MAF housing sizes and timing pull..

[GolfRS]

Chris, i've always thought adaptation itself if the effort made by the ECU to reach a new equilibrium (meaning zero STFT and LTFT ), after having been reset, or when any of the hardware has changed.

A fuel trim that stays above zero, kinda defeats the above procedure.No ?

Are there stock cars with stock software that log a positive (or negative) trim value after adaptation has ended?And if so, what is the reason for that.

P.S.Somehow i've seen my car change trims all the time.Thats both STFT and LTFT.It usually reaches 4 to 5%....

 

[Chris@RT]

The number is showing the adaptation that is the point of it. A car is always going to show a number other then 0. It doesn't adapt too 0 it adapts away from 0.

Your car showing 4-5% doesn't mean its constantly changing it means that is what it changed too in order to reach its goal...it now has "equilibrium"

This is why when you clear the codes it goes to 0.. It has erased all the adaptation and must start over, it adapts from there. As you watch the numbers change its still adapting. After a week when it settles at 1% and 5% its finished adapting. IT will still change and adapt constantly as fuel changes and other conditions change.

The car will reach a point however when too much adaptation means too much which is why when you hit higher limits it yanks all your timing.

 

[g_berserk]

The fujita is the worst offender

Have something to back-up that statement?

I have installed a Fujita intake and didn't felt any decrease in power or running lean, contrary, the car seem to be runing a bit richer than it used to... no power gains either, just funny stuff :iono: but I love the sound.

How can I log my pulltimes to see how off are they?

 

[Chris@RT]

You wouldn't notice if it runs leaner or richer unless you are pegging the adaptation. The car will run whatever the requested fuel is with or without the intake, the intake isn't going to change the actual resulting mixture. It will change what the car does to achieve that same mixture. That is the adaptation.

 

[jeffc31337]

This is a great technical discussion!

My question is in regards to the statements about the "load" paramater and how the car really is trying to reach a specified load and adjusting boost/timing/ etc is just a by product of trying to hit that load. Is there a way to actually vag-com what the specific load is or is that masked in some way?

I have completely stock hardware with a GIAC flash and was planning on doing some logging before and after installing a bsh intake next weekend. What blocks would be useful to log to get a good picture of before and after? Load, stft, ltft, boost, overall timing and correct factor? (could someone tell me what blocks are load, stft, ltft?) I'd be happy to grab stock settings and post them up to this thread of anyone think it would be a useful point of reference.

 

[KaJ]

This is a great technical discussion!

My question is in regards to the statements about the "load" paramater and how the car really is trying to reach a specified load and adjusting boost/timing/ etc is just a by product of trying to hit that load. Is there a way to actually vag-com what the specific load is or is that masked in some way?

I have completely stock hardware with a GIAC flash and was planning on doing some logging before and after installing a bsh intake next weekend. What blocks would be useful to log to get a good picture of before and after? Load, stft, ltft, boost, overall timing and correct factor? (could someone tell me what blocks are load, stft, ltft?) I'd be happy to grab stock settings and post them up to this thread of anyone think it would be a useful point of reference.

I'd do 32 for fuel trims, 20 for timing pull, and 115 for boost. Block 11 is overall timing and 31 is A/F ratio.

I'd be interested in seeing before and after logs for the bsh intake.

 

[itisagoodname]

From what i've been reading load is generally calculated Load=(MAF* constant)/RPM

And it almost seems that that constant may be the 1+LTFT. Normally my MAF readings would be around 200g/s... when i switched to the BSH DV re-route my LTFT's went to 14% and my MAF readings dropped around 30g/s. +/- a few g/s... 14% of those 200g/s is 28g/s.

So plotting specified vs actual load... the lower MAF readings would be have to be adjusted by X to achieve the specified load.

(200g/s*1)/RPM=(175g/s*1.143)/RPM :: LTFT being +14.3%

Any thoughts??

 

[itisagoodname]

I'd do 32 for fuel trims, 20 for timing pull, and 115 for boost. Block 11 is overall timing and 31 is A/F ratio.

I'd be interested in seeing before and after logs for the bsh intake.

Block 114 Is also Specified and Actual Load along with wastegate duty cycle.

Before BSH Intake:




After BSH Intake

 

[jeffc31337]

Just to reinforce what Chris was say about adaptation starting at 0 and working up my LTFT on a TT with 100% stock hardware(even the air filter) is -1.6%.

I should be putting on the BSH intake next weekend and will log all the interestin paramaters.

