How long for stock ECU to reach IAM 1.0?

[VTEC]

I recently just did a repair to seal a leak in the intake that was causing a lean code and dropping the IAM. The lean code is gone and I've been monitoring the IAM on my OFT to make sure everything is completely back to normal. On a Stage 1 93 octane tune running 94 octane fuel I can get the IAM to stay at 1.0 for a good half hour drive that includes full throttle pulls to the redline.

On stock tune, the ECU resets the IAM to 0.7 on startup which I've searched here is normal. It does gradually go up to .82 after a few blocks then .94 and after more than half an hour it did eventually hit 1.0.

My question is, does anyone know if it's normal for the ECU to take half an hour or more for the IAM to reach the full 1.0? Or is it slower if you recently just flashed it back to stock? It just sounds kinda dumb that the ECU is programmed to withhold maximum power for such a long time. Or maybe I am still leaking a small amount of air?

[wparsons]

It's not time based, it has to meet certain conditions before it'll raise the IAM. IIRC a steady sweep from 2500-6000rpm above half throttle will raise it. Do that a few times and it should be at 1.

[VTEC]

Thanks. I've been trying that Vishnu reset between 2000 and 6000 RPM. Sometimes full throttle, light throttle, half throttle. It's still kinda slow to raise the IAM. And obviously I need to make sure I have enough space to do it safely.

I actually found it was faster to put it in 6th and give it half throttle at low rpms. And easier since I don't need much space to accelerate.

I still think it's kinda dumb since nobody would purposely lug their engine like that.

[Tectoniic]

Bit of a shot in the dark but maybe the stock tune starts it at .7 so people are less likely to have knock/oil starvation before the oil/fluids are up to operating temps?

I guess you could test by cold starting the car and seeing if IAM gets up to 1 by the time oil is at least 180*F without driving it at all

[steve99]

Originally Posted by VTEC

Thanks. I've been trying that Vishnu reset between 2000 and 6000 RPM. Sometimes full throttle, light throttle, half throttle. It's still kinda slow to raise the IAM. And obviously I need to make sure I have enough space to do it safely.

I actually found it was faster to put it in 6th and give it half throttle at low rpms. And easier since I don't need much space to accelerate.

I still think it's kinda dumb since nobody would purposely lug their engine like that.

you also need to have little or no knock occurring or it does not work.


The stock tune knocks quite a lot in 2000-4000 area depending on fuel so it will sometimes be difficult to get iam to return to one, you need to be almost knock free.


The Vishnu trick relies on you running the engine through the rpm range at light throttle and low load, this should be the conditions for low or little knock so the ecu will detect this and return iam to one.


however if you still get knock in an rpm load range iam will stay below 1, until your pretty well knock free or very limited knock.


Aftermarket tunes are usually heaps better knock wise than stock tune hence the iam is solid at one.


log the flkc and fbkc knock parameters, if your seeing consistent knock iam will never get to 1

[steve99]

Originally Posted by Tectoniic

Bit of a shot in the dark but maybe the stock tune starts it at .7 so people are less likely to have knock/oil starvation before the oil/fluids are up to operating temps?

I guess you could test by cold starting the car and seeing if IAM gets up to 1 by the time oil is at least 180*F without driving it at all

stock is set to 0.7 to cope with crap fuel in some contries like south Africa where only 95 ron (less than 91 usa fuel is available). Same tune in all countries.


If your fuel is good iam will quickly climb to 1, if its not it will stay below 1 or even move lower than 0.7 to limit knock and protect engine.




Tuners generally set iam to 1 as they tune for a specific fuel and also the y don't want to have to mess around waiting for iam to climb to 1 before they do dyno runs after each flash. It will still decrement on knock.


the iam setting is just the initial value after flashing or reset of ecu. Then ecu learns a suitable value for iam based on knock it sees, this is then remembered and adjusted until the ecu is reset/reflashed. ie once the iam learned value will then be used for subsequent startups, its only reset to initial value on reset/reflash

[Tectoniic]

Originally Posted by steve99

snip

Everytime I think I have a decent idea/guess steve just has to come in and kill it with his knowledge

Thanks again!

