Start-up Fuel and ISCV Tables
 

I have seen an insane amount of people having trouble with their start-up settings so I figured I would share my findings and add a little visual aid so people understand how these settings all work together during startup.

First thing, I would like to point out how important it is to get your idle and BISS adjustments set at operating temperature first (180*F+ or 82*C+) before finally dialing-in your cold-start parameters. You can do this by monitoring your ISCV Demand Trims and adjusting your BISS until the trims settle as close to 0% as you can. You want to adjust your idle as close to the stock ISCV settings as possible. This ensures that you are utilizing the entire idle-control valves range from 0-100% open. This will be very helpful, especially for hot start issues for some people.

Second thing, the idle-control valve only offers 120 steps from my findings. You may see the ISCV Stepper table shows more than 120 steps in areas but its most likely to compensate for any ISCV trims that may be applied, to ensure it will open fully during start-up. It also may help get the RPM up faster after intial start-up just after the starter finishes turning over the engine.

To log the actual ISCV overall position in Evoscan, use the formula below:

Third thing, there are 3 areas that affect idle RPM. Fuel, Airflow and Ignition Timing. The more advanced your timing is in your idle areas, the more power the engine will make and the higher the RPM will naturally go (to a point). If you have 17* of timing advance at idle and can't figure out why you have trouble getting your idle to go any lower, try less timing advance. Same for timing advance being too low, especially below your target idle RPM. If its too low, the engine may stall easily. Look at a stock evo timing map in the 0-750rpm/50-70 load area. See a huge bump in timing? Thats to help the engine have enough power to catch itself during deceleration if the idle control cannot control the idle from dipping.

I will start with the fuel tables first.

https://www.evolutionm.net/forums/at...1&d=1359140365

Why we need enrichment in the first place
Fuel doesn't atomize as well when it is injected into a cold environment, nor does it mix well with the air. Because of this, it's harder to ignite the fuel when it hasn't mixed well.

There are 3 primary tables that control the majority of the fuel control during start-up. Before messing with these too much, you must first dial-in your injectors, MAF scaling adjustments and ensure your fuel trims are all in order, above 180*F coolant temps.


Injector IPW While Cranking Starter:
This is the parameter that squirts the first large burst of fuel to get the engine to initially start. This should only be in effect while the starter signal is being read by the ECU (pin #71 on evo 8's). It is not an adder, its the exact IPW that the injectors will fire. It also locks the ignition timing to 5* while this wire is engaged. If someone wants to track down the table that locks the timing at 5* during start-up, I'd really like to find that since adjusting timing while cranking can make start-ups faster with bigger cams, especially with a fair amount of valve overlap.
NOTE: This table generally doesn't need to be touched on properly scaled injectors on pump gas. If the car seems to need less fuel to start well, instead of messing with this table on pump gas, try lowering the MAF Scaling table at 19HZ.

IPW Enrichment vs. Coolant Temp #1 & #2:
This multiplies the normal High Octane Fuel Map IPW value to compensate for the colder combustion chamber temps (and probably lower cylinder pressures) and may not be able to completely ignite the fuel mixture so more fuel is added to ensure the desired amount of fuel actually ignites.

[High Octane Fuel Map IPW] x [IPW Enrichment vs Coolant Temp]

Post-Cranking IPW Enrichment Adder #1 & #2:
This is added to the the base IPW from the High Octane Fuel Map which is also multiplied by the IPW Enrichment vs Coolant Temp table.

[High Octane Fuel Map IPW] x [IPW Enrichment vs Coolant Temp] + [Post-Cranking Enrichment adder]

We add additional fuel for the first few seconds after the engine initially starts to help stabilize the engines combustion, then taper the additional fuel off slowly.

9417:

8859:
-Jamie
(aka Jack_of_Trades)

The airflow is controlled via the Idle-Control valve in almost the same manner as the fuel during start-up.

https://www.evolutionm.net/forums/at...1&d=1359146072

ISCV Demand While Cranking Starter
This works just like the fuel, it opens the idle control valve to almost the fully open position while cranking the starter. This allows the cylinders to ingest as much air as possible at first.

