Digital Tuning Idling Characteristics/power In Cooler Weather.

Hi all!

I own a 2007 GT with a FRPP CAI, Steeda Billet Delete plates, Kooks LT headers, O/R X-pipe and Pypes SS exhaust. I'm using a Bama Tunes SCT X3 tuner with a 93 octane w/deletes tune. The car runs great, but I have a few questions:

1. On a cold startup the car will idle around 1500 rpm and drop down slowly over the course of a couple of minutes to 750 rpm. While it's at 1500 rpm it is VERY loud at the tailpipe, but it's almost as if something is closing after a few seconds and the sound quitens considerably. After it drops to 750 rpm I can push the throttle and take it back to 1500 rpm, but it is no where near as loud as it is on the initial cold-start idle(1500 rpm) after a cold start. Anyone have any ideas what is different between the cold start idle at 1500rpm, and throttle induced rev to 1500?

2. Seeing as I'm running the bama 93 octane w/deletes tune, should there be a noticable difference in power on cooler days? Where I live it has recently been dropping down into the high 50's/low 60's at night, and I can feel a noticeable increase in power while driving at these outside temps. Now, I know about colder air having a denser air charge, but wouldnt a colder incoming air charge cause the PCM to adjust accordingly due to the O2 sensors telling the PCM to adjust fuel delivery due to the change in burn with the colder, denser air??

Many thanks in advance to anyone who can shed some light on these questions.
 
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Now, I know about colder air having a denser air charge, but wouldnt a colder incoming air charge cause the PCM to adjust accordingly due to the O2 sensors telling the PCM to adjust fuel delivery due to the change in burn with the colder, denser air??

Think about that for a minute... Let's say that you're driving down the road and all the sudden, the air becomes 30 degrees colder. As you suggest, the o2 sensors indicate more free air to the PCM. So what do you think the PCM is going to do? It's going to add MORE fuel. Your air intake temps sensor and knock sensors are going to add more timing. What do you think the result of MORE fuel and MORE timing is going to be? :D

As far as the problems you've asked about in your post, I would suggest that your tune and/or tuner are the root cause of your high idle at start problem. Your smog pump and thermactor solenoids can account for the additional noises you hear at cold start up as air is injected into the catalytic converters to get them up to operating temperature.
 
I think I phrased my 2nd question wrong..

I understand that colder air will resort in more power, but what I'm trying to understand is how the actual tune itself would allow for such a wide variance in performance based solely on the ambient air temperature as the only differing variable. If I am mistaken please correct me, but doesnt the tune loaded in the PCM(as provided by Bama) set finite operating parameters into the PCM, based on the addition of the aftermarket items that were installed(CAI, Delete plates, headers, x-pipe and exhaust)? I guess my question is: The aftermarket(Bama) tune takes into account the aftermarket items I mentioned which allow for more airflow(hence more fuel/timing ect.), but what functions are at work in the PCM that allows it to increase fuel/timing..ect that allow for more power when the air is colder, versus what the tune/PCM controls when the air is warmer, when using the same tune?
 
I think I phrased my 2nd question wrong..

I understand that colder air will resort in more power, but what I'm trying to understand is how the actual tune itself would allow for such a wide variance in performance based solely on the ambient air temperature as the only differing variable. If I am mistaken please correct me, but doesnt the tune loaded in the PCM(as provided by Bama) set finite operating parameters into the PCM, based on the addition of the aftermarket items that were installed(CAI, Delete plates, headers, x-pipe and exhaust)? I guess my question is: The aftermarket(Bama) tune takes into account the aftermarket items I mentioned which allow for more airflow(hence more fuel/timing ect.), but what functions are at work in the PCM that allows it to increase fuel/timing..ect that allow for more power when the air is colder, versus what the tune/PCM controls when the air is warmer, when using the same tune?

I think you're under the impression that the PCM is designed to send X fuel and Y spark at Z RPM under B load. If that were the case, there'd be no reason to have a PCM at all.

Every PCM out there has an adaptive control strategy. It allows your car to run efficiently based on conditions. Tempurature, Barometric pressure, Humidity, engine condition, etc... It wouldn't really be worth having if all it did was pick a one-line fuel table and spark table and run that same setup for every condition.

Temprature is HUGE. That one aspect dictates how the other two (baro pressure and humidity) are going to effect overall output.

...and No. The PCM doesn't look at and/or rate your final power output. It doesn't say, "Oooops... that's 400 HP to the flywheel, that's all you get".
 
