1jz-gte major power taper beyond 5000rpm

[urantia]

its stock as a rock, but it does sound most likely that the ecu is detecting knock and pulling timing. so i should just get a single bottle of octane booster and reset the ECU and see how that goes after a few runs.

I was getting a misfire on startup not long after i installed the 1jz but pulled the coils and plugs and gave them a going over and that stopped the misfire.

Strange tho there is a guy in hobart tas with a 1jz hilux making 250rwkw on stock Ecu (but a single turbo).

[urantia]

by the way thanx all for the advise. i will be sure to let you guys know how i go.

[Maverick]

Hey guys just some food for thought, perhaps the o2 sensor is rooted, my 1jz cressida ran richer than you`d believe, wouldn`t rev past 6k and struggled to get there plus it went like a dog, turns out a small cut from my mates angle grinder in the exhaust, (when he helped cut the motor out of the half cut - car was written off) near the 02 sensor caused havoc on the ecu, got the hole welded and power quadruplled. I`m currenty having a similar problem with my girls soarer- stock ecu, cat back 3` and front mount, car goes ok until about 5, then produces low power, and it runs super rich (very bad fuel economy)... any ideas while we`re on the subject? are the ecu`s prone to fucking up? note, car has had manual conversion, but uses auto ecu, however my cressida was the same and it wasn`t a problem

[JZA70 R]

mine stops making power at low 5000 rpm, are you sure its actually a problem and not a natural characteristic of a stock 1JZ?

[2JZR31]

My brothers soarer pulls hard all the way to the limiter.

[acmtt]

Definately a problem, i should pull hard to about 6500 and then still pull but not as hard to redline 7500 in a manual. I documented my old Soarer's mod path. Dyno graphs (http://www.thesoarer.com/Default.aspx?tabid=504 )

try bridging the fuel pump ecu as well. Diagnostics port Fp and B+ with a paperclip.

Just an easy one to rule out.

So with all the good suggestions above , i hope its sortd quickly.

[urantia]

mine stops making power at low 5000 rpm, are you sure its actually a problem and not a natural characteristic of a stock 1JZ?

Does your rpm needle get to 5000rpm then go slow as a snail to 7000rpm (3-5 seconds to get up there)

acmtt, thanx for the dyno graphs. I wish there were a dyno here in tas that i could get this properly diagnosed. Will try the octane booster ad ecu reset hopefully tommorow.

Might also try to get a video of the car accelerating so you guys can get a better guage of what might be the issue.

[acmtt]

My tacho needle moved quickly, my friend thought i just had a better engine than his...unitl he found a dodgy wire to a coil, that was only noticeable by the lack of revs up high.

Not saying thats definately what yours is suffering, but its worth a try.

[Hibba]

Something defently wrong, my 1JZ will pull all the way to the revlimiter with out slowing down at all.

[Buttocks]

My 1jz hesitates over 5000rpm when on full throttle, Its still got the stock ma61 fuel pump and i'm pressuming thats the problem. But it still has its power as theres no drop off like your talking about

[urantia]

I tried again, it all happens pretty quick and it's hard to keep an eye on the tacho the whole time, but the power goes flat beyond 5000, no increase or decrease just flat between 5000-7000rpm, i would of put it down to the power delivery of the 1jz, but the fact the needle moves so slow after it gets to 5000 is a worry. It really does move slow to get to 7000rpm.

I know with motorbike engines you can rev past peak power and the needle doesn't have this slow progression to redline like mine.

[Buttocks]

Can you tell us what your boost is doing at the time??

[urantia]

not accuratly no. But i will get a proper gauge for better measurement hopefully tommotow.

The stock boost guage goes to the max and stays there. And when i've let off the pedal it sounds like it';s letting off a fair bit of pressure. (what i mean is it sounds like the bov is working well)
but i guess that's next to useless without a proper boost guage.

The power delivery upto 5000rpm feels smooth. and consistent.
I might be able to fill up with some bp 98 octane for a test aswell. Left over from targa tasmania. (probably stale by now)

[joecoolmk2]

what car were you drivin? liam didn't tell me you had a car in it i watched all the cars from one of liam's mate's place at paloona.

it sounds like the timing advance is dropping off to me. or you could have a short somewhere in the ignition and not getting full power.

[urantia]

oh man don't talk about shorts! hehe i just spent the last hour in the dark and in heavy rain trying to get the postie to spark! it was shorting out somewhere else, just got it working but now the headlight is dim. *scrathes head*

but yeah it feels like the timing is getting pulled i have a feeling it really is knock sensor values in the ECU, as the fuel quality here in tas is so farken unpredictable, local servo petrol is sometimes good sometimes horrid (the owner said it was 100octane LOL), probably need to stick to BP premium after an ECU reset. (still to get some octane booster to really rule this out)

I'll come round see you sometime soon joe and hopefully get that 1uz cranking.