View Full Version : Wrong value of fuel consuption indicator after engine swap
augustmic
10-15-2018, 02:11 PM
Dear!
I have A4 B6 with swapped engine.
3.0 ASN was replaced by 1.8T BEX+ (250HP, 370Nm, 440cc BOSH injectors)
I have problem with FIS display. The fuel consuption shows wrong values.
For example:
FIS shows: 7,9 l/100km, but from calculation is 11,9 l/100km. (11,9 / 7,9 = 1,5)
FIS shows 8,4 l/100km, but there was 13,0 in real. (13 / 8,4 = 1,5)
I need 150% correction. (Instruments -> 03 -> allows 115% only!)
150% = 1,5 = 3/2 = 6/4 (6 cyl. vs 4 cyl.?)
Whad do You think about it?
EuroxS4
10-15-2018, 03:19 PM
You will need to adjust in ecu software.So you will need to read out software from ecu and edit accordingly.I believe you need to edit map KVB or map KRKTE.Realistically if KRKTE is accurate no need to change KVB.
Fast4esT
10-15-2018, 04:30 PM
mine has been wrong ever since the 630cc injectors
b6Hate4
10-15-2018, 06:03 PM
mine has been wrong ever since the 630cc injectors
Fuel consumption is calculated based on injector duty cycle.
augustmic
10-18-2018, 12:04 PM
Thank You guys.
I started to learn what the KRKTE is :)
I found the page:
http://nefariousmotorsports.com/forum/index.php?action=printpage;topic=2625.0
We will try to do that, but if You have any other suggestions, please feel free :)
Nollywood
10-19-2018, 02:38 AM
I have only ever coded the instrument cluster, when fitting an engine with different cylinder configuration.
I believe the V6 and I4 instrument clusters are the same, but with different coding. The clusters can be coded for I4, V6 and V8. And fuel type can be coded for gasoline or derv.
EuroxS4
10-19-2018, 05:17 PM
I have only ever coded the instrument cluster, when fitting an engine with different cylinder configuration.
I believe the V6 and I4 instrument clusters are the same, but with different coding. The clusters can be coded for I4, V6 and V8. And fuel type can be coded for gasoline or derv.
Yes coding will get to show correct gauges.However miles to empty and so on need to be adjusted everytime different/bigger injectors are used.Normally adjusting krkte should be the correct solution.You can also play with KVB.But KRKTE is the right way.
augustmic
10-21-2018, 11:17 AM
Thank You.
I'm afraid I'll break the ECU.
I think that ColorMFA will be a simpler solution :)
shurur9
10-21-2018, 11:42 AM
My MPG appears to be off now that I have switched to an S4 cluster.
I read that filling the tank and resetting the MPG helps the ecu recalc the MPG.
dunno..going to try it.
MetalMan
10-22-2018, 02:35 PM
I agree with Nollywood. Did you re-code the instrument cluster? You adjust it from 6 cylinders to 4 cylinders as Nollywood mentioned.
The ECU fuel consumption constant should only be changed when fuel injectors (or base fuel pressure) are changed.
augustmic
10-23-2018, 12:54 AM
Yes, my instruments are changed to 4-cyl and RPM's are ok.
I have instruments from 3.0 V6 ASN.
I have motor: 1.8T BEX.
I changed injectors to BOSH 440cc.
eljay
10-23-2018, 06:06 AM
mine has been wrong ever since the 630cc injectors
Same here. I've maxed out the adjustment value with VCDS and I'm still off by about 1L/100km.
You will need to adjust in ecu software.So you will need to read out software from ecu and edit accordingly.I believe you need to edit map KVB or map KRKTE.Realistically if KRKTE is accurate no need to change KVB.
As I understand, KVB is adjusted to compensate for whatever the KRKTE (fuel rate) value is in order to display the MPG and/or whatever the metric equivalent is.
shurur9
10-23-2018, 04:27 PM
I agree with Nollywood. Did you re-code the instrument cluster? You adjust it from 6 cylinders to 4 cylinders as Nollywood mentioned.
The ECU fuel consumption constant should only be changed when fuel injectors (or base fuel pressure) are changed.
Q:
So where in VCDS is the cylinder recode done?
instruments 17-->???
I am not seeing it in the S4 cluster or on the VCDS site as something that can be recoded in the cluster.
B5 yes..but nothing for the B6..
EuroxS4
10-23-2018, 05:59 PM
I agree with Nollywood. Did you re-code the instrument cluster? You adjust it from 6 cylinders to 4 cylinders as Nollywood mentioned.
The ECU fuel consumption constant should only be changed when fuel injectors (or base fuel pressure) are changed.
