ECU Fighting Mods?

[ChazSpeed]

I read over on the "other" forum that the ECU will get used to mods on the car over time, and level out the fuel and air to even out the car again. So once I install a CAI, and a TBE, it will perform well at first, but over time the gains from the extra air flow will get evened out by the ECU compensating accordingly to try to bring it down to stock levels.

Is this true? And if so, how do you keep it from happening, or do you just reset the ECU by unhooking the battery?

 

[Haltech]

I read over on the "other" forum that the ECU will get used to mods on the car over time, and level out the fuel and air to even out the car again. So once I install a CAI, and a TBE, it will perform well at first, but over time the gains from the extra air flow will get evened out by the ECU compensating accordingly to try to bring it down to stock levels.

Is this true? And if so, how do you keep it from happening, or do you just reset the ECU by unhooking the battery?

Thats the biggest horseshit ive heard around here. Ignore it, its completely false...

 

[numbnuts22715]

yeah.. Ive never heard of that either..
Ive heard of it fighting like a piggyback a little bit, but not completely... Thats ridiculous.

 

[ChazSpeed]

That is what I was hoping people would say, here is the quote that made me wonder though:

We now understand that we can allow the turbo to pull air easier by cutting down on certain restrictions from the intake end and exhaust end. But there's one important thing to keep in mind. Every flow measurement (air, fuel, timing, boost, etc...) is constantly being monitored by the ECU. It is programmed to run at specific Air/Fuel ratios. And the stock A/F ratio is VERY rich (meaning excess fuel). So even if you INCREASE the air coming in and assume its leaning out. Yes, it is, slightly... But the ECU will eventually correct itself once it detects an out-of-norm ratio, or a knock. This is why people are told to RESET their ECU after adding a modification. So as soon as you punch the throttle, you will feel a VERY notable difference... but as time goes on, that ecu will have retarded timing and adapted to the change.

My advice is simple: Each mod you add mentioned above will give you a gain. How much of a gain is to be taken with a grain of salt. Dyno's show an immediate pull, not an adapted pull. Take horsepower and torque graphs for what they are, but do not expect these gains to add up perfectly. Overtime these parts that you spend money on will no longer do what they used to, because your ECU will not allow it. Just because an intake is CAPABLE of drawing more air in, doesn't mean it will.

To get the MOST out of your mods, or even the most out of your vehicle in stock trim, invest in a good Engine Management option.

 

[desperado-c]

That is what I was hoping people would say, here is the quote that made me wonder though:

Who is the quote from? I don't think it is BS. Isn't the function of the ECU to try to keep things within set parameters? Doesn't mean every mod will be totally defeated, just that something like leaning out the mixture by increasing intake airflow will likely be moderated by ECU adjustments to long-term trims. So a big initial gain in power on the dyno right after the intake was added might be gradually moderated.

 

[mazdaspeedjay]

yes but only to a certain extent and it can only do so much. i put a home made boost controller on my MS3 everyone said after like two weeks the ECU or PCM what ever would correct it and my boost would go back to stock since my controllers work with the factory solenoid or is used with the factory solenoid. i'm going on almost a month and still same boost. the MS3 learn and can learn and may change a few things but if you put a CAI SRI and a TBE it will perform the same everytime except for the usual where and tear on the engine from driving it.

What this is all about i believe is the whole i'm getting use to me car problem or my car doesn't feel as fast anymore. you mod it and it feels great and if you drive your car everyday eventually you get use to the feeling and the car doesn't feel as fast anymore. i've felt that when u had my SRT4. i left for training for two weeks and when i got back the first thing i did was drive my car and it felt totally newish again. lol

 

[matsuda]

The bottom line is that you cannot change the AFR with a mod like a CAI for example. If your new CAI causes your engine to run leaner after installation, the ECU will compensate and keep the learned data in memory.

That is not to say that there is no advantage to installing a good intake.

 

[Jays07MS3]

The bottom line is that you cannot change the AFR with a mod like a CAI for example. If your new CAI causes your engine to run leaner after installation, the ECU will compensate and keep the learned data in memory.

That is not to say that there is no advantage to installing a good intake.

