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Davidv

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Davidv last won the day on August 20

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  1. Davidv

    rough idle help

    If youve got aftermarket cams you might be getting some overlap which makes your map signal unstable at idle. You could make a second fuel table that uses a virtual aux as a switch, so switches to an idle fuel map that's TPS based when you're below say 2% throttle and 1500rpm.
  2. Davidv

    E-throttle for 1JZ in RX8

    So long as the RX8 outputs two APS signals from the pedal then it will work fine that way. ECU just wants 2 TPS and 2 APS, doesnt care where they come from. Yeah you can setup a table to vary the e-throttle angle based on cold start etc so no ISCV needed. Just something to note, make sure your normal throttle map keeps the throttle plate away from the end stops, like if right to end stop is 100% travel then only go 98% or whatever. As otherwise you break e-throttle gears if it slams the stops (been there done that) If that e-throttle setup has an electromagnetic clutch like the Altezza system does, then you can run a PWM to it to soften the clutch near the end stops to reduce chances of damage.
  3. Davidv

    V88 3SGE VVTi LCA table

    No you can only physically advance the pulley that far, everything is working correctly.
  4. Davidv

    Idle setting for open loop and closed lopp

    ISCV is too slow to really be useful for quick changes in closed loop, you really need to get your fuel dialled in nicely and then ignition trim is the best way to keep it stable in my opinion.
  5. Davidv

    VVTi - link to TP% or MAP?

    Okay so here is why I switched back to a MAF from a MAP based setup. When you are at part throttle and have cam overlap, the low pressure in the intake manifold pulls some exhaust gas back into the cylinder and intake manifold. The more advance you have at lower load, the more this happens. It's good for economy, but unfortunately when intake manifold pressure is the load axis it throws things out of whack. Because you are measuring the pressure with the assumption that all of the air in there is fresh air giving you a certain amount of pressure. When you have some internal EGR happening, for a given MAP reading you want less fuel and more ignition timing, but the ECU sees a higher map reading so puts in more fuel and then less timing. When you use a MAF as a load axis, it only ever reads fresh air coming in, rather than making assumptions about the composition of the gas inside the manifold, so its always way closer to correct. As well as the multitude of other accuracy benefits that a MAF has. This is on a single VVTI beams 3SGE engine.
  6. Davidv

    VVTi - link to TP% or MAP?

    I've been in two minds about this, currently with a MAF based tune on my engine (NA Toyota) I've got TPS as the load axis for VVTI. But I think with a MAP based tune it makes more sense to have it on same load axis as your fuel, because unlike MAF, MAP has no way to tell how the VE of the engine changes with cam angle. But the catch 22 here is that changing the cam angle can change the map reading at part throttle so it's a bit of a circular reference. Realistically I doubt you'll have much trouble using either.
  7. Hi, Currently with mixture map you set a threshold so that samples within say 25% of the centre of a cell vertically and horizontally. This pool of results are used to contribute towards an average value in the centre of the closest cell. However this means that you've got 25% variation of rpm and load, contributing to a static value in the centre - and you need to throw away 75% (?) of recorded values. I have another idea that can let you use all of the data instead, and improve the results. For simplicity's sake imagine a 4x4 grid, and our current load and rpm point is 25% of the way towards the lower RPM value and 25% of the way towards the lower Load value. If we interpolate these values, as per what the ECU does. Note: I have just titled the columns and rows with percentages to show what percentage of the each cell we are interpolating from. We get a value of (25% * 25* 10) + ( 25% * 75% * 30) + (25% * 75% * 20) + (75% * 75 * 40) = 0.625 + 6.075 + 3.75 + 22.5 = 32.95 is the table value that interpolation produces. Now lets say that you wanted to add 10% to this value. If we just adjust the closest cell by 10%, as per current Mixture Map strategy. Then our bottom left cell changes to 44 so our table now looks like this: If we do the interpolation again, but with the new value to represent running the car again after the update: We get a value of (25% * 25* 10) + ( 25% * 75% * 30) + (25% * 75% * 20) + (75% * 75 * 44) = 0.625 + 6.075 + 3.75 + 24.75 = 35.2 as the new overall value. Which is only makes 6.8% difference to the interpolated value, rather than the 10% we wanted. On the other hand... If PCLink De-interpolated the 10% that it wants to add. Instead of adding 10% to the one cell, we split the 10% addition across the 4 cells based on the same percentage that the value was interpolated from initially. So: Top left cell: (10 * 1.1 * .25 * .25) = 0.6875 Bottom left cell: (30 * 1.1 * .25 * .75) = 6.1875 Top Right Cell: (20 * 1.1 * .25 * .75) = 4.125 Bottom Right Cell: (40 * 1.1 * .75 * .75) = 24.75 = 35.75 is the table value that de-interpolation produces. We were trying to add 10% and this new value produced is 10.5%. So that's pretty good! (The 0.5% error comes from rounding to 3 decimal places in my example) So it's accurate to the provided data in every instance. Which is especially relevant when it's applied 1000s of times across all of the cells. You dont need to throw away any of your recorded data, it all contributes to the cell values. Mixture map is pretty good for roughing out a map initially but because of the inaccuracies of the "nearest cell" method I don't really use it that much anymore when trying to dial in a fuel map. You always overshoot or undershoot unless you set your cell tolerances impossibly tight and have millions of samples. And, since this is all only done in PCLINK rather than the ECU, there's not really any worry about the overheads of the extra maths involved. It's worth having it chug away for a few minutes longer if you can get an awesome result on first or second iteration of Mixture map logging. So - that's my Friday night suggestion. Thanks for reading if you got this far, haha.
  8. Davidv

