To Tune or not to Tune

[mlee]

Originally Posted by Rhino79

The MAF doesn't adjust anything. Its just a meter to report air measurement and temp. Fuel will be adjusted in closed loop yes, but thats via o2 feedback. The MAF table is precalibrated for the factory induction(its not even dead on for it). Once you change flow before or more importantly after it, it effects the readings. Do you have to tune, no. For best results and accuracy, yes tune it.

Agree and this makes sense... I didn't mean so say the MAF made the adjustments but everytime the MAF is moved or airflow changes air fuel automatically updates to account for it... and this is outside closed loop.

[Steck]

The car does not tune itself. Closed loop applies a fuel trim to various cells of operating conditions. The PCM does not adjust anything in open loop. Open loop is based purely off of preprogrammed values (hence the term open loop). The only close loop function that impacts WOT is a positive long term fuel trim, which will carry into power enrichment.

[mlee]

Not disputing anything but why do they tell you to drive your car for 20 or 30 min to learn the new settings..?

[mgoodbar]

Well this concerns me...... The maf would have to give some sort of + or - range... They all get dirty correct? I have a tune from Ted... It is can tune with some data loging..... how ever my tune was writen 3 months ago.. now its cold out side so the air is dencer. I have not cleaned my Maf since I installed my K&N... So since there are so many changes in my system over the past couple months, does this mean I need to bother Ted with more data loging, jut to make sure my calibration is not off?????? I would hate to wast a A6 just for a little dirt and temperature change......

[Ventmaster]

Originally Posted by Steck@Craven

A cold air intake impacts the MAF housing. This throws the MAF calibration off, consequently skewing torque reporting.

While technically correct, I believe you're splitting hairs here, and possibly throwing the baby out with the bath water (sorry, two metaphors in the same sentence).
You may convince some folks that already have light mods to tune- but just as many (or more) will decide to take the "hands off" approach and leave their vehicles stock. Then no one makes any money.

Horsepower is habit forming, but you have to take the first step, make a few changes that often lead to more changes- the kind that require a tune.

My Dad taught me 3 things:
1) Don't shit in your own nest.
2) Never hit a women.
3) Never- ever mess with another man's income.

[mgoodbar]

I agree with the above..


+ never touch another mans FRIES. or woman....

[Rhino79]

The air quality, air temp, air desity, is taken care of by the MAF. The more dense the air is, the more air it will consume, it will run higher on the maf table (higher frequency reported to ecm). They say drive for 20-30 mins to learn for idle adapts, coastdown adapts, trans adapts, and Fuel trim adapts.

Heck no you aren't going to destroy your trans by not tuning the ecm after a cai. Super pickey people like myself don't like running a setup that isn't as accurate though. Sure fuel trims will pick up the slack and you'll never know the difference in most cases.....until an 02 goes out or for some reason you are forced into open loop where there is no fuel trimming.

I don't want my car running good on 10% fuel trims, I want it running good on 2-3% trims. To each their own though.

[Steck]

Originally Posted by mlee

Not disputing anything but why do they tell you to drive your car for 20 or 30 min to learn the new settings..?

To adapt the fuel trims during part throttle driving. That's the brunt of it.

Originally Posted by mgoodbar

Well this concerns me...... The maf would have to give some sort of + or - range... They all get dirty correct? I have a tune from Ted... It is can tune with some data loging..... how ever my tune was writen 3 months ago.. now its cold out side so the air is dencer. I have not cleaned my Maf since I installed my K&N... So since there are so many changes in my system over the past couple months, does this mean I need to bother Ted with more data loging, jut to make sure my calibration is not off?????? I would hate to wast a A6 just for a little dirt and temperature change......

Your tune from Ted is fine. The MAF doesn't care about temperature or air density. It purely reads the mass flow rate of incoming air. It is a pretty nice tool for metering air flow.

