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I seem to be the only muppet who had tuned his car to have just a good boost pull at partial throttle as full throttle , anybody else done it ?
Basically I was fed up of just getting actuator pressure or less at partial throttles and having to full throttle to get full boost , now it boosts to around 1 bar to 1.2 at partial or 3/4 throttle and then my target of 1.35 or there shouts at full throttle , car is so much more fun to drive now
Good to hear bud it makes sense , don't know why it's not more commonly done , granted it takes a bit of fine tuning but makes these cars a lot more pokey lol
Yes to the title question. No to the post question. Depending on the ECU, I tune to a target torque according to pedal position. The target torque is fulfilled by throttle opening first and then boost pressure only when necessary, ideally with a wide open wastegate as the default position.
This reduces pumping losses, exhaust gas temperatures (reducing the need for fuel dumping), charge temperatures, avoids compressor surge (although good ECUs have maps for that) and makes the car easier to control where the available torque is greater than the tyres can handle, or just simply for refinement.
If you have more grip than available torque and the engine is a low compression small capacity slug off boost and you want to make it feel lively with a cable throttle then your method can help if you do not surge and the bypass valve isn't leaking because of the pressure across the throttle.
Overall it is a fix for a problem most modern engines have fixed by means of some or all of drive by wire, torque management, variable valve timing and lift, electric wastegates and bypass valves, direct injection, high compression and short twin scroll manifold designs.
I too have tried to get good partial throttle boost. I found that setting the minimum boost duty helped a lot here. Still tweaking occasionally, but this is my current boost setup and seems to be working quite well:
EDIT: Looking at it a bit closer now though, I could probably increase the target boost in the mid-ranges a bit more, too. I'd be interested to see your setup @The Rig as mines just based mainly on me playing?
Last edited by ben.harris; 29 July 2017 at 07:52 PM.
I use my own designed motor adjustable 2 stage mechanical boost controller. Mbc try to give full boost all the time and it certainly does make the car pokey and great fun to drive!
So for sure it's worth trying to map in higher boost at part throttle, though I went mbc because it cuts out all the tuning needed and gives a very consistant boost curve with little to no spiking, well worth considering.
I agree this is a fix for the flat engine responce when off boost , to keep up with modern designed engines, ours are 20+ yrs old now lol
Im not familair with the later ESL minimum / maximum tables for boost so not totall clued up but looking at both of the posts above the duty is quite static, as you will see on mine i have to vary it keep a constant boost, sure the turbo dynamics are adjusting the duty cycles to lower than i have in my table, but if i then lower my table to what the ecu is adjusting it to i get a lower boost unless i really really stamp on the throttle at high revs.
anyhoo, my table with a 3 port, lowered the actuator preload quite a bit as i was getting 1 bar on acutator pressure alone from when i last fiddled with it
Ben , yes increase target boost earlier as you are pretty close to actuator pressure there
@Ben how come your 2nd two rpm columns in boost target are different to your duty tables? I think I remember you went on the ESL corse so wondering is this something which was suggested?
Does this not make it harder to adjust boost from your data logs?
@ossett2k2: Most of the adjustments that I've made have been on the Min/Max duty tables, not the Boost target table. I have to admit that I hadn't realised that I'd set them differently. I do seem to remember from the course, Andy said that most of the actual changes are seen from the Min/Max duty tables, and that the Target Boost doesn't actually achieve a great deal. I think it might just be used as a base for which Turbo Dynamics adjustments are used, although I don't know why I think that, so I could just be making an incorrect assumption!
@The Rig: Thanks - I'll give that try. I am aware that I can feel the turbo dynamics making adjustments quite often, so could probably do with some more varied, fine tuning on my duty cycles. I haven't really spent a great deal of time playing around with the mapping lately, what with house renovations and the arrival of our first child last week. Once things get settled down again though, I'll have a play! :-)
yes - target boost is used as part of the turbo dynamics, the target boost and actual boost figures create the boost error value which is then used as the axis for the turbo dynamics tables (so if your very far off target, larger corrections are applied). So it does have some bearing on things, as does the difference between the min/max tables (further apart will mean more turbo dynamics loops to get from one end to the other).
