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

[Disturbed1]

would that apply to cars runnign a soft limiter as well as a hard cut (both ignition)

[thechuckster]

soft cut is usually a timing retard so no need if your ECU supports a soft & hard rpm limit.

[Disturbed1]

think the ems soft cut rotationally drops A cylinder and the hard cut, cuts them all...

[thechuckster]

same sort of thing for MSextra tho i think you can determine how many spark events are dropped, plus you choose whether the hard cut is spark only or spark+fuel cut.

[The Real Roadrunner]

soft cut is usually a timing retard so no need if your ECU supports a soft & hard rpm limit.

im yet to see an ecu configured with a soft cut like that, most will intermitently drop out a cylinder or 2.

i would set it up to pull timing before the soft cut and have the hard cut set 500rpm afterwards.

cheers
linden

[Disturbed1]

lets say your drivign along in 4th gear at 1000 rpm and plant your foot

u instantly go from vacc to 0-3 psi between 1000 and 3000 rpm then u start climbing boost quickly (esp for me with big turbo)

is this a high load situation which i shoud be running very conservative timing values?? if so whats conservative

[Kyosho]

lets say your drivign along in 4th gear at 1000 rpm and plant your foot

u instantly go from vacc to 0-3 psi between 1000 and 3000 rpm then u start climbing boost quickly (esp for me with big turbo)

is this a high load situation which i shoud be running very conservative timing values?? if so whats conservative

These are the sorts of things I'd love to know!

Also, at cruise speeds, like around 3000RPM just cruising in top gear down the freeway, most people run 30 - 40 degrees of timing...
If running say locked at 15degrees, can this cause the exhaust to get excessively hot?

[1JZ-Rolla]

lets say your drivign along in 4th gear at 1000 rpm and plant your foot

Why would you? Are you driving a 16-wheeler with 2100rpm redline?


and yes, locked 15 degrees timing is not a good idea in any instance other than to check base timing. As you mentioned Kyosho, when on high vacuum/revs the exhaust gas temps will get very hot. Its far from ideal, and can eventually damage exhaust valves etc.

[JZA70 R]

lets say your drivign along in 4th gear at 1000 rpm and plant your foot

u instantly go from vacc to 0-3 psi between 1000 and 3000 rpm then u start climbing boost quickly (esp for me with big turbo)

is this a high load situation which i shoud be running very conservative timing values?? if so whats conservative

In my opinion, yes you will be placing load on the motor but you wont exactly be stressing it out to the point where you would specificly need to take careful consideration into the tuning.

For example, wot and 20psi @ 7000rpm will be high load and high stress on the motor. It will be very sensitive to timing and fuel and knock probability on u98 would be high.

wot and 3 psi @ 3000rpm the motor will be loaded but not stressed. It will not be super sensitive to timing or fuel and will be forgiving with tuning errors. These are the points of your map where you can experiment without too much worry.

These are the sorts of things I'd love to know!

Also, at cruise speeds, like around 3000RPM just cruising in top gear down the freeway, most people run 30 - 40 degrees of timing...
If running say locked at 15degrees, can this cause the exhaust to get excessively hot?

I think i understand your theory behind this thought, but its not neccessary. IIRC at 15' advance fuel will still be burning as it exits your exhaust valves... not sure if that would be the case when there is sfa fuel being used at cruise but you get the idea.

[big_zop]

wot and 3 psi @ 3000rpm the motor will be loaded but not stressed. It will not be super sensitive to timing or fuel and will be forgiving with tuning errors. These are the points of your map where you can experiment without too much worry.

While you say that fuel and timing values might not be critical in this point - i assume this is from a druability point of view. Could it still be considered critical to throttle/boost reponse even though the amount of damage caused but less than perfect numbers are not significant.

This is a great thread and although it will be a while before i can put any of it into practice, it has been a great source of information. Keep it up guys!

[1JZ-Rolla]

The only way you could be certain of the absolute correct timing for your particular setup at WOT, 0-3psi vacuum and relatively low revs would be to progressively increase timing from a conservative start (say 20-25 degrees), and tune for MTBT (Minimum Timing Best Torque) on a dyno...

Or progressively increase the timing in the same manner whilst using knock-ears or similar during a road tune.

Too little timing at this point will result in excessive exhaust gas temps, this is quite important as potentially your engine will spend a long time at ~2500-3000rpm and zero vac/minimal boost when climbing hills on the highway.

And yes, having your engine producing best torque at this point will also assist in lowering your boost threshold (not to be confused with turbo lag).

Cheers
Phil

[thechuckster]

im yet to see an ecu configured with a soft cut like that, most will intermitently drop out a cylinder or 2.

MSExtra will do this ... i'll try to find or generate some screenshots to show the tuning interface.


edit: the code I use (MSExtra Hires) drops the timing to a fixed angle for a user-set duration, then if that continues or the revs hit the hard limit, it drops sparks based on a total count and number of sparks to drop. You can set the kind of hard limit.

Attached pic is the interface as shown in Megatunix. These are not my numbers, just some stuff I put into the interface.


edit 2: i'll have a look at whether the newer code (uses the next generation ECU compared to mine) cuts the timing to an arbitrary advance angle or retards the timing based on where the engine is in the current ignition map.

[JZA70 R]

While you say that fuel and timing values might not be critical in this point - i assume this is from a druability point of view. Could it still be considered critical to throttle/boost reponse even though the amount of damage caused but less than perfect numbers are not significant.

This is a great thread and although it will be a while before i can put any of it into practice, it has been a great source of information. Keep it up guys!

yeah from a durability pov.

if your gonna be silly with numbers in this range then yeah you could adversely affect torque and throttle response.

[Disturbed1]

anyone runnign logworks or innovate datalogging know of a good way to overlay maps to see any changes??

the 'roads' that i been tuning on are not exaclt flat so i think the acceleration diff between goign up the hill and down the hill make it look like my tunign is making a huge imporvement on the accelleration ahha

[Disturbed1]

heres my latest ecu log

i have since made a few changes which was make the soft limiter at 6800 (was 6900). hard cut still remains at 7k. added a new load point between 6500 and 7000 and ramped up the timign another .5 degree at the 6500 load point then started cutting at 6750.

also made a few tweaks to the fuel map to try smooth out the afrs.

cant hear any noticeable knocking to the human ear over the gate but im hoping the values are pretty conservative. did about 15 runs tonight and motors still alive so cant be that bad