I can see the ECU compensating at partial throttle (closed loop) but not at WOT (open loop). As far as I understand it, during open loop operation the ECU only takes into account MAF, IAT, and MAP sensors not O2 readings. So the ECU really shouldn't be messing with things at WOT but I'm not 100% sure of this.

 

[Haltech]

The bottom line is that you cannot change the AFR with a mod like a CAI for example. If your new CAI causes your engine to run leaner after installation, the ECU will compensate and keep the learned data in memory.

That is not to say that there is no advantage to installing a good intake.

Most certainly you can! As much as i want to believe our beloved MS3's have adaptive correction tuning ( self correcting depending on mods ), thats not true. Ive seen in my own actual test, the stock intake setup vs the MSCAI, the MSCAI does lean out the car a bit. First of all, i think this was done on purpose to get more torque out of the car. Second, the computer has NOT corrected its lean state. Ive been monitoring this over the past 6 months and i still see the +.3 increase in overal AFR on this car with the MSCAI.

 

[desperado-c]

Most certainly you can! As much as i want to believe our beloved MS3's have adaptive correction tuning ( self correcting depending on mods ), thats not true. Ive seen in my own actual test, the stock intake setup vs the MSCAI, the MSCAI does lean out the car a bit. First of all, i think this was done on purpose to get more torque out of the car. Second, the computer has NOT corrected its lean state. Ive been monitoring this over the past 6 months and i still see the +.3 increase in overal AFR on this car with the MSCAI.

You dare to question the Oracle of Mazda, Matsuda-san?

 

[Haltech]

You dare to question the Oracle of Mazda, Matsuda-san?

Damn straight.. If we had adaptive tuning, why the hell are we waiting for the Cobb AP.. Catch my drift? Enough said.

 

[matsuda]

I can see the ECU compensating at partial throttle (closed loop) but not at WOT (open loop). As far as I understand it, during open loop operation the ECU only takes into account MAF, IAT, and MAP sensors not O2 readings. So the ECU really shouldn't be messing with things at WOT but I'm not 100% sure of this.

You have a good point but...

The long term fuel trim for high load conditions that the ECU learns in closed loop mode is applied during open loop operation. If the intake is well designed, the airflow at the MAF sensor will have a perfectly linear relationship to the real airflow and the ECU can properly correct any lean or rich tendencies by adjusting the long term fuel trims. For example, an intake with a slightly larger MAF housing will at first cause the engine to run leaner until the ECU "learns" and compensates by setting the long term fuel trims to a more positive value. In open loop mode, more fuel would now be added and the AFR would be identical or at least close to that of a stock airbox.

 

[matsuda]

Most certainly you can! As much as i want to believe our beloved MS3's have adaptive correction tuning ( self correcting depending on mods ), thats not true. Ive seen in my own actual test, the stock intake setup vs the MSCAI, the MSCAI does lean out the car a bit. First of all, i think this was done on purpose to get more torque out of the car. Second, the computer has NOT corrected its lean state. Ive been monitoring this over the past 6 months and i still see the +.3 increase in overal AFR on this car with the MSCAI.

Pish posh.

You know, I wish that we could tune the AFR with an intake but it just doesn't work.

Compare long term fuel trims between a stock airbox and a MSCAI. There is a big difference. If you reset the ECU, the engine will run rich with a stock airbox and lean with a MSCAI. After the fuel trims are learned, it all evens out.

I've logged AFR's of richer than 10:1 with a MSCAI so it's really not leaning out the AFR. Of course at any given point in time, the AFR may be somewhat leaner than that of a stock airbox for any of the following reasons:

1) The ECU was recently reset.

2) Long term fuel trims normally vary for a variety of reasons. You may see a LTFT of +5% one day and +7% the next. This will of course affect the AFR at WOT.

3) The MSCAI is not necessarily the most well designed intake. It has no air straighteners and the MAF is located close to a bend in the tubing. It is likely that this would cause some turbulence which would mean that the real airflow and "MAF airflow" don't always correspond perfectly.

BTW, it is not possible that the MSCAI would cause the AFR to be leaner or richer overall unless the ECU decided to ignore the O2 sensors altogether. Regardless of the intake, the AFR will always be referenced to the O2 sensors because catalytic converters want to see a stoichiometric AFR.

