Hi,

I wonder if someone can point in to a thread to help with tuning for a 4bar FPR?

I have a TT with a AET VT262C (rated 370bhp), DW65V, Bosch 117s + the necessary Intake, and Exhaust upgrades.

I have been tuning with the default settings from this forum
KRKTE  --
0.06205

TEMIN  -- 
0.7493

TVUB   -- 
7.96           10        11.97   14.01   15.98
2.6990   1.5389   1.1201   0.7308   0.5227

I have been managing to stay ahead of the ignition retard - and been adjusting the lamfa and timing whilst upping PID to come in line with the desired boost.  I made some changes which for the first time I have found myself where there is clearly too much boost and the fuel injectors cannot keep up - for example I have desired 0.82 but it is struggling to reach this and is 0.88 - this has only started happening since increasing the boost onset (this is quite a move before I was reaching 200 g/s at 5K and 240g/s at 6K  - but these changes are getting 200g/s at about 4K and 240g/s at 5K - this is now causing ignition retard on each cylinder.  I have fitted a 4 bar FPR instead but I am trying to find out what settings I need to change to utilise the 4 bar FPR - or is the correct solution to upgrade to 630cc injectors?

I can see that KRKTE is supposed to be lowered slightly - alternatively, is there any other changes I can do fuelling wise on a 3bar FPR - the "ms on time" for the injectors were 14ms to 18ms during this issue with keeping up with the desired.

at the moment I am keeping my logs to under 5K RPM when testing changes.

Many thanks for any pointers.

hardly a black art.

there really isn't anything special about 4 bar FPRs unless you're having fuel pump issues, especially if you have proper latency reference tables for whatever injectors you are using.

Hi,

Thanks for you replies,

The fuel pump is only a couple of months old and a genuine Dw65v - I hope it is not failing.

I think my issue is related to the PID alignment, I am going to return to a trusted bin which had very little ignition retard 1-4 and AFR Desired and AFR Current very close, but what I have seen when the Desired is not being met with the Current is the EffInjector is only for example 17.4ms at 4000RPM which is only about 58% injector duty cycle. (1/4000*60/1000 = 15ms * 2 = 30ms 100% IDC)  and then doesn't really get over 18ms up to 6K.

I am unsure about what the % of KRKTE is based on?   air mass percent?

for KRKTE from s4wiki it said to use 34.125 / injector size cc/min  (I originally put in 550 but I think these are actually 544 cc/min)  - but is the 34.125 specific to a S4 - as when I look at the VVVortex URL - it calculates it to a lower figure?

https://forums.vwvortex.com/showthread.php?5496661-Ongoing-DIY-Tuning-Bosch-ME7.5-for-1.8t

So I dont actually think I need to press on with the 4bar FPR until I am maxing out the 3bar FPR IDC's

tunerpro says that KRKTE is ms/%  and I had in 0.06205 in this and if I divide 17.4ms effinjector on time into 0.06205 it equals 280.42 so I dont understand is this related to load somehow?  my load was about 200, if this is related to the map sensor - I have gone over the limit and I wonder if this is the issue and I really need to drop the boost or the 5120 hack?  I thought there was a form of open loop in boost where the system used the Desired AFR and MAF to calculate the fuelling?

is the sensible thing at this stage simply get a 4bar MAP sensor and apply the 5120hack? 

I have seen someone elses 1.8T K04(stock - with stock injectors) log where they have 25ms effectiveinjector ontime on at 4K RPM so to achieve this the tuner had managed to handle over 18ms effectiveinjectorontime and would have been 25(ms) / 0.08347 (KRKTE) which is 300%, the load in the log was about 210 and the actual boost and desired boost were also at the map sensor limit. 

So I am wondering if there is a "max effective injector on time" somewhere set as 18ms?  I have put this into my ME7Logger config so will do a short run tomorrow with the reduced PID - aligned more with desired.

I am sure all these queries sound a bit stupid, but I am still trying to learn this - every time, I can see how something seems to be working in parallel with the s4wiki, some other input attribute interferes with my understanding

my actuator is too stiff so my WGDC range is limited in my current testing, but apart from easily going over the 22.5psi - I dont think that is causing the lack of IDC?  If the PID is the main culprit for this issue, once I have it aligned I will up the load to try and keep them aligned to see if the IDC increases/

Thanks for your patience and any pointers

I think you didn't understand how KRKTE, and If I can remember there is map for max injection time but it doesnt stop on 18mS,
And I have totaly wrong settings for MAF and injectors, but ECU was still trying to reach desired AFR. So as nyet said, solve one by one. Or you will get chougt in circle without exit

Sorry tiping from my mobile phone
Edit:
Take a look at this you will make things more clear about KRKTE
http://nefariousmotorsports.com/forum/index.php/topic,320.msg6774.html#msg6774

I would advise to not use TVUB to adjust idle, as it reflects physical properties of the injectors. As a matter of fact the values that go in this table should be given by Bosch. I would use FKKVS for idle.

Disagree. In fact, FKKVS should be fine as all ones unless the fuel system is returnless.

Incorrect TVUB results in idle fueling being off (offset affects low pulsewidth more than anywhere else), which is why adjusting it may be required, especially if you only have reference values for a different fuel pressure.

In any case, ALL maps reflect physical properties. If the theoretical values were correct, none of the maps would need tuning.

Disagree about what exactly? TVUB should be correct, of course idle will be off if it is wrong, never said or implied it should be wrong. When I say that it reflects physical properties I mean it is more like a description of the injectors' physical open delay based on voltage more than it is a setting to play with to adjust idle. I think it should be set to whatever the manufacturer is recommending and not be used for idle corrections only because it happens to take more effect on idle and sounds like the best choice. I had much better results adjusting FKKVS in low rpm/ms area with my idle and simply think it's the better choice.

Adjusting TVUB essentially tells the ECU what time the injector needs before it opens and starts letting fuel in. If you change it, yes it affects idle, but it just gives the ECU false data, which in my opinion is not the best solution to idle problems given there's a cleaner alternative.

This depends on entirely on two things

1) the source of the error
2) if you want to correct the source of the error in the "correct" map or you want to use the map that you are most comfortable editing and/or ends up with the best results.

FKKVS is the returnless fueling correction map. It can be used to correct for other things
KFLF and KFKHFM can also be used to correct fueling that isn't lambda req or MAF related.

If part/full throttle fueling is dead on correct but idle fueling is off, the most common reason is TVUB is calibrated incorrectly (most often due to aging injectors or non-stock FPRs which move latency around)

YMMV, can agree to disagree, there are a zillion ways to skin a cat.