Initial ISCV Demand (AC off-Neutral)
This is the base ISCV demand that all trims and compensation tables start from. Some trims are adders, some are subtractors. Regardless, this is the primary table that everything works off of.

ISCV Post-Cranking Demand Adder
Just after the engine starts and the [ISCV Demand While Cranking the Starter] table disengages, the idle-control valve will drastically start closing to prevent the engine from revving too high. The engine is still stabilizing itself so the idle-control valve cannot just drop to the [ISCV Initial Demand] setting without suffocating the engine and stalling. This table adds more Demand just after the starter stops cranking to prevent this, while slowly tapering back down to the [Initial ISCV Demand] to give the engine time to stabilize.

9417:



8859:






So now that you understand the 2 sets of 3 primary tables that help with Start-ups I can tell the easiest way to decide which tables you need to adjust.

• If the car won't start at all, adjust the tables labeled #1 for fuel and ISCV.
  
• If the car starts but then runs really rough or dies within the first few seconds, adjust the #2 tables.
  
• If the car starts, runs for a few seconds really well then begins to run rough or stall, adjust the #3 tables.

-Jamie
(aka Jack_of_Trades)

Good info there, good stuff {thumbup}

Ive been experimenting a lot with these tables lately since my injector swap. I have a few questions that would help a lot of people

how would you recommend setting these tables for larger injectors?

does it make a difference on 93 vs e85? would it be (value)*(old injector scaling/new injector scaling) and *1.3 for e85?

should one average the calculations with each other for use with both 93 and e85? so *1.15 instead of *1.3?

thanks

There should be no difference with any size injector if they are properly scaled. The only parameter that really would need changing is the MINIMUM IPW on very large injectors. Maybe a little tweaking if fuel pressure is low enough to begin to affect atomization.

The main thing again is proper injector scaling for the E85 tune. However, having a separate set of [Post-Cranking IPW adder] tables would be most beneficial IMO.

The best way to adjust the E85 injector scaling is to first get the pump gas idle fuel trim as close to 0% as you can above 180*F and then switch to the E85 and adjust the injector scaling to be as close to 0% as you can. The car will run fairly well on pump gas even if its too rich during cold start, not so much with E85. So, you'd want to set the [Post-Cranking IPW Adder] settings to be ideal with E85 and I bet the pump gas tune would still start fairly well. You really need to get your pump gas start-up's absolutely perfect first before trying to get the E85 start-up's dialed-in well. Otherwise it can be a headache.

Its unfortunate because the [Post-Cranking IPW Adder] is just that, an adder. Which means on pump gas with a 2ms base pulsewidth and an adder of 1ms, its adding 50% more fuel. On E85 with a 2.7ms base pulsewidth, the same 1ms adder is only adding 37% more fuel. The exact opposite of what we'd prefer really.

-Jamie

awesome job clearing up all that info!!, any chance of getting the xml code on these tables for 88591715? I have almost none of these tables on my evo ix rom. looked around and not much info yet.. will keep digging up for the xml code.

I will see f I can post up the known tables for the 8859 rom tonight. I'm pretty sure we have found almost all of them for that rom already.

-Jamie

im all ears man!! waiting patiently.. once i fixed my rev hang and cooler weather creeped around.. now i get the bouncing AFR after start up and the car bounces up and down.. after a few min and almost warmed up its fine, so i need these tables to fix my issues!

you happen to have a cleaned up and up to date XML for 8859 that can be shared? i feel what i have has so much clutter, would be nice to rid of all the useless tables that arent worth touching and just keeping the important only.

Well that's easy enough to do yourself . Plus 99% of the iscv tables are listed in the iscv disassy thread particularly for 8859 ..

Seriously organizing your own XML is fun and let's you put things where you want ..

Cross ref addresses and delete the old ones if you like .

I'm runnin 8858 so I'm waiting for updates which is a tad slower .. But no biggie

I have added the 8859 address' to post #1 and Post#2.

-Jamie

Got anything for a IX?

I literally just posted up the stuff for the 8859 IX ROM just before you posted lol.

-Jamie

wrong info. deleted

also been wondering why this is like this for the longest, any idea why these tables are blank ?

https://dl.dropbox.com/u/89860621/initialstep.jpg

Which rom ID are you running?

-Jamie