Nistune Forums

PL wrote:I refuse to tune any car with drilled out injectors!!

PL

This comment is free. I run DT redrilled 740cc injectors with E85 since 2006, they work fine if they have been balanced and checked b/w them.
You should, they work like a charm.
More than drilling, you can shave (the small disc on the head where the holes are drilled) some JECS sidefeed 270cc and they will flow a constant 550cc. I tested it, they work very well.
Shaved sidefeed 370cc flows 740cc after ...

OEM JECS sidefeed 270cc are $15-30 per unit in China ....

These tables are the nightmare of the tuner.
Changing injectors size and reporting the size factor to these don't work.
You need to tweak them by hand, with trial and error. I needed 2 winters to get them right.
My Z32 runs E85 and even if I doubled the size of the injectors (370cc==>740cc), I increased a lot the values in these tables (particularly when cranking) to start up in all conditions on ethanol blend (-20°C). Below 13°C, only the unleaded fuel contained in the E85 (about 27% in winter) is going to burn, the ethanol itself stays liquid through the exhaust
I've never drown my engine and the car starts immediately on the first key turn.

So, trial an error, summer will be different from winter, each season will have its tuning session for these tables
The best way is to have a wideband and purpose is to get about 10.5 AFR during few seconds after start up ("after start enrichment" table dictates this), then it should raise quickly above 12, and the cold/warm start enrichment tables make their job. I have a cold start table a bit richer than the warm start table thinking about fuel economy for warm start (>20°C in my case) and to have good drive-ability when starting from cold or in mid-season (15-20°C outside).

It would be interesting to find out which tables have to be altered if you just change the injectors and not
the fuel composition.

I was under the impression that just the FIRST TIME ENRICH table is in mS and the rest of the enrichment tables is in% based on K (the size of injector)

Then we have
After Start Enrich
Cold Enrich (Cold Crank)
Warm Enrich (Warm Crank)

Did you find out on what values these tables are based?
Also are they just fuel adders to the standard fuel map?

When does each of these tables 'kick in'?

As said I have issues while warm cranking, and have to operate the throttle to get the car going ..

Also judging from your screen shot you seem to have increased fuel, no decreased ?


Cheers!

I just changed the values back to original. Car starts much smoother. Increased colder values 0-20 richer than stock. Seemed better. Will have to play more.

Do you mean all values?
Or just the timing?

Just the crank enrich

There’re a lot of branches in the code, so getting the quintessence of these tables is not easy.
I did when I was on this topic but it was 2 years ago so I forgot since.

AS_ENRICH,&H7E00,16,1,16,1,After Start Enrich vs Temp
CRANK_ENRICH,&H7E20,16,1,16,1,First time Inj vs Temp
COLD_START_ENRICH,&H7F30,16,1,16,1,Cold start enrich vs Temp <= 15 degC
WARM_START_ENRICH,&H7EB0,16,1,16,1,Warm start enrich vs Temp => 15degC

In sequence, the ECU computes under interrupt:
I. AFR ratios (self-learn correction factors)
II. Air
III. TP
IV. Injection
V. Limiters
VI. Knock enrichment
VII. Injection output pulses

Less often, some additional enrichment is computed. 7E00 table is part of this additional enrichment, only applied if knock maps are used.
Remember the knock maps are used when engine is started up from cold and till the throttle is touched for the first time.

Basically, there’re 3 routines of injection computation depending on engine conditions.
1) A main routine of injection computation is called and based on TP. If conditions are met, the OEM lambda sensors correction values are also applied .
The output injection values are bank1 and bank2.
2) If knock maps are used, another injection routine is called and a basic injection is calculated without taking into account lambda sensors. Values got in 1) are overridden.
Remember the knock maps are used when engine is started up from cold and till the throttle is touched for the first time.
3) Then if temp initial is <10°C, cold injection routine is used and 7E20 table is used inside. There’s a warmup counter associated to this routine, so it’s only used during few seconds after startup and never called again after.
The ouput of this routine is, if the new calculated values are bigger than the bank1 and bank2 calculated in 1), bank1 and bank2 are updated accordingly

Regarding the tables 7F30 and 7EB0, they are correction factors related to AFR according to the current engine temp and so, they are used in I.
The choice b/w both is the engine initial temp (< or >15°C)

So, what’s the conclusion ?
The naming AFTER_START_ENRICH and CRANK_ENRICH is a bit misleading, b/c a lot of conditions are behind.
I can understand why 7E20 is called CRANK_ENRICH b/c it’s also used in the init routine when the ECU is powered up, just to calculate the initial injection rough values (that are normally calculated by VII.) before triggering the starter. TP is not used, only interpolation according to temp.
7E00 is additional enrichment to keep the engine running just after cranking it up. TP is not used, only interpolation according to temp.

