Chris@AMS

iTrader: (9)

If the injectors shut off, I assure you, your revs wont hang

I'd like to see what is up with this so I can give a more concrete answer to my customers as to why this occurs. Its been quite some time since this thread has been started. I don't think the correct people, who know how to read the ECU code, are involved in trying to figure this out currently.

I wish I had a bit more time on my hands, I would love to start dissecting raw rom code!

gear head

iTrader: (3)

Mattjin may have found the decay tables.

Try this thread:
https://www.evolutionm.net/forums/sh...d.php?t=365109

MR Turco

iTrader: (16)

yeah but i think some of the disassemblers need to look deeper into those tables. In current form we can't really edit them.

dan l

iTrader: (3)

I think this makes wayyyyyy more sense than the load axis. Good job on the find.

dan l

iTrader: (3)

I mentioned this like a year ago. I know for a fact that its a fueling issue causing this. The reason being is that I can turn my ignition key off when throttle hanging and the revs drop like a rock. The car is staying fueled when it happens, you can watch it on the wideband. DSM's don't hang, and you can also watch the wideband, it shuts off as soon as you lift on the throttle to shift. More correctly, as soon as the idle switch is made on a DSM you can do whatever you want, keep it full throttle whatever, and those injectors are going to turn off.

More importantly is that the reason WHY they do this is also known. It is done to save the catalytic converter. When coasting down big hills if the injectors were to shut off the cat would cool off. When you start driving again the cat has to get hot again to be effective. The longer it stays cold while your are driving the less it can process the exhaust gasses and the more it clogs up. Thus throttle "hang" is the OEM's way to extend catalytic converter life.

mrfred

iTrader: (50)

I'm looking at this now, and its not RPM either. It seems to be an air density value. I need to look at it more.

lucky13evo

iTrader: (4)

god i wish someone could co,e up with a definitive answer. This problem really bothers me on my car.

lucky13evo

iTrader: (4)

At thunderhill this last monday my throttle hang really became an issue, especially when trying to engine break for a corner. Anybody out there with a definitive answer?.

Evo_Jay

iTrader: (17)

If you look in this thread for my post, I posted up settings that eliminated throttle hang for me and didnt mess up cold start.

Also, seeing how we're both in Nor Cal and both have IX, I think you should try my setting.

My settings are post #229. Your axis' may be different, dont worry, just change the table to look like mine.

acamus

Agreed, it seems to be a value that undergoes baro and coolant temperature compensation, and is available via MUT_75.

Mattjin

Why doesnt someone just play with the delay maps as gearhead said. I have an auto so it is useless for me, but the maps do control delay times. If the car is hanging then fuel must still be injected, so cut the fuel off sooner and it wont hang. My rom had four maps for this, for Neutral and for In Gear, and both again with A/C on. I was asking months ago for someone with the problem to report if it solves it.

It is most likely done to improve throttle response on a quick gearchange, but why they would do this on a road going vehicle is anyone's guess.

MR Turco

iTrader: (16)

I think people are just busy with other projects - knock control, boost stuff, ect. I am sure this will be addressed in due time.

mrfred

iTrader: (50)

Turns out that the idle stepper control programming is extremely complicated and pretty long. Its spread across at least 20 (probably about 30) subroutines. There are quite a few tables that seem to play some sort of role. It seems that much of the code is written to calculate variable that is on the unknown axis of the idle stepper table.

Mattjin

I dont believe you guys. You have a possible solution and dont want to attempt to use it! It may not end up being the solution, but geez its not that much effort to change a couple of numbers next time you are flashing your car.

It only uses the main table as a base. Along with it are a few condition tables and error tables and from that it stores condition offsets in memory to "learn" the correct idle. The learned values are applied over the whole base table. The fix is to force the ecu to apply the decel fuel cut so the engine shuts off sooner when you lift off, rather then delaying things too long (hanging the motor), and its not so much in idle control unless you can find an instance where it suddenly runs alot higher steps.

mrfred

iTrader: (50)

At least one guy has solved the problem by tweaking the base idle stepper table, so I agree its worth a try. I'm just interested in seeing how the stepper system works with the hope that we may be able to teach the car a few more new tricks that we didn't have before. Unfortunately, the stepper control system is surprisingly complicated, and I doubt I'll be able to come up with anything interesting other than perhaps be able to define the unknown units of the second axis of the base stepper table.