It doesnt matter if cluster is recoded for 4 cylinder as he is using non stock injectors.Bigger injectors change krkte and so on.I believe stock 1.8T injectors were 186cc at 3bar,that value goes up as pressure goes up as well.There for stock krkte will not work.Need to recalculate.
shurur9
10-24-2018, 04:09 AM
I am just wondering where the suite is to change from 4-6-8 cylinders.
it was mentioned, but not said where in vcds it is found.
Human Garbage
10-27-2018, 09:14 AM
As I understand, KVB is adjusted to compensate for whatever the KRKTE (fuel rate) value is in order to display the MPG and/or whatever the metric equivalent is.
You are correct. I've adjusted mine to reflect the 386cc injectors installed. Of course KRKTE had to be adjusted as well, but that has no bearing on the cluster display.
EDIT: Here is the explaination from the S4Wiki:
Now that you have your fueling set up, you'll probably notice that your MPG readings in your cluster are totally wrong. Fill up a with a tank of gas, and reset your trip odometer and average MPG. When you are done with the tank, fill up your tank, see how much gas you used and how far you went, and check it against the new average MPG. Get a calculator out, and correct it here:
KVB - fuel consumption (MPG in cluster)
Standard KVB value can go only up to 776cc injector size due to reaching the maximum value it accepts.
To accommodate injectors larger than that you have to also change
FKVA - Constant conversion factor for consumption display
This is a multiplier for KVB.
For reference, you may be able to derive the right value using this (although some find trial and error tweaking is much easier)
https://wikimedia.org/api/rest_v1/media/math/render/svg/6c559766ae95318788125fac3e03282921cd4e11
SO WAGN
10-28-2018, 03:38 PM
Are you doing the tuning yourself with the ME7.5?
How is the car running currently? If your fuel trims are looking good then you must have TVUB (injector latency map) and KRKTE (injector scaling map) adjusted correctly for the 440cc injectors. If you're fuel trims are out (block 32 in VCDS) then I would start the process of dialing in the fueling correctly before looking at anything else.
I personally get TVUB dialed in first, you can use Bosch manufacturing specsheet to get the latency close but in my experience it is nowhere near close enough for smooth idle control. SMALL changes to KRKTE will allow for better understanding of what the car needs based on your fuel trims from Block 32 in VCDS.
Once you are satisfied that your close enough to 0% you can change KVB (constant for fuel consumption display in cm^3/min) to get the accuracy back in your displayed fuel consumption on the cluster.
If your car is running smoothly at idle and WOT you might already be at the point of just adjusting KVB but the information above might be useful to someone else in a similar situation.
EuroxS4
10-29-2018, 05:43 AM
Be careful when making changes.Everytime you make a change you need to make sure you correct the checksum otherwise you could end up with a ecu paperweight.
https://wikimedia.org/api/rest_v1/media/math/render/svg/6c559766ae95318788125fac3e03282921cd4e11
That equation is a good example of why I preface anything tuning related "as I understand" leaving a large margin for error on my part. [wrench]
SO WAGN
10-29-2018, 05:19 PM
Be careful when making changes.Everytime you make a change you need to make sure you correct the checksum otherwise you could end up with a ecu paperweight.
And back to the bench it is haha.
A fair call for the warning, I forget how cautious I've become since first starting out tuning. Use ME7sum to correct checksum's EVERY time a change is made to the .bin. It's quick, easy and free:
http://nefariousmotorsports.com/forum/index.php?topic=3347.0
That equation is a good example of why I preface anything tuning related "as I understand" leaving a large margin for error on my part. [wrench]
You're right, you'd think that if most functions are mathematical the subjective nature of tuning wouldn't exist. Yet, different tuners will utilise different tuning strategies and fight to the death that it is the "right" way. These ECU's are more complicated than women and as time goes on I can only hope that "as I understand it" leads to better performance from the tune.
The OP is only looking to sort the fuel consumption display, so I'm sure we can get you on the right path there.
I'm going to detail the process I would go through, you can decide if the fuel consumption being displayed is worth the effort involved to correct it.
***I take no responsibility for what anyone reading this chooses to do to their own car. If changing the tune and flashing your ECU is required, I would highly recommend flashing a spare ECU so you aren't left stranded.***
As you've mentioned, you will need more than VCDS in order to correctly scale the fuel consumption.
1. Use NefMoto ECU flasher to read your .bin file from the ECU. You may need to authenticate the ECU or defeat the immobilizer in order to read the ECU.. Topic for another day.
2. Use TunerPro to make adjustments outlined above (KVB and/or FKVA). You will need to find the correct .XDF definitions file for your ECU and software version.
3. Use ME7Sum to validate checksum. Use ME7Check as a final check.
4. Flash ECU with adjusted .bin file using NefMoto ECU flasher.
5. Drive car, check fuel consumption, repeat steps 1-4 if required.