I told you, adjusting these tables is trial and error, and you need a wideband to check AFRs.
Adjust 7E20 till the car starts from cold on the first key turn.
You need to get about 10.5-11 AFR for few seconds after starting the engine and then, it should rise very quickly to 12-13 AFR. Adjust 7E00 accordingly.
7F30 and 7EB0 are easier to adjust, if you car struggles when moving in first gear with engine cold, adjust the values in relation with your injector change (and again check AFR when driving). You need correct timing too.

Thanks for your writeup rom.

From what ive gathered, the rest of the enrichment tables shouldnt need much modifying if k constant has stayed roughly the same ( as in my case). The crank enrichment table is a injection time based table, and will however need tweaking. now in latest beta matt changed the table from ms to % on rb20 map.

In my case multiplying the values by the ratio of old to new (270/440), made starting more difficult than if i left it alone. I have ended up increasing the colder values and it seemed to get better. Will play around over the next few days and see if i can figure it out.

Yes, the same for me.

I doubled the size of my inj. (370==> 740cc) but because I run E85, I have been obliged to roughly multiply the values by 1.35 or 1.5 in these tables to start in all temp. conditions.
It's injector related in some way but also fuel type related.

I'm running 94 octane, chevron fuel, and still found it necessary to ignore the "Adjust crank tables" feature of injector resize. I figure i will be richening most of the map over stock, at least the colder values.

Remember the knock maps are used when engine is started up from cold and till the throttle is touched for the first time

This is interesting, the software now probes the knock flags (well in particular 0x0082 address for Z32) to determine if main or knock maps are selected). Will have to monitor next time on the bench - normally I have CAS spinning straight from startup

Name definitions were taken from the Japanese ROM worksheet for RB20 and official RB30 documentation for their warmup tables (my original Nistune definitions started from RB30 and worked its way through other vehicles as customers requested they be added)

For example the following were added. First line is Japanese to English translation and later line was reinterpreted from RB30 sheet

TKAS EGI increasing in quantity revision 1×16
100/64% After idle enrich vs temp revision

TWST When starting output pulse width 1×16
TWK:10 ℃ Ms First Time Injection vs Temp

TKTW EGI increasing in quantity factor 1×16
TWK:10 ℃ 100/64% After idle enrich vs temp factor (non-neutral)

TADVC After the starting timing revision table water temperature 1×16
TWK:10 ℃ Deg After start timing vs temp

I agree these can be improved. Initial address definitions came from this type of information and adding translation and tracing was the main goal of Nistune. However conditional tables are what cause the main confusion. Where the table tracing can be improved (ie only highlight table during the known conditions) then operations become clearer

What I found on the RB30 from the FT enrichment was it was only used for a period of about 4 seconds after start and that the table usage ramped down using an ECU internal timer. However that may change completely for Z32 since knock sensors are used and new tables were added

Thanks Matt,
So more to come I guess ..

As for my issue with problems during warm start:

I fixed this by making an educated guess based on logs I did.

Basically I reduced all values from 50C onwards by about an additional 2-3mS. (that's 50% down)
Also I adjusted the TTPMIN table to go as low as .6mS

Here's a screenshot:

The Red Line is the previously adjusted graph (as the result of the resize)

Did it help you?

What are the disadvantages to setting the ttpmin to 1 accross the board?

Lowering TTP min like this can assist in (temporarily) sorting tuning issues

It keeps an artificial floor on the minimum amount of injection that the ECU uses.

However pulling TTP min lower basically removes the floor of minimum injection and allows you to get your tune correct making sure you have the correct amount of injection latency and multiplier

Cranking table will not look at TTPmin, K etc since it just pulls the injection time form this table and puts that value to the injector drivers

Other after crank tables are use to compensate following the start signal being released and transition from crank to idle

Matt wrote:Lowering TTP min like this can assist in (temporarily) sorting tuning issues
Other after crank tables are use to compensate following the start signal being released and transition from crank to idle

Yes, that has been exactly the issue ..
The car would not start while cranking with throttle closed.

That's why I reduced the amount of fuel while cranking.

TTP MIN sorted out my idle.

The car still bogs down if you operate the throttle too much while warming up.
But that will be sorted by further investigation