If you feel your turbo dynamics are making this a little flumpy you can always set the boost target to flat 1.5 bar across the board, you'll fudge the system so it runs more like the earlier cars that only have the max table. Personally I don't like leaving them like this as there is always a chance the car will actually make the higher boost value at some point in the future - but as a diagnostic effort you can use it to help set the max table up, then adjust the target value to be only a teeny bit higher than your actually seeing in the logs.
@Ben how come your 2nd two rpm columns in boost target are different to your duty tables? I think I remember you went on the ESL corse so wondering is this something which was suggested?
Does this not make it harder to adjust boost from your data logs?
Loads 61 and 80 have have the same duty cycles in there rows to the redline, whereas with mine they vary a bit to maintain that boost level, i have tried just putting say 65 in all the rows yet i get some vary poor readings lol, the turbo dynamics can only alter so much i guess, maybe cause im on the old setup and you have the minimum and maximum tables, altho the difference between your min and max is quite alot also but as long as it works
Did some fine tuning last night, im hitting 1 Bar at 3100 now and 1.4 at 3400 onwards to 5500 , a couple of dips where it lowers to say 1.35 or thereabouts but then picks up a 100 or so rpm later.
I am not technically minded so the above posting is way above me, but is the reason why these cars are only quick when you got full throttle?
It's one of the 1st things I noticed / found odd that my WRX seemed to have very little oomph at half throttle but when you planted the throttle it took off.
Bascially yes, granted most turbo cars only give full boost when you open the loud pedal fully , i hated this as i didnt always want to go full throttle hence changing duty cycles to suit me at partial throttle as i drive around the city most the time.
There are some other factors as well but i wont go technical lol
OK, so even though I said I wouldn't yet, I've had a bit of a play with the settings on mine. As you suggested @The Rig, I've increased the Target Boost table so that it's aiming for higher boost much sooner. I realise that most of the time it's unlikely to be able to generate the boost being requested, but I guess the theory is that it should keep the wastegate closed for longer to build the boost quicker. I'm really impressed with the result though - it's made the car feel much more lively, mid-throttle. I've also tweaked my Max Duty table slightly too, but I'm certain it's the Target Boost that's made the difference.
Something else that I did quite a while ago and seemed to help with spool, it to reverse the logic that everyone else seems to use for duty vs throttle position in areas where I'm not able to make full boost. My thinking was that when I'm not able to make full boost, I should be keeping the wastegate closed for as long as possible - i.e. duty cycle as high as possible, and then as the RPM's increase and the boost rises, that's when I need to start to reducing the duty cycle. You can see what I mean on the max duty table towards the upper left, where I have all the 90.6 values (the highest duty that seems possible from the logs) at the lower RPM values.
@The Rig: I know you've got the older ESL that doesn't have the Min/Max tables. I might be wrong on this, but I wonder if yours works on the principal that your "Boost Duty Map" is the same as the later "Max Boost Duty Map", and your "Minimum Solenoid Duty" would be the same as having exactly the same value in every cell of the "Min Boost Duty Map" on the later ESL.
Anyway - this is what my tables now look like, in case anyone cares!
EDIT: @ossett2k2 I've re-aligned the RPM's in my Target Boost / Duty Cycle tables as you suggested. Thanks for that - I hadn't noticed they were wrong.
Last edited by ben.harris; 03 August 2017 at 11:46 PM.
That's a big change Ben,just be careful,you will be making higher boost at lower down the load range or hitting a higher load at a lower rpm so I would think you've either added some fuel or pulled the timing/checked det?
That's a big change Ben,just be careful,you will be making higher boost at lower down the load range or hitting a higher load at a lower rpm so I would think you've either added some fuel or pulled the timing/checked det?
That's a good point - I haven't yet. I have been keeping an eye on my knock detection table though, and so far nothing logged at all, even after quite an extensive test on my way to work this morning. I think my fueling and timing maps are quite conservative, particularly in the areas which this change will affect, but it's a good point.