My bone-stock '06GT has a "fast" idle at startup, and gradually drops to normal ~750RPM after a short time. I think this is normal for most new(er) cars.

As Noobz stated, IAT (intake air temp) is huge for these engines. Cooler temps = mo' fun. It's been nothing but ballz-hot here since I got my car; I'm looking forward to seeing how it runs once the temps drop off some.
 
Thanks Noobz347!

I guess what I'm having trouble understanding then, is what exactly an "updated aftermarket tune" is changing, especially with this "adaptive control strategy" that you mention. Why even change the tune if the PCM is going to adaptively react to more airflow as a result of the bolt ons that have been installed on my car??

I'm assuming here that the tune was developed on a dyno at whichever location bama developes it tunes, where the temp, barometric pressure and humidity are different from my geographical location. So if I'm understanding this correctly, then it seems like a tune is developed with a "best guess" set of parameters based on what temps, bar. pressure and humidty the end user of their tune will experience...?? And if that's the case, then it would seem that to maximize performance it would be advantageous to have a summer tune, and a winter tune(both developed local to me) to take advantage of the wide temperature variations that I experience where I live...???
 
I think you're "overthinking" this a bit. There are lots more parameters than just temp/pressure/etc that are getting changed with a tune. Factory programming is going to still be on the very conservative side, and not really change things like throttle response, shift points (for autos), etc. An aftermarket tune is going to get the most out of the engine based on the conditions at present. It can still adjust for different temps/pressure/etc on the fly. Without being a programmer, we have no idea what all parameters are getting changed. I bet if you called AM or someone like that they would be able to give a lot more detail on what all gets changed.
Think about it - take your car back to stock and drive it for a while. Then flash your aftermarket tune back. There's a lot more going on than just timing advance for a few extra ponies.
 
Thanks Noobz347!

I guess what I'm having trouble understanding then, is what exactly an "updated aftermarket tune" is changing, especially with this "adaptive control strategy" that you mention. Why even change the tune if the PCM is going to adaptively react to more airflow as a result of the bolt ons that have been installed on my car??

I'm assuming here that the tune was developed on a dyno at whichever location bama developes it tunes, where the temp, barometric pressure and humidity are different from my geographical location. So if I'm understanding this correctly, then it seems like a tune is developed with a "best guess" set of parameters based on what temps, bar. pressure and humidty the end user of their tune will experience...?? And if that's the case, then it would seem that to maximize performance it would be advantageous to have a summer tune, and a winter tune(both developed local to me) to take advantage of the wide temperature variations that I experience where I live...???

Yes and no. The ONLY WAY (read: only way) you're going to get an optimum tune for YOUR vehicle is to get it dyno-tuned. What you said about Bama tunes being a BEST GUESS is absolutely and 100% true! They have experimented and discovered that THIS particular 93 octane tune works on 95% + of cars with X mods. They rely on the adaptive strategy to take care of the rest.

That said... I still don't think you understand what these tunes are. When your car comes from the factory, the PCM comes programmed and designed to run your vehicle efficiently and meet smog standards. The PCM is designed with a program that knows how to interpret and what do with the fuel/air tables, spark tables, and sensor input data. THAT is the program. When you get a car tuned, the PROGRAM is not changed. What is changed are the TABLES that the program pulls data from to make it's adjustments. Some examples of those tables are:

Fuel ramp - for open loop, for closed loop, for X temperature range, for y temperature range, power setting, load, and the list goes on
Injector pulse width
Spark tables - There are almost as many spark tables as there are for fuel
Spark advance tables
....and the list goes on.

So when you isntall a performance tune, you're rarely changing the PCM's method of doing business. What you're doing is installing more aggressive fuel and spark tables etc. for the PCM to use in running the motor. The PCM still makes changes based on sensor input and environmental conditions. Those adaptive strategies can be locked out but you will generally only see tha happen on race specific applications where that car was last tuned just before lining up.
 
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Noobz347,

My apologies for the late reply, but temporarily working 3rd shift right now kinda messes with my sleep! :ack:

At any rate, thank you so much for taking the time to explain this in the way that you have! Since your last post I've done a lot of searching and reading to get up to snuff with the PCM and programming/tunes in these animals. I'm close to 50, so my younger(racing) days were spent tinkering with Carbs, turning the distributor and a slew of other tricks I used when I went to the track. There was none of this programming stuff back then. I didnt realize just how out of touch I was until I started wondering/asking about this new stuff...jeeze..now I feel old! heh:zombie:

Nice to know there are helpful and courteous people on this forum! Thanks Again!
 