My only real concern is with the welds on the BSH as there is one just upstream of where the MAF sits. I can't see the inside of the tube there but the weld on the front part of the intake tube has seep into the intake that portrudes 3-4 millimeters into the air path about 50 percent of the way around the tube. I'd have to assume the weld near right near the MAF has something similar and wouldn' this possibly cause very turbulent air and possibly screw up MAF readings?

 

[itisagoodname]

Just to reinforce what Chris was say about adaptation starting at 0 and working up my LTFT on a TT with 100% stock hardware(even the air filter) is -1.6%.

I should be putting on the BSH intake next weekend and will log all the interestin paramaters.

My only real concern is with the welds on the BSH as there is one just upstream of where the MAF sits. I can't see the inside of the tube there but the weld on the front part of the intake tube has seep into the intake that protrudes 3-4 millimeters into the air path about 50 percent of the way around the tube. I'd have to assume the weld near right near the MAF has something similar and wouldn' this possibly cause very turbulent air and possibly screw up MAF readings?

You are correct... the welds are ugly and the inside of the tubing is not so smooth at all...

 

[281CJ]

Deviation, smeviation.

ANY change in the size of the MAF housing or placement of the MAF requires a Retune for the car to run the proper A/F, trims, and timing. Most cars the intake replaces everything between the MAF and TB, which means that no retune is needed as the MAF is still calculating correctly.

On a GTI is seems an intake replaces everything from filter-to-TB, which means that even if its the same size piping the MAF may still need to checked to insure that it is accurate. Which implies that ANY intake change on a GTI almost requires and A/F check and possible a recalibration of the MAF.

The PCM does NOT recalculate the MAF reading, it assumes the MAF is correct to calculate for say a change in exhaust or, a intake AFTER the MAF. It uses the MAF as a standard, and if the MAF is wrong so are all its calculations.

The VERY first thing any tuner will do is make sure the MAF is correctly calibrate, then work from there.

 

[petsy]

Just to reinforce what Chris was say about adaptation starting at 0 and working up my LTFT on a TT with 100% stock hardware(even the air filter) is -1.6%.

My trim numbers are -0.4% and -4.7% with the stock airbox and ITG drop in filter.

 

[first350]

does the GTI go into open-loop while @ WOT?

I assume it's closed loop for everything else - which should be sufficient to account for small deviations in MAF readings...wouldn't it just look at the exhaust O2 sensor and adjust fuel to hit it's desired AFR.

 

[281CJ]

does the GTI go into open-loop while @ WOT?

I assume it's closed loop for everything else - which should be sufficient to account for small deviations in MAF readings...wouldn't it just look at the exhaust O2 sensor and adjust fuel to hit it's desired AFR.

Many cars do that, but they use the MAF to base the calculation for how much Fuel to add in, so while it may eventually figure out how much fuel to add, it may not realize it's just compensating for a poorly calibrated MAF.

Basicly it comes down to:
Car thinks it needs to run 12.7a/f
MAF tells car its pulling (this much) air
Car adds fuel to compensate for (this much) air
Car thinks its now running 12.7

Car goes on dyno and is really running 13.3
Tuner recalibrate's MAF
Car now runs 12.7 after added the extra fuel it needed
You go home happy with a safer running car, and the added in timing from having a better(slightly richer) a/f mix.

 

[Chris@RT]

Deviation, smeviation.

ANY change in the size of the MAF housing or placement of the MAF requires a Retune for the car to run the proper A/F, trims, and timing. Most cars the intake replaces everything between the MAF and TB, which means that no retune is needed as the MAF is still calculating correctly.

On a GTI is seems an intake replaces everything from filter-to-TB, which means that even if its the same size piping the MAF may still need to checked to insure that it is accurate. Which implies that ANY intake change on a GTI almost requires and A/F check and possible a recalibration of the MAF.

The PCM does NOT recalculate the MAF reading, it assumes the MAF is correct to calculate for say a change in exhaust or, a intake AFTER the MAF. It uses the MAF as a standard, and if the MAF is wrong so are all its calculations.

The VERY first thing any tuner will do is make sure the MAF is correctly calibrate, then work from there.

It does not require a retune because as pointed out numerous times in this thread the car is able to adapt. That is the long term fuel trims. However once it maxes those out or starts to push them it will pull back just for safety sake.

We have a wideband 02 sensor stock it remains closed loop the entire time, idle, pat throttle, WOT making adjustments. To the fueling.


The MAF does play a roll but with the wideband in there you can run one of these cars exactly the same with and without a maf..



overly simplified version.. maf reads car injects fuel 02 sensor says ok or not ok.. ECM adjusts if need be.

02 gets final say and corrects things.. car "self tunes"