Tbh they don't look that conservative,not compared to mine but I suppose totally different car.
What is your timing advance table and knock threshold like?
Are you 100% sure knock detection is set up in the higher load areas?
Also notice your fuel and ignition load columns don't line up,not sure how much this matters but I just find it easier to read logs when both load columns are the same.
The map I posted earlier was the Total map. Here's the Advance map:
What do you mean when you say about checking which areas knock detection is set up for? Whereabouts do I do this? The only bit I've seen is the Knock Control Map, which (as far as I'm aware) is a read-only, in-memory table?
I think as default the knock threshold is 7 so unless you've changed it then it should be looking for knock in the areas you need.
You can set the threshold so for instance if it is set at 8 then anything bellow 8 in your ign advance won't be seen/adjusted in your knock control.
It can be used if your getting 'false' knock so you can switch off knock changes by lowering ign advance in any given cell.
I'm not 100% sure if it still logs a knock event tho even with it switched off?
I would be interested to know if it does(I've not tested that)
You set this in 'knock control' -- IAM ign Advance.
Mine is set at 6
Just to add,I'm not a pro mapper and still learning myself so take what I say with a pinch of salt lol
More experienced tunners will be able to explain better and hopefully correct me if I'm wrong.
Page27 in the manual.
Last edited by ossett2k2; 04 August 2017 at 10:01 AM.
Ah, OK. I've only ever monitored what my actual IAM value is (usually 16). I've never touched this particular table, so my IAM Ignition Advance is still set to 3, which was the setting in the OEM map.
So, by my understanding of reading this bit of the manual (again - I had read it previously, honest!), if any knock is detected anywhere where the value in my ignition advance map is greater than 3, it will reduce my IAM value down. So, for my map, knock found almost anywhere where I have ignition advance values will be treated as high load areas, so the IAM should be reduced if this happens. Does that sound right?
Ive had a bit of testing with the threshold and even if i set the threshold to 6 i still had correction (false) in areas where advance was only 5 so im not sure how or why the threshold actually works.
rememeber tho the knock control table is for closed loop only so above engine loads of 40+ it doesnt detect knock so its not gospol also even when it does detect knock its not gospol lol , i was getting false knock due to my gearbox .
its all good fun, detcans or knocklink are your friend , that crispy sound of bacon is the dreaded knock , cool when you actually hear it but not cool ha
even if my knock control table did have an alteration my IAM was still 16
I feel a trip to Screwfix coming on. Right - I'll stop hi-jacking your thread now and let it get back on topic. On that point though, tweaking the target boost table has made a noticeable improvement on my car, so thanks again for creating this topic! :-)
The way I read it is that any figure higher in the ign advance than the IAM threshold will be read as a 'high load' so I was thinking it will make adjustments anywhere(even high load) if the criteria is met?
I feel a trip to Screwfix coming on. Right - I'll stop hi-jacking your thread now and let it get back on topic. On that point though, tweaking the target boost table has made a noticeable improvement on my car, so thanks again for creating this topic! :-)
Dont be daft, going off topic is still on topic when it comes to self mapping
I found if i set my IAM threshold to 8 even tho i had cells in the advance table of 9 and 10 that were being hit, my IAM never increased above 12 and it took ages to change from the default of 8 and the car felt slow.
now my threshold is 5 my IAM changes to 16 virtually instantly i accelerate .
Defiantly nice to see more threads on DIY mapping,they are always very interesting and I learn more with every comment made
I've been doing some handling mods but will be back on the laptop soon map tweaking,I'm looking forward to fitting the 3 port bcs as i think it's well overdue on the turbo I'm running.
I'm not sure all of the tables it talks about are exposed by ESL. Purely guessing here, but I wonder if the threshold value we can change in ESL is actually used to determine the changeover point from fine correction (knock control table) to rough correction (IAM adjustment).
28 July 2017, 05:45 PM
Who maps their car for partial throttle ?
