Rb25det Power Fc Map/tune Discussion/development

[frozenwaffles]

hey guys!

ok so this thread is a thread for talking power fc tuning and all associated bits and peices. if you dont like what you see or read here then please save the criticism and go elsewhere...this is a positive thread only please!

its also for those who are completely technically minded, so some speculation is allowed as long as you have something to back the speculation up...lets keep it scientific too please.

ok so here are my two maps at the moment (if you want to comment on them please do):

most of my tuning is done on the road, with ocasional dyno tuning. this tune is 100% road tuned.

i will post more info about this tune as i have more time, but right now im at work.

my mods are:

RB25DET

Apexi Power FC with Boost Control Kit

Apexi Power Intake

Custom Intake Pipe (AFM to turbo)

Custom CAI (from front bar to pod)

Custom Pod Filter Enclosure

HKS Adj Ex Cam Gear (retard 4deg)

Nismo 555cc Injectors

HKS GTRS Turbo

HPI Low Mount Ex Manifold

Xforce 3"-3.5" turboback exhaust

Just Jap Bar and Plate FMIC

Tuning details:

CAS position is 15btdc with timing light sensor wrapped around the three wires just before they plug into coilpack on cylinder 1. the loop wire gives a false reading on my battery powered timing light.

injector settings in power fc are 66.6% correction and +0.18ms lag adjustment

[The Mafia]

don't want to burst your bubble, but comparing maps is useless because some people have their injectors dialed in differently, different lag times etc and also the CAS can be in a completely different spot and thus making the timing different.

I'm keen to see if any has made and good changes to the other parts of the FC though, or the other tabs in FC-Edit

[frozenwaffles]

no i aggree with you there.... but we can atleast say... 'i did this, and this happened'

its not about comparing maps but rather tuning techniques. this thread is about tuning and leraning how to tune. i have books and the way from america about advanced efi tuning. this is a personal project and i am interested in getting feedback from people that know more than me if they are interested in helping. i am just getting the ball rolling on here...

new info above...

[paulr33]

set the entire row of P01 to 0ign timing if you want your car to pop and fart its ass off on gear change or deaccel

[frozenwaffles]

yes yes we know that paul...lol

you must love a flatulant car yes?

[benl1981]

Thats a huge amount of timing in the low load cells..i.e in the 50 deg vicinity. I know Guilt toy mentioned not to go over 38 deg anywhere in the map due to increase in cyl temps. Was that BS or not.

I know mine could handle a lot more timing in the top left corner 10x10 but I havent as yet.

[frozenwaffles]

i know factory timing there is around the 43 deg mark there...i'll post up a map of the factory computer settings...

[frozenwaffles]

also just something i thought about, if you adjust the ex cam gear you alter the base timing by that amount too...so 4 deg retard would be taking 4 deg out of the base timing as well....

can anyome confirm?

[Dale FZ1]

If you pull off the CAS to adjust the cam gear, then good practice is to use your timing light and adjust your ignition to the same base timing. Otherwise yes, the whole timing map will be out by that amount.

Here's something about the two maps:

IGN. for full load tuning use Map Watch to follow the diagonal downwards ramp as the engine accelerates from say 1600rpm to 4800. Aim to make the progressive reduction in timing incremental (ie no huge steps). Watch your knock counts in those cells, and be aware of interpolation from adjoining cells. Interpolation is something to be aware of particularly for full load fuel settings as well. This can make it difficult to get a particular cell "nice" because of an artificial raise or drop in fuel or ignition for that cell because of the variance in its neighbour.

INJ. especially on very light trailing throttle decel as you go from load row 2 to row 1 where decel fuel cut occurs, it can be difficult to eliminate a slight throttle hunt that feels like it cycles on-off-on-off-on-off. If you get that feel, check the AFR log via a chart to verify. I have run row 2 very lean (around 15.5 AFR) and it was terrible. At around 13.5 the hunt is greatly reduced but still slightly noticeable. Trying to get any meaningful log of AFR on row 1 is virtually pointless due to decel fuel cut.

As per Mafia's comments, some of the other settings that can be adjusted are worth reviewing too.

