1JZ VVTi Novice adjustments. (Crackle and pops)

[BoyofBeef]

Hey Friends,

Total novice trying to educate myself a bit further on engine tuning, thanks for all of the posts from the regulars and link staff in advance. I already feel like I've learned a lot.

So to start my basic tuning, I thought I would see if I can create a "crackle and pop" map for on over-run starting with a lower limit of 3000 rpm.

My understanding so far on a "Standard" tune to make this happen:
Fuel-cut on over-run: OFF
Reduce ignition timing of areas of map with high vaccum. (From 36-40 to 14 as a start)
(Potentially add more fuel along the same areas of the map as ignition timing was reduced.)

Before:


After:

I am still you to drive on these settings, but I have gathered that I should follow the "snake" on the plot of the ignition table to validate that I am reaching 0 MAP on over-run, if not, adjust the table to accommodate.

Thanks for any/all advice, I know it's a bit of a pleb thing to want to tune in, but we all have to start somewhere, so please be gentle!

KR

- Beefy

[Vaughan]

I've kind of played with this in my MR2 but my setup is a little different. I have overrun fuel cut on with a 0.5s torque reduction of -40deg (max in overun fuel cut setting is 25 but I sneaked another 15 deg retard in using the 4D ignition table) and I find it does a combination of crackle pops and bangs when coming off the throttle into overrun fuel cut and reentry from overrun fuel cut back into throttle. From my experience with this my recommendation would be maybe go so far as 0deg ign timing when in overrun and you might need to add extra fuel (from memory turning wall wetting on which added extra fuel when coming out of overrun fuel cut add more pops and bangs).

You won't get anywhere near 0kpa MAP so probably best to just go take a log of a full throttle run then cut throttle completely and look at the log afterwards to see where it went. There is the risk that the overrun area will be very close to low throttle cruising and if this is the case then maybe look into leaving the main ignition table as is and having the 4D ignition table with a bunch of retard in it based on tps and rpm to make sure that the retard only comes in at no throttle rather than a similar vacuum but something more like 5% throttle.

Disclaimer: I'm not a professional tuner, I just play around with my own engines at my own risk.

[BoyofBeef]

7 hours ago, Vaughan said:

I've kind of played with this in my MR2 but my setup is a little different. I have overrun fuel cut on with a 0.5s torque reduction of -40deg (max in overun fuel cut setting is 25 but I sneaked another 15 deg retard in using the 4D ignition table) and I find it does a combination of crackle pops and bangs when coming off the throttle into overrun fuel cut and reentry from overrun fuel cut back into throttle. From my experience with this my recommendation would be maybe go so far as 0deg ign timing when in overrun and you might need to add extra fuel (from memory turning wall wetting on which added extra fuel when coming out of overrun fuel cut add more pops and bangs).

You won't get anywhere near 0kpa MAP so probably best to just go take a log of a full throttle run then cut throttle completely and look at the log afterwards to see where it went. There is the risk that the overrun area will be very close to low throttle cruising and if this is the case then maybe look into leaving the main ignition table as is and having the 4D ignition table with a bunch of retard in it based on tps and rpm to make sure that the retard only comes in at no throttle rather than a similar vacuum but something more like 5% throttle.

Disclaimer: I'm not a professional tuner, I just play around with my own engines at my own risk.

Hey Vaughan,

Thanks for the reply, really appreciate your input, I really am a novice, so any and all advice is a godsend.

I think I understand, so instead of the ignition table being "Active" from the MAP & RPM inputs alone, the 4D ignition allows the adjustment of targets if correct conditions are met. I.E. (For this table):

If MAP is 0, RPM is >=3000, TP = 0
IGN = 0

Does this not also allow that if my MAP is lets say: 100 kPa, and I let off the throttle after a hard pull (TP=0), that timing will be -15? across the entire table? (Essentially MAP is not considered in the 4D?)

Is there any way to allow for the 4D table to "Activate" only when MAP = 0?
Such as the scenario:
DI 1 = 1 (On) IF MAP (kPa) = 0

Thanks in advance.

 

[koracing]

You can always trigger the 4D map using a virtual aux output that you can use various conditions to control.  

 

As @Vaughan stated, it's highly unlikely you're going to actually see a perfect vacuum in your intake manifold (aka 0 MAP) so you may want to log some cruising and then sharply let off throttle and other coasting/engine braking scenarios to figure out exactly what MAP values you see in each situation.  It maybe that you will want to think about triggering based on TPS, overrun fuel cut % or some other factor to make this a little more seamless while driving.

[Vaughan]

I was thinking 4D ignition table always on.
I wouldn't actually have 0 MAP row in the main ignition table (or any other table for that matter) as I wouldn't expect you to ever really get below 30kpa.
I would leave all of the Main ignition table values as sensible ones and I would probably go with more like -30 than -15 in those cells in the 4d table (Based on what I think your MAP value would be in overrun that puts you at like 6 to 10 degrees btdc at 0% tps).

