The Tuning Talk Thread - Forced Induction EFI & JZ Tuning.

[rpsil13]

rpsil13: remove the coil pack in question off the head, ensure it has a decent earth, then use a short length of (good) plug lead to go from outlet(s) to the spark plug(s). Put timing light sensor on that short length of lead and see if it's getting triggered/sparking.


edit: do the same if you want to check base timing for the ECU (e.g. set spark angle to fixed amount, do above to #1, check timing light against crank and adjust ECU trigger angle on ECU so fixed amount matches what is showing on the crank).

so i checked the timing and it read 6 degrees btdc, how do i input that into the microtech ecu? on screen 31 all it lets me do is lock the timing to check it, but how do i adjust it?

[1JZ-Rolla]

You're testing my memory now, and I don't have my car here to check the setup screens, but I think the parameter you need to adjust is called "STATIC" under the options screen. Set this value to 6 degrees, then lock your timing and recheck to see if it now shows the locked value of 10 degrees at the crank pulley.

See how you go.........

[Indelible]

just curious how lean can the afr's be on a cruising highway type situation in vacuum not on boost

[pandaah]

correct me if im wrong but doesnt the cruising afr's lean right out to around the 15 to 16 mark?

[RONA]

14.7 generally, though some go a little leaner.

[thechuckster]

I wouldn't want to go any further than 16 for cruise.


edit: 14.7:1 will give you the best emissions result tho for economy you would then lean out and add a bit more advance. However, the higher your cruise speeds are, I'd make the AFRs closer to stoich so when/if you have to rapidly accelerate your not trying to swing AFRs from significantly lean to significantly rich in a very short space of time.

[Indelible]

yea i spoke to my tuner as i added a wideband gauge lately and getting 16.0 on cruise only between 2-3k on 10in hg vac above that it richens up to 14.0 ish and if i accel any harder it richens up straigh away so no problems was just curious
on 20in hg vac its around 14.5 afr and aproaching 0 it richens up also
get decent ecconomy too 530km to 58l and still make 311kw when i put the boot in

tuner said he can tune it out but it wont hurt anythin coz its in vacuum

[JZA70 R]

exactly.

my logic was, nothing bad can happen so why not lean it out as far as it will go to maximise fuel economy. I quite literally kept leaning it out until it started to buck, then added a bit more in to make it drivable. I think my cruise ended up being 16.0:1

good times.

[midnight_purple_GA70]

so now... cam gears and tuning them and degrees etc people have found to be useful?

car is 1jzgte
ebay t04z copy
17psi
microtech lt12s
IC
exhaust

it is to my belief that in my particular setup (large turbo with boost coming on about 4500rpm) that i would benifit from advancing the exhaust cam and retarding the intake cam to try to aid bringing boost on earlier?

i can understand this would limit the top end a bit but not sure by how much...
also i am currently revving it to 7500... would i be expecting a certain amount of rpm to lower this per degree of advance/retard?

will this significantly effect afrs?

then the other factor is same questions but with regard to a stock twin 1j...
microtech lt16
IC
exhaust
17psi

[1JZ-Rolla]

There's different schools of thought on cam timing in relation to response vs peak power, at the end of the day, for a given setup, only the dyno can tell you the real world difference. I know that's not what you want to hear though You can expect however that small changes to the exhaust cam timing are likely to have a bigger effect than the same amount of change on the intake.

Remember that when changing the intake cam timing, you are also changing the reference between the cam index and cam angle sensor........ just recheck that there's no effect on your ignition timing as a result. "Shouldn't" be a problem though as the actual engine position is still determined by the separate crank angle sensor behind the crank pulley. Just that in the Microleb software, you can't reprogram/calibrate the changing position of the cam angle sensor to compensate.


I'd say if you are running your 1JZ out to 7500rpm, then 4500rpm as your full boost threshold ain't too bad

[midnight_purple_GA70]

yeah fair points...

and its not a terrible point where its making boost but ide like it sooner i guess...

[1JZ-Rolla]

Get a better matched turbo, or a 2J bottom end

[midnight_purple_GA70]

yeah end plan will be a genuine garrett T04z with .86 rear which should see a bit of an improvement (hopefully enough of an improvement)

also 2jz bottom end is also on the cards which will change the above decision to a .96

[1JZ-Rolla]

What's your power target mate? I'm sure there are better turbos that will give you a lower boost threshold without sacrificing much if any power in the top-end on a 1JZ

Cheers
Phil

[midnight_purple_GA70]

long term i want it to be stupid... well maybe not stupid but in a ballpark of 600rwhp

wifes supra has a 35r on a 2jz for lightning quick lightswitch response...

as far as turbos go ill probably stick to the garrett range due to its long time proven track record...

the precision and such look like a good bit of gear but for some reason i think i want to stick with a trusty old garret for futur mod path...