Noobz347,

My apologies for the late reply, but temporarily working 3rd shift right now kinda messes with my sleep! :ack:

At any rate, thank you so much for taking the time to explain this in the way that you have! Since your last post I've done a lot of searching and reading to get up to snuff with the PCM and programming/tunes in these animals. I'm close to 50, so my younger(racing) days were spent tinkering with Carbs, turning the distributor and a slew of other tricks I used when I went to the track. There was none of this programming stuff back then. I didnt realize just how out of touch I was until I started wondering/asking about this new stuff...jeeze..now I feel old! heh:zombie:

Nice to know there are helpful and courteous people on this forum! Thanks Again!

No problem... Getting your head wrapped around the initial concept can be the hardest part. There are LOTS of people that have never known anything but fuel injection and still have no idea how it works. Many think that when you get a car "tuned" that's like changing from a MAC operating system to PC. All you're really doing is making changes to the tables of data stored in the PCM so that when it sees X, it bumps it against the values in the tables and does Y. Custom tunes are designed to work higher into that margin of safety built into those tables by the OEM.
 
So when you isntall a performance tune, you're rarely changing the PCM's method of doing business. What you're doing is installing more aggressive fuel and spark tables etc. for the PCM to use in running the motor. The PCM still makes changes based on sensor input and environmental conditions. Those adaptive strategies can be locked out but you will generally only see tha happen on race specific applications where that car was last tuned just before lining up.[/quote]

Noobz - can I ask a stupid question? - I have mutha thumprs in my 07 GT (NSR) - and Only when I turn my A/C on does it ramp up the rpms - like someone is pushing on the gas - won't kick down for nothing ...I mean eventually it will when it comes to a complete stop - it idles normal - anything I can do by myself?....I have a SCT breendspeed tune - they say they won't even look at the mutha thumpr's anymore / no service - they tried to fix it but no - I did look into the dyno tune - but the guy said I have to start from scratch and buy a tuner from him if I want him to it on dyno - wtf? - I'm not trying to squeeze out any HP - just want it to run decent .........didn't mean to hijack this thread ......but this is driving me :crazy:
 
Noobz - can I ask a stupid question? - I have mutha thumprs in my 07 GT (NSR) - and Only when I turn my A/C on does it ramp up the rpms - like someone is pushing on the gas - won't kick down for nothing ...I mean eventually it will when it comes to a complete stop - it idles normal - anything I can do by myself?....I have a SCT breendspeed tune - they say they won't even look at the mutha thumpr's anymore / no service - they tried to fix it but no - I did look into the dyno tune - but the guy said I have to start from scratch and buy a tuner from him if I want him to it on dyno - wtf? - I'm not trying to squeeze out any HP - just want it to run decent .........didn't mean to hijack this thread ......but this is driving me :crazy:

I didn't see your post until just now because the quote tags didn't post correctly.

If I'm reading your post correctly, you're running a tuner that nobody currently provides support for? If that's true then it's time to get another tuner.

I recall seeing tables that add/subtract fuel and timing depending on whether air cond was active or not. Without the ability to look at those tables yourself, you're pretty much screwed. The only other thing that I can think of would be to get a wiring diagram and locate the signal wire responsible for telling the EEC that the A/C switch is on. You could thoretically cut and cap that wire to prevent the motor from idling up when it's on. If you choose to go this route, make sure you do it so that it can be easily undone if you don't like the seide effects.
 
I didn't see your post until just now because the quote tags didn't post correctly.

If I'm reading your post correctly, you're running a tuner that nobody currently provides support for? If that's true then it's time to get another tuner.

I recall seeing tables that add/subtract fuel and timing depending on whether air cond was active or not. Without the ability to look at those tables yourself, you're pretty much screwed. The only other thing that I can think of would be to get a wiring diagram and locate the signal wire responsible for telling the EEC that the A/C switch is on. You could thoretically cut and cap that wire to prevent the motor from idling up when it's on. If you choose to go this route, make sure you do it so that it can be easily undone if you don't like the seide effects.

thanks Noobz !.....I understand ...sooner or later the AZ emissions is gonna find my silly ass and I'll have to do (2) tunes - (1) one to de tune it / pass it and then another to reinstall everything - before that I'll get the new tuner and dyno it - .....so it's cool - thought you may have some 'black' magic remedy for me .....it's very nice in the morning's in the mustang - driving it back at 5PM in the 115 degree heat - no A/C ............. :eek: !!!!!!!!!!!!!!