[BoyofBeef]

1 hour ago, koracing said:

You can always trigger the 4D map using a virtual aux output that you can use various conditions to control.  

 

As @Vaughan stated, it's highly unlikely you're going to actually see a perfect vacuum in your intake manifold (aka 0 MAP) so you may want to log some cruising and then sharply let off throttle and other coasting/engine braking scenarios to figure out exactly what MAP values you see in each situation.  It maybe that you will want to think about triggering based on TPS, overrun fuel cut % or some other factor to make this a little more seamless while driving.

Beautifully put, assuming I'm reading this correctly, the 4D will initiate when all conditions are met, these being:
MAP<10kPa (Or whatever value I see under no load)
DI Value 1 (DI value 1 normally being ignition (1=on, 0=off)

I'm a tad confused about the fuel cut value, I get less than/equal to 10%, but what is the % based on? As it appears to me that fuel cut is mostly a I/O setting? - Afraid the fuel cut table isn't giving me many clues - Apologies.

@Vaughan You were spot on about the MAP Values. Completely off-throttle I was seeing 20-40 kPa. Ended up tweaking to the values below with [fuel cut = OFF] Ended up with some decent pops when feathering throttle. A couple of times I got comical backfire with no feathering though until I started adding some throttle again, not a clue why.



Do you think the current timings I have in the table are alright, or too advanced?

Thanks again for all of your support guys. I'm learning a lot already.


 

[Vaughan]

Attach a copy of your tune please and I will show you what I was meaning

[BoyofBeef]

3 minutes ago, Vaughan said:

Attach a copy of your tune please and I will show you what I was meaning

 

JV Crackle 29.04.2021.pclr

[Vaughan]

Can't seem to open your basemap but the attached image is more what I was meaning. Are you cable or E-Throttle? if E-Throttle then make it APS based not TPS.

Ignore that the main ignition table values aren't the same as yours, they're just there to indicate that I haven't removed any timing from the main ign table.

 

Also you do still have overrun fuel cut off right?

[BoyofBeef]

10 hours ago, Vaughan said:

Can't seem to open your basemap but the attached image is more what I was meaning. Are you cable or E-Throttle? if E-Throttle then make it APS based not TPS.

Ignore that the main ignition table values aren't the same as yours, they're just there to indicate that I haven't removed any timing from the main ign table.

 

Also you do still have overrun fuel cut off right?

Hello mate, not sure why you can't open it, I've attached my latest iteration of the map (Along with the screenshot). For the previous runs I had fuel cut off, as I wanted to get a decent understanding, was popping fine with it off when I was running 13 BTDC

I've been trying to understand your paramaters and @koracing's a bit more. I'm wondering if I can exploit the activation delay time on the overrun fuel cut, meaning I can keep overrun fuel cut on, but have a few crackles just before it kicks in?

Please feel free to correct everything that is wrong in my assumptions.

Looking at the logs, there is a delay before fuel cut. (I've set to 2 sec, just to keep it at maximum value).
If I pull this in to a Virtual aux with the conditions that:
MAP < 30kPa
DI= On (Ignition)
Fuel cut % = <=10%

I'm a bit hung up on the fuel cut %, as I thought fuel cut was a "digital" output, On/Off, as that's what it states in the help manual?
Is the fuel cut % tied to the overrun fuel cut?

JV Crackle F-C ON 30.04.2021.pclr

[koracing]

I was simply showing there are multiple ways you could trigger the activation of that table using a virtual aux.  The fuel cut % being below some threshold would mean active when overrun cut is not active, since the G4+ doesn't directly allow overrrun cut status as a parameter that I could find.

[BoyofBeef]

1 hour ago, koracing said:

I was simply showing there are multiple ways you could trigger the activation of that table using a virtual aux.  The fuel cut % being below some threshold would mean active when overrun cut is not active, since the G4+ doesn't directly allow overrrun cut status as a parameter that I could find.

Shame about that really, could have a really nice setting if it was a parameter, and they extended the activation delay, rather than it being hard-locked at 2 seconds...

Could have a few lovely "Controlled" burbles before cutting fuel.

[BoyofBeef]

Okay, I think I've come up with a solution by exploiting the activation delay timer in the fuel-cut setting.

Bit of a mess, but here goes:

 

4D Has the parameters to reduce timing on over-run.
4D is turned on when VA1 Outputs "ON"

VA1 outputs when these conditions are TRUE:
MAP <40mPa
Timer 1 <= 2 (Activation delay for overrun fuel cut)

Timer 1 activates when VA2 outputs "ON" and has a max time of 3 (Timer will not go above this value when reached).

VA2 "ON" starts the timer when TPS<8% (Same as overrun fuel cut).

In theory, the 4D table should only be active for 2 seconds, and then shut-down. At the same time it shuts down, the overrun fuel cut table will take over, because the SW condition 2 would be greater than 2 seconds, the VA1 output is 0, therefore, turning 4D ignition "OFF"

This does require the timings to be synchronized, which should be with TPS%, but as for internal clocks and delays in processing, ECU may be out by a few ms?

