Reducing Boost/Load

[quickdraw]

Hi, - First. Merry Xmas all.

Running a K04 Turbo, CorkSport PS 68mm MAF / Intake, 3" Cobb DP (catted) , HPFP, CorkSport TMIC. I've recently installed VersaTuner and first started on the lower power tunes to familiarise myself. I have not tuned a car since the early 2000s and that was not Load Based. Done some MAF Calibration (seems stock MAF Cal is OK) and have now flashed the 93/98EU Octane Stage 2 CPE CAI + Corksport Race Pipe Tune but with the stock MAF Cal.

I've done a few pulls and logged them but I'm concerned that its overboosting for the K04 turbo and i'm seeing some Knock Retard.
I'm after some advice on what I should do and some queires to assist me to develop my tuning knowledge. I've attached a datalog.

- Low Absolute Load Values
The target load is around 2.3, but i'm only seeing 1.9-2.0 max. Is this the cause of the overboosting as its trying to make more load by increasing boost, but can't. What might be the reason I can't reach the desired load? The car is feeling very strong power wise. Torque limits are turned off.

Overboost Protection Fuel Cut

The fuel cut overboost is set to 254kpa, but on my WOT pulls i'm seeing 257kpa and did not feel any boost cut . Is the stock MAP sensor meant to be maxed out at 255? How can it be reading slightly higher?

Knock Retard

There is around 3-4 degrees of Knock retard at the end of the run. I do notice timing is being added. Should I pull 3 degress from the map?

Fueling

AFR's seem on the safe side, around 11:0. Should I adjust to aim for 11:5:1?

Any responses are much appreciated. Thanks

https://docs.google.com/spreadsheets/d/ ... ue&sd=true

Ryan

[mituc]

The OEM MAP sensor will max out at 257.8kPa but to be honest it's hard to tell if these readings are consistent with reality past like 252-254kPa.
To reach load 2.3 with a K04 turbo you will be around that MAP value by 3500rpm I think. However, before cutting fuel the ECU will try to lower boost by reducing wastegate duty first, then by lowering the throttle, and only after about 3 seconds in the overboost you will get a fuel cut (which is the last resort and not always the best situation to land on because of the mechanical shock, residual fuel which may still ignite, and so on).
The knock retard you are seeing is most likely not real knock (or not all of it), but ignition retard as a result of overboosting and also loss of traction judging by the desired AFRs.

So what you are trying to do is not feasible with your setup. Pushing a factory K04 towards where a CorkSport CST4/BNR S2 or an earlier version of a BNR S3 would live will not get you CST4/BNR S2/S3 power. The tiny exhaust housing and high wastegate duty will not accommodate that much exhaust flow, especially if you push the tune into the territory where it will run low timing (either because that's the tune or because the ECU pulls timing as a result of some limits being exceeded), because lower timing means more exhaust gas volume. So you're just torching the turbo and the exhaust side of the engine (valves, valve stem seals).

AFRs of 11 are safe, however once you figure out the boost/load line you can go up to like 11.7 by 4000rpm and tapper down to 11-11.2 by 6000. That's for a street tune. For a track/circuit racing tune I'd keep it like 0.2 AFR lower.

So what I'd do at this point:
1. lower the WGDG target value at least up to like 4500rpm, by at least 30% by 4000-4500rpm. Hitting 100% WGDC at 3800rpm will not give you the maximum flow from that turbo at that RPM;
2. make sure the overboost throttle reduction table has values with at least 3-4kPa less than the fuelcut overboost table. Go with like 250Kpa for throttle reduction and 254-255 for fuel cut. This way the ECU will have some time to adjust the WGDG and throttle before pulling a ton of timing and torching the turbo even more;
3. set realistic load targets and then work your way up from there. Now you saw that with your setup and in that weather values of load 2 at around 4000rpm will already throw you past what the factory MAP sensor will read. You may (and should) be able to exceed load 2 with your setup but only after you manage to properly adjust the tune... now it's a bit of chaos in there;
4. low timing means more exhaust heat AND volume. This will reduce the ability of the engine to produce power because it's overwhelmed on the exhaust side. The factory tune already runs timing values for like 87 octane fuel, if you lower it even more you will not get anywhere.
5. how is your VVT table looking like? You might post the tune as well to see what changes you made and discuss on how each of these changes affects the power.

[quickdraw]

Thanks for such a detailed response. I'm using a stock versatune map with only change being the stock maf calibration. That's why I'm surprised it's setup for 2.3 load but doesn't mention a bigger turbo is required. The tune is the one called 93/98EU Octane Stage 2 CPE CAI + Corksport Race Pipe Tune. I've made no other changes to it.

[mituc]

That particular tune is pretty extreme in demands and the turbo needs to be in tip-top shape to meet those targets.
Also, in your log I think there was quite a bit of wheel spin, maybe if you can do a pull in a higher gear and you will not have as much wheel spin (which means a lot of timing being pulled) things will look a bit different.
Also, please use this logging preset for logging: https://www.dropbox.com/scl/fi/s7e5zpu3 ... gug12&dl=0
Download the file, open in in your versatuner from Dashboard -> presets -> import and then load. Let's see a bit more params and a higher gear, I believe your previous log was in 2nd, so use at least 3rd, or if it was in 3rd then use 4th.