    Laggy PCLink software

    Just been having this same issue. I have been using a disgustingly slow netbook for ages, Win7 with Pclink running awesome. Shiny new Win10 laptop and its as good as unusable. Just onboard Intel graphics card. Will see if there's an older driver.
  9. Davidv

    E85 and cold corrections

    Yep that was my original theory too which is what instigated the testing with myself and Mike. I could end up pulling out a massive amount of fuel in idle conditions and car ran quieter and smoother. And that was just with petrol then Mike tested with E85 to good results as well. I'd like to have a play with E85 but my fuel system would shit a brick haha. Ive found this works awesomely to make my car quieter and a lot nicer when cold as well, but not sure how well it translates to a map based setup (that load axis only available with maf) There's no science to the numbers though was just a first guess to see how it pans out, and was an improvement.
  10. Davidv

    E85 and cold corrections

    I have found some extra ign timing when cold helps too. Overlay ign table with ect and load as axes. Thats with petrol only but would assume similar for e85. Notice any difference with that for you, Mike?
  11. Thats awesome! Is the head reversed on that? Am I right in thinking its a gen 3 3SGE based engine. Pity it's not a beams or you could use my same roller setup. And re: fuel pooling, a friend said that when he tried it (with inboard injectors only) you'd just get fuel vapour/mist partially sucked into that inner part of the barrel because it holds a partial vacuum. Then it's got nowhere to go because of the barrel angle. So then when you go WOT it all dumps into the intake. Not sure how much of an issue it really is though.
  12. Oh my - Your brother has a BTCC car? Details please! And yes that 4AGE / starlet is the business! Also, with regard to linearity of throttle actuation. I ran this through the flow bench calculator thingy at different throttle opening angles, to measure the restriction in 5 degree iterations. Doesnt look nearly as bad as I thought, but this is hoofing an absolutely tremendous amount of air through a runner in steady state. But I'm thinking part of the reason people talk about drivability issues at part throttle could be on account of the roller barrel being so close to the head, and negatively impacting air/fuel mixing & airspeed. It's also possible that when the airflow demand is much smaller it will reach peak required amount of airflow at a very low throttle angle. Something else that I've noticed about the Titan rollers, they actually have a trimmed out part on the front face of the roller, so the inside of the barrel doesnt fill with partial vacuum. At idle conditions there's a 6mm gap between the front roller edge and the housing, while the back is shut. That probably solves the fuel pooling issues and weird issues that arise from having two "cut off points" in the flow path at low throttle angles.
  13. Hi, I have been giving some thought to making some Roller Barrel throttle bodies. So firstly if you havent seen them, the idea is that they are a rotating tube (barrel) with a hole in it. Rather than a butterfly valve which always has something in the flow path, even at full throttle. There are only a few cars that run these, or have run these - For a few good reasons. But the BTCC Vauxhall 2 litre engine ran these with a cool looking set. And made somewhere in the order of 320hp NA: https://racecarsdirect.com/Advert/Details/82002/swindon-rollerbarrel-throttle-body-kit-vauxha One of the Caterhams runs roller barrel throttles from factory, with a set made by Titan/Cosworth. Apart from that, and a few references to them previously being used in F1 cars at some point, there seems to be very little information about them. So the benefits: 1. Gimmick factor 2. Low restriction 3. Can keep the entire intake length, the same profile as the port easily. Rather than needing to go to a round shape to suit a throttle plate 4. Very compact 5. Very easy to fabricate compared to butterflies 6. Apparently generates very little vacuum at part throttle The downsides: 1. They have a tendency to jam 2. Not very resilient to fuel sludge residue or small particles coming into the barrel / housing clearance. 3. Apparently the opening rate is very very very non linear. Like, quarter throttle feels like full throttle. 4. Apparently generates very little vacuum at part throttle (Yes this is a benefit and a downside) 5. If the roller is very close to the head you can have poor quality of airflow/airspeed and so poor air/fuel mixing. 