[frozenwaffles]

i like what you have to say mr dale...

one point about the timing light and cas though...because the cas uses the cam for the 'turning' of the sensor...if you set the timing to that then the intake valves are opening at the wrong time. the timing i would imagine needs to be set to the intake cycle rather than the ex as the cas also tells the ecu/pfc when to fire the injectors...

so hence my question...if i have 4 deg retard of ex cam timing, the do i set the cas to 11deg base timing or 19deg...

[Dale FZ1]

The CAS uses the signal to determine the position of the CRANK, not the camshaft. It's just convenient to mount the sensor on the end of the cam. So reset your timing to 15 degrees.

Remember the timing event is described in relation to TDC - Top Dead Centre of the piston through its stroke. So it's all about the crank position.

Edited April 30, 2008 by Dale FZ1

[Dale FZ1]

set the entire row of P01 to 0ign timing if you want your car to pop and fart its ass off on gear change or deaccel

Other than because you can do it, why would you want your car to sound like it's poorly tuned?

Guilt toy mentioned not to go over 38 deg anywhere in the map due to increase in cyl temps. Was that BS or not.

I recall some comments from him about ignition timing, but suspect it was in relation to tuning for emissions. Less advance generally equates to higher exhaust temps. My understanding is that extra advance will result in more efficient running + torque, but past a certain point the emissions output is increased in a certain area. So there is a sweet point for tuning for either emissions or torque, but they are often different. Browsing Guilt Toy's thread about emissions sort of covered his findings.

Edited April 30, 2008 by Dale FZ1

[frozenwaffles]

yes yes i realise now. so if you make any adjustment to the ex cam gear, you need to reset/check the base timing. but it still always remains set at 15deg...

[Dale FZ1]

No, not necessarily. You set a base timing figure, arbitrarily 15 degrees. The amount you see in the electronic map is added to the base figure, to give TOTAL advance. It is total advance that counts.

The reason for checking your base timing is so you don't have to make wholesale changes to the IGN map to compensate for whatever amount it might otherwise vary from the arbitrary 15 degrees.

[RPMGTR]

No, not necessarily. You set a base timing figure, arbitrarily 15 degrees. The amount you see in the electronic map is added to the base figure, to give TOTAL advance. It is total advance that counts.

The reason for checking your base timing is so you don't have to make wholesale changes to the IGN map to compensate for whatever amount it might otherwise vary from the arbitrary 15 degrees.

The PFC on RB25 uses 15 degrees as the idle ignition timing (20 degrees on RB26).

The purpose of setting the 'base' timing is to ensure that the engine is getting the SAME timing as shown on the IGN map.

So with the engine at warm idle, check the H/C to confirm the PFC is giving the engine 15 degs.

Set the timing with a timing light (by moving the CAS) to the same 15 degs.

This ensures the engine receives the same timing as we tell it to on the IGN map.

We get heaps of supposedly 'tuned' cars come in with the base timing out by 2-10+ degrees.

You can usually tell by the big on-boost ignition numbers.

These engines dont need/like more than 40ish degs on cruise and are usually in the teens on boost.

If you are well into the twenties on boost, usually the base is retarded and the engine is getting less than what the map says.........

[wolverine]

hi RPMGTR

can you elaborate on tuning with regard to ign timing.

if the ign timing is in the teens on boost with your tunes is it possible some other workshops are balancing boost and fuel levels differently and therefore increasing timing to compensate? or is it always when base timing is set incorrectly?

[Guilt-Toy]

way too much timing on cruise !

but whatever floats your boat

[frozenwaffles]

out of intertest, why is there too much timing ? espcially if it not knocking? what do you recomend?

[Kinks]

If you go crazy with your ignition timing on cruise it might not ping due to cylinder pressure being relatively low, but you generally want the flame/pressure front to reach your piston when it is already on the way down. If your peak cylinder pressure is near TDC you are wasting fuel, because the force pushes straight down on the piston, rod and crank and doesn't produce any turning force. The engine is most efficient when peak cylinder pressure is reached when the piston is "half" way down the cylinder, this means the crank journal for that piston is horizontal and maximum leverage / torque is possible to turn the crank. (halfway isn't strictly true but conceptually you can see what I mean).

More advance might also increase your NOx emissions, I can't remember if timing or lean fuel mixture was the primary cause..

Disclaimer:Iamnotanenginetunerandtheabovecouldbecompleteanduttertrashbutlogicall

itmakessensetome.

[frozenwaffles]

hmmm all sounds great guys...keep the talk comming...