Thoughts?
 

[BoyofBeef]

This is the driving time plot based on the settings above.
I am still getting backfire on partial-throttle above 2.5K, although it's not doing it when I depress the throttle for a while.
Although this plot is showing that fuel-cut is still enabled after the 2 second deadtime.

Having some issues with VA1, as VA1 should only be "ON" when: kPa <40 & VA2 <= 2(Seconds). It seems VA1 is only reading condition 1 from the table. So it's either a bug, or I have to fettle with it a bit and make sure everything is running as it should.

It feels like I'm 90% there though.

[BoyofBeef]

I know this is becoming a bit of a blogpost, but I've managed to get it to work flawlessly now.
This is just for anyone that is interested in getting a few pops and bangs on a gearchange/downshift without having fuel cut off all of the time, and, with some overlapping 4D and fuel cut ignition tables.

Disclaimer: I am not a tuner, simply a novice that is taking a bit of interest.

Above are my settings for this.
Cutting the long story even longer:
The fuel cut is on, but it takes 2 seconds to initiate because of the "activation delay" parameter.
Within these 2 seconds, we want the 4D Ign table to take over, but only for these 2 seconds, and then we want to return to "Normal over-run fuel cut timing" after these 2 seconds are over.
This is activated by Virtual aux 1.
Virtual aux 1 is "On" when: MAP > 40kPa & Timer 1 <= 2 Seconds & ECT > 70 Degrees C

We have Timer 1 on virtual aux 2 that activates when TPS%<8 (Same as fuel-cut)
We have Timer 1 set to 3 seconds (3 seconds is arbitrary, as long as it is >2 seconds, we are okay)

The 2 seconds on the timer are important, as we don't want any overlap (Although I'm not sure if it would make any difference when there is no fuel being injected). Once the timer is above 2 seconds, the "Pops and bangs" in the 4D table switch off, and the overrun fuel cut takes over.
It is also important to have the polarity for the timer as "Reset on Off/On edge", as we want the 4D to only activate when we take our foot off the throttle. The "Off/on edge" means that the timer resets when VA2 starts.

Below is the time plot for this, which should explain it better than I can on how this works. (Please note, pops and bangs 4D is called "Chav mode").


Shout out to @koracingand @VaughanI've learned a hell of a lot from this, so I appreciate all of your support.

Kind regards,

Beefy

[jdniss]

@BoyofBeef is there a reason you didn't use an MGP ignition table over a MAP based ignition table?

I found in my own testing, the engine would never drop as low as 0kpa on a MAP table, but would frequently drop to -80kpa MGP during decel/overrun,
which was still lower than cruise  at -70kpa MGP.

Similarly to Vaughn's config I had set 10° in those -80kpa cells during decel,
and overrun then pulls a further 15° out when it activates - rather than setting up a 4D ignition table.

[BoyofBeef]

On 5/5/2021 at 12:14 PM, jdniss said:

@BoyofBeef is there a reason you didn't use an MGP ignition table over a MAP based ignition table?

I found in my own testing, the engine would never drop as low as 0kpa on a MAP table, but would frequently drop to -80kpa MGP during decel/overrun,
which was still lower than cruise  at -70kpa MGP.

Similarly to Vaughn's config I had set 10° in those -80kpa cells during decel,
and overrun then pulls a further 15° out when it activates - rather than setting up a 4D ignition table.

Hey,

Only reason I used the MAP over an MGP is that my "standard" table to view is MAP/RPM. I expect you'd get the same result if you transposed it over to an MGP table.

The reason I have the 4D table is so that I don't have to modify the main table, and can have certain parameters to control what conditions I want to "Pop and bang". In my example above, they're pretty simple:
MAP < 40kPa
Coolant temp > 70 Deg C
Timer: < 2 sec (2 seconds until it cuts out)

You can change these values to whatever, or adjust them, so you could run it off of a switch linked to a digital input, for example.
Where if you were to run it on your main table, you would be running "10° in those -80kpa cells during decel" As well as the -15 adjustment from the fuel cut, leading to a total of -5°. Although it shouldn't matter, as at that point you've cut fuel anyway.

No right or wrong answers really, as the output is basically the same. I just like the flexibility and adjustability of running a 4D. Also, it's fun to experiment.

[koracing]

On 5/5/2021 at 4:14 AM, jdniss said:

@BoyofBeef is there a reason you didn't use an MGP ignition table over a MAP based ignition table?

I found in my own testing, the engine would never drop as low as 0kpa on a MAP table, but would frequently drop to -80kpa MGP during decel/overrun,
which was still lower than cruise  at -70kpa MGP.

Similarly to Vaughn's config I had set 10° in those -80kpa cells during decel,
and overrun then pulls a further 15° out when it activates - rather than setting up a 4D ignition table.

MGP vs. MAP is relative to BAP, so it's probably not as much of a difference using MAP vs. MGP if your staying at a relatively similar altitude.