6. The inner part of the barrel pulls some amount of vaccum, and you can have fuel pooling issues inside the barrel with extended periods of part throttle. So here's why I'm going to make some anyway even though they are pretty much unreliable garbage: 1. Gimmick factor 2. They are very light 3. Learn how to make something new 4. I can use e-throttle to overcome the traditional disadvantage of a non linear opening rate 5. Gimmick factor 6. Possibly slightly higher horsepower potential 7. Gimmick factor So the first thing was to draw up a model. Pretty blatantly copying the Vauxhal and Cosworth design here. Two cylinders per barrel. But with dimensions to suit the ports of my engine. No point in reinventing the wheel. (Well, lets ignore the fact that roller barrels are shitty so I'm essentially reinventing a triangle shaped wheel) Then made some molds for the trumpets, for making some molds for the trumpets, to make the trumpets. Without the return edge on the bellmouths for starters while I try figure out how to make molds and use carbon fiber and so on. Gotta love 3D printing. Then after about 500 iterations and failures, making one that turned out alright. Not quite there but learning something from each iteration. Nearly good enough! I might add some draft angle / taper to the length of it and mmaaaayyybbeeee think about the allowance of a secondary fuel rail at some point. Seeing how I've got enough injector drivers and so on for staged injection with the Xtreme. I've 3D printed a test pair of the throttles, that I've test fitted to a dummy engine. But need to pull my car's actual intake off at some point and test for clearance to see how long the trumpets can be. I'm anticipating that they will need a curve in them for bonnet clearance, for the length I'd want. But that's not an issue. From here I need to finalise a few bits such as, decide what sort of bearings to use to support the rollers. Decide how to fit return springs to the roller assemblies. Decide how to balance the two halves together. Decide how to actuate the throttle, either cable pull for starters or e-throttle. The outer housings themselves though, and the flange to the engine are as good as finalized though. So just need to find a few chunks of alloy and start machining! Or possibly get the housings cast instead. I am anticipating that MAP readings will be next to useless. So it will likely be Alpha N based tune, or depending on how the airbox and intake arrangement works out. Possibly MAF based so long as the pipe isnt too big. Thinking that 4" pipe might be about the limit before you dont get much resolution from a MAF. But could perhaps use an Alpha N / MAF cross over. Will see how it goes. First thing is to start/finish making them haha. Dont hold your breath for updates this is going to take me a few months of mucking around to get sorted from here. But a brain dump of what I've been doing so far will help keep me motivated! And some peer pressure haha.
  14. Davidv

    e-throttle opinions - worth it?

    Yeah mine is really snappy. If you look at the logs of requested throttle angle vs actual, it's very fast. Not instantaneous obviously but its not half a second delay or whatever that OEMs feel like. In my opinion the OEM mushy pedal is likely for sake of reducing the amount of harsh transient conditions where fuel is least best controlled. For emission / economy reasons.
  15. Davidv

    e-throttle opinions - worth it?

    E-throttle is just awesomely awesomely awesome. Firstly - Cruise control Secondly - Much easier to set a non linear opening rate to give you more control over the engine thirdly - Context sensitive pedal control. Make the pedal less sensitive when it's raining, or give the engine less total throttle opening at low rpm, or whatever you need to do to make the car the most drivable in those conditions. Heard a really good example about a guy who raced in a series with a breakout laptime. He would tune the max throttle opening down, so that he would drive full throttle each lap and stay just over that time. But then if he was in traffic he could switch it off, zing past someone then resume the previous throttle mode. In my opinion (for combined road/track car that I use) even just having the cruise control makes it worth while. EDIT: Using a G4+ though so I'm not sure which of the above things are available on G4.
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