[steve99]

Originally Posted by Tectoniic

Everytime I think I have a decent idea/guess steve just has to come in and kill it with his knowledge

Thanks again!

ha ha :-)


when ever you get concerned about a bit of knock take a look at this log from a stock car, stock tune in South Africa on the best fuel they can get 95 RON (about 91 usa) and these guys track cars on this fuel


IAM 0.2
still getting -2 -3 degrees FLKC


http://www.datazap.me/u/steve99/sout...2-20-28&solo=2

[Kodename47]

Originally Posted by Tectoniic

I guess you could test by cold starting the car and seeing if IAM gets up to 1 by the time oil is at least 180*F without driving it at all

Won't work. There are RPM and load parameters that have to be met, hence having to load the engine up.

[nikitopo]

Originally Posted by steve99

Tuners generally set iam to 1 as they tune for a specific fuel and also the y don't want to have to mess around waiting for iam to climb to 1 before they do dyno runs after each flash. It will still decrement on knock.

Yes this is true. Stock tune starts with .7, but tuners like to set it to 1. Main issue I can see is when you want to install a new peripheral and the instructions say to reset the ECU (e.g. disconnect/reconnect battery) . It makes sense to start with an IAM .7 setting and let the car gradually learn the new peripheral, than rushing things ...

[VTEC]

Thanks everyone. IAM rose really fast this morning. As soon as I got on the main road I gave it gas at low revs and it shot up to 1.0 before the engine even warmed up. Leaving work was another story. Was stuck in traffic for quite a bit and it wouldn't budge at all from 0.7. Even if I gave it gas in 1st and 2nd gear at low revs. Probably because it accelerates out of the low RPM range too quickly. But once the traffic cleared up and I could use low RPM in 5th and 6th gear the IAM shot up to 1.0 quickly again.

In both cases once the IAM reached 1.0, it never fell back down even under full throttle and high RPMs.

I think I can be reasonably confident now that the intake was repaired properly. I just didn't realize how horribly slow the stock ECU can sometimes be in raising the IAM. I wonder if some people are tracking their stock car at 0.7 IAM and don't even realize their engine is not at full power.

[steve99]

Originally Posted by VTEC

Thanks everyone. IAM rose really fast this morning. As soon as I got on the main road I gave it gas at low revs and it shot up to 1.0 before the engine even warmed up. Leaving work was another story. Was stuck in traffic for quite a bit and it wouldn't budge at all from 0.7. Even if I gave it gas in 1st and 2nd gear at low revs. Probably because it accelerates out of the low RPM range too quickly. But once the traffic cleared up and I could use low RPM in 5th and 6th gear the IAM shot up to 1.0 quickly again.

In both cases once the IAM reached 1.0, it never fell back down even under full throttle and high RPMs.

I think I can be reasonably confident now that the intake was repaired properly. I just didn't realize how horribly slow the stock ECU can sometimes be in raising the IAM. I wonder if some people are tracking their stock car at 0.7 IAM and don't even realize their engine is not at full power.

IAM is dropping as you must have significant knock for the tune and fuel combination your using. The stock tune is very knock prone arround 2000-4000 rpm under medium to high loads on anything but the best fuel.

most tuner roms are significantly better in this area, you iam is dropping as its the ecu safety mechanism to protect engine when significant knock detected.

Try a different brand of fuel some are way better than others even with same octane rating

[Kodename47]

Originally Posted by steve99

IAM is dropping as you must have significant knock for the tune and fuel combination your using.

Originally Posted by VTEC

On stock tune, the ECU resets the IAM to 0.7 on startup which I've searched here is normal.

[steve99]

Originally Posted by Kodename47

assumed his iam was 1 then dropped in traffic to 0.7 while driving :-)


also on my tuned roms (iam initial set to =1 ) if iam dropped below 1 I could never reset it to one by just turning ignition off, had to drive it and do a couple of light throttle runs.


assume this will be same for stock rom ? ie 0.7 initial after flash/reset, but then ecu remembers last iam reading on startup.