Originally Posted by Ventmaster

While technically correct, I believe you're splitting hairs here, and possibly throwing the baby out with the bath water (sorry, two metaphors in the same sentence).
You may convince some folks that already have light mods to tune- but just as many (or more) will decide to take the "hands off" approach and leave their vehicles stock. Then no one makes any money.

Horsepower is habit forming, but you have to take the first step, make a few changes that often lead to more changes- the kind that require a tune.

My Dad taught me 3 things:
1) Don't shit in your own nest.
2) Never hit a women.
3) Never- ever mess with another man's income.

Some CAIs are worse offenders than other. If the car's trims end up +/- 5%, it's probably fine. However there are some out there that can drastically change the MAF calibration which WILL waterfall into the A6.

I tune minor changes because I can. It also costs me nothing except my time. I just think people are really missing out by throwing parts on and not taking full advantage, especially when there is a possibility of other ill effects. I'm also the same person who doesn't care about voiding warranties (and wants nothing to do with warranty fraud either). When the C7 comes out, I'll have one with a voided warranty two weeks after bringing it home.

Originally Posted by Rhino79

The air quality, air temp, air desity, is taken care of by the MAF. The more dense the air is, the more air it will consume, it will run higher on the maf table (higher frequency reported to ecm). They say drive for 20-30 mins to learn for idle adapts, coastdown adapts, trans adapts, and Fuel trim adapts.

Heck no you aren't going to destroy your trans by not tuning the ecm after a cai. Super pickey people like myself don't like running a setup that isn't as accurate though. Sure fuel trims will pick up the slack and you'll never know the difference in most cases.....until an 02 goes out or for some reason you are forced into open loop where there is no fuel trimming.

I don't want my car running good on 10% fuel trims, I want it running good on 2-3% trims. To each their own though.

This pretty much covers it. I have seen some intake setups that throw trims WAY off though. That indicates a serious problem to me (a problem that is easily corrected).

[ParisTNDude]

IMO, there are plenty of CAIs that will not cause a check engine code. My Kooks LT headers and HF cats didn't cause a code as well. Considering the high cost of a dyno tune, I would wait until you decide to put LT headers on the car (trust me, you will), then get a tune. There's a thread posted where one of the C5 members put a law suit on GM for failing to honor the warranty when the faulty item could not have been impacted by performance parts and the C5 GM settled out of court and paid (plus court costs). You should find that and read it, it's very enlightening!

[tooslow]

Just a general question, but since you see threads show up like this all the time, how many people are in then position of owning a performance vehicle but not having the financial resources to deal with a repair should something happen with their modified car? I mean, if your finances are that tight and you need the warranty to cover you if something were to run afoul, why mod in the first place?

To the OP, if not having a power train warranty is a concern, then the answer is easy; don't do it.

[Steck]

Originally Posted by tooslow

Just a general question, but since you see threads show up like this all the time, how many people are in then position of owning a performance vehicle but not having the financial resources to deal with a repair should something happen with their modified car? I mean, if your finances are that tight and you need the warranty to cover you if something were to run afoul, why mod in the first place?

To the OP, if not having a power train warranty is a concern, then the answer is easy; don't do it.

[sschevybear11]

I've added LT's and no cats just before storage and love the gain but it came with a CEL that I knew would happen. Bought a used, unlocked SCT cheap and was getting a tune from ted after the christmas pain is over. I'm on the fence about a CAI because I had a vararam and even after a 100 miles in better weather at the track it lost maybe a tenth so I sold it.This makes me think that tests are done directly after install and the lean out is the gain. Who knows?

[geaux_tigerss]

Originally Posted by Steck@Craven

Your tune from Ted is fine. The MAF doesn't care about temperature or air density. It purely reads the mass flow rate of incoming air. It is a pretty nice tool for metering air flow.

It reads mass and velocity then multiplies by a constant to calculate volume. I assume when you say "calibrating the MAF" you mean adjusting this constant to account for a different cross sectional area in the flow measurement location between the stock intake and an aftermarket.

[mgoodbar]

yep changing the constant