[quickdraw]

Ok cheers. I'll lower the load targets closer to the previous ots tune . Yes that run would be 2nd gear.

Thanks
I'm sure I'll have more question later as I dive deeper into self tuning.

[mituc]

Ok cheers. I'll lower the load targets closer to the previous ots tune . Yes that run would be 2nd gear.

Before changing the tune take a 3rd gear log. With less wheel spin and proper timing things may look a bit differently. Not by much but certainly better.

[quickdraw]

Mituc, i've done a 3rd gear log to 5500 rpm on a cool night so I didn't hit any boost cuts. Log attached.

Few things I've noticed that i'm curious about.

The desired AFR is much richer than the actual. Do I need to work on my MAF Table? Though I have a stock size MAF housing so it should be as per stock table.

Load hits almost 2.2 in the low end, but then decreases from there even with the same boost pressure. Am I just too rich here which is reducing torque?

Accelerator Pedal Position maxes at 66%. Is the table APP Request Load Normal limiting load values as anything over 66% isn't being touched?

Any help will be much appreciated.

[quickdraw]

In addition I've noticed at cruising closed loop conditions the commanded and measured afrs are 14.3.1 . Any idea why this is not 14.7? The afr tables are all set to 1.0lambda at these loads.

Thanks

[mituc]

Mituc, i've done a 3rd gear log to 5500 rpm on a cool night so I didn't hit any boost cuts. Log attached.

It did actually, but it did not stay there long enough for the ECU to cut fuel or even close the throttle by a significant amount (only like 3-4%). Between lines 1002 and 1010 the boost is the maximum a factory MAP sensor can read.

The desired AFR is much richer than the actual. Do I need to work on my MAF Table? Though I have a stock size MAF housing so it should be as per stock table.

I agree, but on the other hand the factory MAF calibration was made for pump gas back in early/mid 2000's when not even E5 was on the market, while these days we have E10. The 6-8-10% ethanol content really has an impact on the actual AFR, therefore ideally (but not necessarily) the MAF calibration should be re-done. Even so, the tune adapts pretty well, in your log during that WOT pull the desired versus actual AFR is around 3-4% towards the lean side, which is not a problem at all.

Load hits almost 2.2 in the low end, but then decreases from there even with the same boost pressure. Am I just too rich here which is reducing torque?

You're just above the fuel cut boost limit when you hit load 2.2, and around 4800-5000rpm you're also out of turbo.

Accelerator Pedal Position maxes at 66%. Is the table APP Request Load Normal limiting load values as anything over 66% isn't being touched?

This is what we usually see on gen2 CX7 and gen2 speed3/BL 3MPS.

In addition I've noticed at cruising closed loop conditions the commanded and measured afrs are 14.3.1 . Any idea why this is not 14.7? The afr tables are all set to 1.0lambda at these loads.

It's hard to tell because you are not logging the engine coolant temperature. I posted a link above with a logging preset that contains all the parameters you need to understand what's going on with the car... you should use that.
Also, regardless of what you did with the car in that log, the boosted air temperature was 35-39C. This is not really possible, it should vary a lot more, especially during the WOT run and then after. What MAP sensor are you running? If it's the factory one maybe it needs a bit of cleaning...

[quickdraw]

Really appreciate you taking the time to respond Mituc. I've added some comments below.

It did actually, but it did not stay there long enough for the ECU to cut fuel or even close the throttle by a significant amount (only like 3-4%). Between lines 1002 and 1010 the boost is the maximum a factory MAP sensor can read.

As yes, what I meant was a fuel cut. But I did notice that small spike.

I agree, but on the other hand the factory MAF calibration was made for pump gas back in early/mid 2000's when not even E5 was on the market, while these days we have E10. The 6-8-10% ethanol content really has an impact on the actual AFR, therefore ideally (but not necessarily) the MAF calibration should be re-done. Even so, the tune adapts pretty well, in your log during that WOT pull the desired versus actual AFR is around 3-4% towards the lean side, which is not a problem at all.

Thanks, i'll work on the MAF calibration in the higher load areas / open loop. Note the pump 98 fuel we have here in Australia is ethanol free

You're just above the fuel cut boost limit when you hit load 2.2, and around 4800-5000rpm you're also out of turbo

.
So what I understand now, is it hits the boost limit and starts reducing the duty cycle (though I thought it should be also closing the throttle at 248kpa but i'm not seeing that) , which drops the load. Once the boost is below the limit it trys to catch back up creating a hole in the tune before the turbo runs out of puff where its at 100% wdc and no longer at the boost limit but neither reaching the target load.

So (correct me if i'm wrong) I believe i'll need to lower the target loads to slightly below 2.2 to remove that overboost event and I should see a more consistent load value up until the turbo runs out.

It's hard to tell because you are not logging the engine coolant temperature. I posted a link above with a logging preset that contains all the parameters you need to understand what's going on with the car... you should use that.

Sorry yes I actually removed coolant temp on that run to free up a parameter to log as it was pretty much consistent around 80 degrees C.

Also, regardless of what you did with the car in that log, the boosted air temperature was 35-39C. This is not really possible, it should vary a lot more, especially during the WOT run and then after. What MAP sensor are you running? If it's the factory one maybe it needs a bit of cleaning...

Interesting observation. I've looked back over all my other logs and I see the same. I just thought the intercooler is doing its job well. I'm assuming it has the stock sensors, but i'll look into it.