 

[dkswim]

are ECU dose not go into closed loop all that often with our wb o2 sensor.

 

[Mid_Life_Crisis]

So long term, the only reason that adding a better intake (or exhaust) will gain more power is that it makes it easier for the engine to move larger quantities of air/fuel, which produces more power. We aren't going to get a free correction of the air/fuel ratio thrown in for good measure.
I understand that this means that the larger diameter of the tube in the MS-CAI will temporarily lean the fuel mixture.
Will resetting the ECU by disconnecting the battery cause the power to come back for a day? If so, I can live with this. I have no problem hooking up a relay so my ECU is disconnected while the car is parked if it means I'll get more power from my MS-CAI.

 

[Haltech]

Pish posh.

You know, I wish that we could tune the AFR with an intake but it just doesn't work.

Compare long term fuel trims between a stock airbox and a MSCAI. There is a big difference. If you reset the ECU, the engine will run rich with a stock airbox and lean with a MSCAI. After the fuel trims are learned, it all evens out.

I've logged AFR's of richer than 10:1 with a MSCAI so it's really not leaning out the AFR. Of course at any given point in time, the AFR may be somewhat leaner than that of a stock airbox for any of the following reasons:

1) The ECU was recently reset.

2) Long term fuel trims normally vary for a variety of reasons. You may see a LTFT of +5% one day and +7% the next. This will of course affect the AFR at WOT.

3) The MSCAI is not necessarily the most well designed intake. It has no air straighteners and the MAF is located close to a bend in the tubing. It is likely that this would cause some turbulence which would mean that the real airflow and "MAF airflow" don't always correspond perfectly.

BTW, it is not possible that the MSCAI would cause the AFR to be leaner or richer overall unless the ECU decided to ignore the O2 sensors altogether. Regardless of the intake, the AFR will always be referenced to the O2 sensors because catalytic converters want to see a stoichiometric AFR.

Doesnt really matter at WOT mate... Stoich goes out the window at that point. Part throttle is the area we cant tune at yet and thats where stoich rears its ugly head. I really think mazda wanted to lean this car out at bit to give more torque, otherwise i believe they would of corrected this condition in the MSCAI long before it went into production. I also think mazda believed we wouldnt see the aftermarket support of controlling their beloved ECU since they locked it down so well, or they thought. So, fixing the AFR issue wasnt a bigdeal as it is to us now. I still believe someone can create a $24 air straightener made out of Actel composite to slide inside the CAI and would fix the condition.

 

[ChazSpeed]

Basically I want to know if it ends up being worth it to drop $1000+ on intake, exhaust, and TMIC? Does the power really get evened out, or is it just running more fuel to match the better air flow, therefore keeping power, but still running rich (IE not as much power as it could be if it kept running lean)?

 

[matsuda]

Basically I want to know if it ends up being worth it to drop $1000+ on intake, exhaust, and TMIC? Does the power really get evened out, or is it just running more fuel to match the better air flow, therefore keeping power, but still running rich (IE not as much power as it could be if it kept running lean)?

Without a doubt there are HP gains to be had without a tune. The AFR will still be very rich but the engine will breathe better.

 

[Mid_Life_Crisis]

Resetting the ECU to stock every night should restore the "temporary leaned out condition" that results in that WOW feeling when you get on the gas.
If these mods only work temporarily (in terms of air/fuel ratio) because the ECU eventually uses its various sensors to pick up on the results and change the maps to put things back where it thinks they belong, then resetting the ECU should work until it has time to learn the changes again.
How many miles of driving does this take? Does anybody know?

 

[matsuda]

Resetting the ECU to stock every night should restore the "temporary leaned out condition" that results in that WOW feeling when you get on the gas.
If these mods only work temporarily (in terms of air/fuel ratio) because the ECU eventually uses its various sensors to pick up on the results and change the maps to put things back where it thinks they belong, then resetting the ECU should work until it has time to learn the changes again.
How many miles of driving does this take? Does anybody know?

It's really not a good idea to reset the ECU every night.

1) Depending primarily on the intake, it may make the AFR richer or leaner after "learning".

2) The ECU may set some fuel trims in as little as a few miles of driving. Often times, it may overshoot on the initial settings which could temporarily make the AFR even more rich.