timing problem with 1j

[53TUP]

Hey guys,

I have done a 1j conversion into my 180, now since day 1 it has always been a bit slow and i initially thought it was because of the standard turbos so i decided to get a big single. So i got a t60-1 bolted it all on and it was making 315rwhp at 17psi. At that time i was happy with it but my tuner was not happy with the result so i drove it around for a while and took it back cause it was running really slow went back on the dyno and it was making 250rwhp at 17psi haha. He blocked the tps and fixed a couple of things and went back to 315.

Anyway i left the car with him and he but the timing light on it and it appears that the car has been only running 8-10 degrees of timing this whole time.

now my question is does anyone have an idea of why the car is retarding the timing? we have changed knock sensors, changed computers. And still no change.

If anyone has an idea that would be great as this is robbing me of a fair amoutn of power and also i increasing combustion temps.

P.S. its a jza70 half cut, manual, manual computer.

[urantia]

I will be very curious to see what you find out, as i believe my 1jz had been doing the same.

[chris davey]

You made 315rwhp with 8 deg of timing? I don't think so. When you put the timing light on it did you give it a bit of a rev and see that the timing advanced. On mine I could clearly see that it went past the furthest mark which I think is 15deg.

As you are single turbo already, I would just save up a bit and get an aftermarket ecu. I am biased but I love my microtech

Your mechanic knows how to check the timing right with the coil on plug setup right?

I don't know about all these OBD scanners or whatever they are but if you want to monitor ignition timing accurately an aftermarket ecu is the way to go.

BTW my static timing is 8 deg on my 1j also but it definitely increases when I rev it.

[Vios-GT_07]

now that you mentioned it, are you sure it's 8 to 10 degrees even on revs??

diagnostics.. if it's not in limp mode then yea u'd be getting a fair bit of advance on it... from memory it does about 20 degrees or so halfway through the rev range , probably 3500 rpms or so? this was done with a diagnostic machine through the OBD (or was ot ODB) port...

[YelloRolla]

If anyone has an idea that would be great as this is robbing me of a fair amoutn of power and also i increasing combustion temps.

Exhaust temps may be higher, but combustion temps are likely to be lower (if indeed there is any temp difference).

Is the cam timing correct? My wife's 1JZ (VVTi) made 197kw (~260hp through the auto) on 12psi.

Which mathematically is the same as what you are making! 263(hp)/14.7 + 12 = 9.85hp/psi
Your power figure = 315/14.7+17 = 9.93hp/psi (although one would expect a bit more due to the larger charger).

So, I am not so sure that your power figure is too far away from what it ought to be

[sideshow]

timing is easy to check on the dyno
just scary checking it while someone runs the car up on the dyno
your tuner should be able to check this if he is an experienced tuner

we used to do this often on old datsun carby engiines to adjust maximum timing on the
L20s

another thing to do first is make sure top dead centre is accurate
mark the pulley properly

little things like this make it hard to see timing

and if you also use a retard timing light makes it easier to check timing

and alsong make sure your reading the pulley the right way

[53TUP]

spoke to him today he said on the dyno the most it was running on boost was 12degrees which is very ordinary.

i found a wiring diagram so he is going to go through some wiring to see waht he can find. this problem is very annoying and hind sight is 20-20 but i really can't afford to buy a computer at the moment.

any other ideas anyone?

[sideshow]

if its a conversion how good does the auto electrician know what he is doin

i have had this prob before and the ecu is in limp mode and stays at 10 degrees all the time this cause the egnine to miss at around 3 or 4 grand

so i dont know how yours gets so much power for that little timing

if i were you i would forget about the power figures and just see how the car dirves
maybe compare it to other 1js

cause if you had 12 degrees timing all the time my nans excel would probably keep up with you heheheheh

and when you say he blocked the tps what do u mean

he is probably tryin to bodgey up the problem by fart assing round with the other sensors rather than finding the problem

you should not have to fuk round with other sensors unless they are faulty and you should not have to fudge the readings of them either

[53TUP]

the guy who is tunning my car really knows what he is doing and he recons it is a fair bit down on power.

my mates soarer with same size turbo, manual pretty much exact same mods is making 370rwhp at 1.3 bar. i only just beat him as my car is lighter and he had an extra passenger.

when it had the standard turbos on it, i only just pulled away from a car with 200rwhp so it was really slugish even back with the twins on there.

[sideshow]

when you say tuning
what is he doin

do u have std ecu
or piggyback or what

if its std the only tuning u can do is change the plugs

[53TUP]

i got an safc and fuel reg.... the tune at the moment is spot on its just it isn't making what it should... he has tuned alot of 1j's and he recons it should be atleast 350rwhp, he recons there is something wrong with the wiring on the car causing the computer to retard the timing.

[sideshow]

it could be the wiring causing it to do that

i have seen it before

its not really retarding timing

its stuck in limp mode and not advancing the timing

drive the car to sydney and i can fix it for you

[53TUP]

yeah that sounds right about it just not advancing the timing... cause even just after 1 run on the dyno the manifold is glowing red...

any idea where abouts in the wiring that could be causing it to go into limp mode?

[chris davey]

So have you done diagnostics? If not, do that first.

Also, what size injectors are you using? What % correction are you using on the SAFC? If you have to use a lot of -ve % then it also advances the timing, if it advances too much and sees knock then it will reduce it to save the engine. So I would reset the ecu after you have done diagnostics and try again.

[53TUP]

can't find a scan tool for a 70 series supra... and i don't know if the guy who wired up the car even wired the diagnostics plug up correctly.