is starting to make a noise.

Breaks aren't dragging or my handbrake is adjusted right. (spose that's scrapping the bottom of the barrel but i'm running out of things to test.

[urantia]

Yep took front timing cover off lined up TDC and those camgears are spot on. Might have to try another ECU too.

[Mr Ed]

Have you checked for error codes?? Sound like something is putting it into safe mode.

[urantia]

yep i certainly have.

The power loss wasn't a sudden change it was gradual as far as i can remember.

(yep my CEL is wired up and it does work, codes will come up when there genuinly is a code there.)

Whats 3rd gear like in a stock manual 1jz supra? easily wind out beyond 5000rpm? becuase mine gets to 5000 and pretty pegged there with no more to go. (or just extremly slow to rise above 5000rpm)

[Endless]

Try another ECU before anything else, heard numerous stories about them doing strange things like this and have also experienced this first hand, i'm 90% this is due to the capacitors leaking and their age as i've had my old one apart and they are all toast.

[urantia]

Yeah i reckon thats a good idea/. Capacitors only have a lifespan of about 20 years and thats considered pretty good.

I did try to open up my ECU before i installed it to see the caps, but the thing was almost welded shut i think it had been opened up before by the looks of the marks on the screw heads.

[urantia]

just an update, whent and buaght a decent K&N filter and some better rubber hose from a wrecker, had a good elbow shape which i was after.

reset ECU whent for a drive, seemed abit better, almost say that solved it. Ended up having a drag with a jza80 musta been NA 2jz-ge becuase i left him for dust. Didn't want to race a fellow toyota but he started it.

Still seems to have issues revving from 5000rpm and up. I msut be going crazy and thats how it is supposed to be. I must just of gotten uesd to the power. Really doensn't feel like a 280HP motor tho. (minus %30 for drivetrain loss to the wheels).

Also have managed to find a 4wd dyno not to far from me! i never knew it existed! so i'll get it onto that dyno if possible and put my power paranoia to rest.

[EldarO]

why do you need a 4wd dyno?

and it sounds like your engine is being put into safe mode at 5000rpm, but the error code is only ever present during that time

as such, the error codes wont show squat unless the car is at 5000rpm, and most probabl under load.

does it do it in first?

if it doesnt, then its load related, as theres less load on the engine in first.

Eldar.O.

[urantia]

why do you need a 4wd dyno?

and it sounds like your engine is being put into safe mode at 5000rpm, but the error code is only ever present during that time

as such, the error codes wont show squat unless the car is at 5000rpm, and most probabl under load.

does it do it in first?

if it doesnt, then its load related, as theres less load on the engine in first.

Eldar.O.

I need the 4wd dyno becuase my supra has been converted to AWD you see.

i really can't believe that the engine is being put into safe mode at 5000rpm, but the error code is only ever present during that time
can possibly be true.

but you bring up a good point about under load, it would seem to be an issue when under load, pretty sure 1st gear has no issues revving right out. Will have to just check that tommorow. But yes a dyno will confirm everything.

Ah sorry the 4wd dyno thing is becuase it's the only dyno i know of within 300km radius from my place. (tasmania)