Testament Posted September 1, 2017 Share Posted September 1, 2017 On 30/08/2017 at 23:02, Roman said: I would expect a more linear TPS vs MAP relationship when using a smaller throttle body. not really it has to do with the linearity of the valve type and its flow coefficient. a thin bladed butterfly is really not linear at all since the thin blade doesn't really obstruct flow very much until its about 1/3 closed and at the other end you get small changes in butterfly angle making massive changes in flow area. Going to a smaller valve will mean the first third will have a more immediate impact on the flow but the profile of that effect wont actually be linear. hence why OEM 90% of throttles have bell crank throttle pulls to get a mostly linear pedal effect matched to the throttle sizing and valve coefficient #imbeingpedantichere 5 Quote Link to comment Share on other sites More sharing options...
kws Posted September 1, 2017 Share Posted September 1, 2017 why do i have a thought at the back of my head that the Altezza TB is a weird semi-electric hybrid cable mechanical thing, not just a standard fly by wire throttle? Quote Link to comment Share on other sites More sharing options...
AllTorque Posted September 1, 2017 Share Posted September 1, 2017 /\ Dunno about the 3S Altezzas, but the 1G has a magnetic clutch between the throttle cable and the throttle plate so traction control can activate. Quote Link to comment Share on other sites More sharing options...
Roman Posted September 1, 2017 Share Posted September 1, 2017 4 hours ago, kws said: why do i have a thought at the back of my head that the Altezza TB is a weird semi-electric hybrid cable mechanical thing, not just a standard fly by wire throttle? That's exactly the case It has a cable from the pedal to the throttle body. If the e-throttle system has a fault, the cable can still pull the throttle about half way open so you can limp home. As mentioned there's an electromagnetic clutch that is between the e-throttle motor and the throttle mechanism, if this clutch disengages then the motor cant do anything and the throttle will snap shut. So it's an added safety feature. It's a good system having the cable there for redundancy, I had some teeth break off the gears in the e-throttle mechanism while I was down in Taupo and it was the cable operation that got me home. I have been thinking that perhaps it was the aggressive snapping open/shut that damaged the teeth. The e-clutch runs at 500hz but you can vary the pulsewidth with a table. So I found the minimum pulsewidth that could hold the throttle in place at 0% and 100% (22% DC) and then set it to this at the extremities so it would hopefully slip the clutch a little rather than shock loading the gears when it reaches the stoppers. But then sometimes this would cause problems at cranking when it's trying to adjust e-throttle angle to crank the motor, and give an e-throttle fault and shut the system down. So I made it a 3d table so it's got full 75% DC below 750rpm. 1 Quote Link to comment Share on other sites More sharing options...
Rookie Posted September 3, 2017 Share Posted September 3, 2017 Dave, you have basically confirmed the reason you tune itbs alpha n instead of map, good jerb. 1 Quote Link to comment Share on other sites More sharing options...
Roman Posted September 3, 2017 Share Posted September 3, 2017 Or MAF Quote Link to comment Share on other sites More sharing options...
chasinthemirage Posted September 4, 2017 Share Posted September 4, 2017 Sort of on topic, what fuel pressure regulators do people recommend? The OE one on my VL is damaged and I have SFA chance of finding another one. Not sure what's what and I don't want to risk damaging the engine running a dodgy aftermarket one. The motor is an RB30ET, all stock apart from the exhaust as far as I know. Quote Link to comment Share on other sites More sharing options...
Roman Posted September 5, 2017 Share Posted September 5, 2017 That's an impossible reccomendation to make, because you need to match whatever the factory fuel pressure is. And whether it's a rising rate regulator or whatever (I'm guessing it would be for turbo engine) I'd try find another standard one, or try find another nissan one that runs same pressure and is a compatible replacement. At the very least you're going to have to find out what pressure it runs at. Quote Link to comment Share on other sites More sharing options...
Yowzer Posted September 5, 2017 Share Posted September 5, 2017 Autodata says System preasure: 2.3-2.7 bar Regulated pressure with vacuum: 2.0 bar 1 Quote Link to comment Share on other sites More sharing options...
chasinthemirage Posted September 5, 2017 Share Posted September 5, 2017 From memory fuel pressure is about 40psi which would match what Autodata says. Will have to do some more research on it. My only previous experience with EFI is changing filters and hoses so I don't really know what I'm doing. Quote Link to comment Share on other sites More sharing options...
fletch Posted September 5, 2017 Share Posted September 5, 2017 It would appear the turbo and non turbo one is the same. I might have a n/a one on a motor in shed on my old mans farm. I can have a look in a few days if your keen. 1 Quote Link to comment Share on other sites More sharing options...
scooters Posted September 5, 2017 Share Posted September 5, 2017 be careful when your rooting around with regs. I'v been caught out before with boost referenced regs that are not your standard 1:1 rising rate. It stuffs everything up so bad and it takes a age to work out how things got so messed up. Fuel table with impossible non linear lines. Quote Link to comment Share on other sites More sharing options...
chasinthemirage Posted September 5, 2017 Share Posted September 5, 2017 @fletch that would be great thanks, I'll see if I can fix my one and let you know. @scooters that's what worries me, all this fandangled EFI is new ground for me. Quote Link to comment Share on other sites More sharing options...
scooters Posted September 5, 2017 Share Posted September 5, 2017 1 minute ago, chasinthemirage said: @fletch that would be great thanks, I'll see if I can fix my one and let you know. @scooters that's what worries me, all this fandangled EFI is new ground for me. You'l go ok mate. just go careful. There is nothing that is not online with calisturbo. PM me if you get stuck... VL was a lovely period of Fuel injection. 1 Quote Link to comment Share on other sites More sharing options...
Testament Posted September 7, 2017 Share Posted September 7, 2017 What are peoples thoughts on tuning for a stronger idle? specifically with only an on/off type idle valve one issue I have with the rather aggressive 6 puck solid centre clutch in the fiat its pretty easy to stall if you don't drive like a criminal 100% While some of that is just tough luck buddy rev it up and drop the clutch, it does seem like something could be done to improve it a little. like it occasionally (but not every time) dies when returning from free revving in neutral etc. when im pretty certain that a factory '80s injected car wouldn't and I don't see why I cant achieve at least that level of tune with the adjustability in the megasquirt/microsquirt. Can post up some of my maps/settings a bit later when Im home. Quote Link to comment Share on other sites More sharing options...
mjrstar Posted September 7, 2017 Share Posted September 7, 2017 I have had best results with feeding it more air (to bump the idle RPM up a few hundred RPM more than your desired idle RPM) and then a bunch less timing to settle the idle back where you want it, then outside of the idle zones crank the timing back in to it. this normally gives pretty sweet off idle response / stall resistance on the junk I work with. I have had to "re-do" a couple of mates cars then have come back from certain dyno tuning experts with crap off idle response and poor stall resistance. I have never bothered tuning idle to a specific AFR just to what "feels" strong (can even do the old carb trick of leaning out until revs rise then richen a bit). The return to idle stall can sometimes be attributed to injector over-run cut depending on wether you have this set-up, easiest way to check is to switch this off (or extend duration out to somethign silly like 30 seconds) and everything else should behave exactly the same. Keep in mind i don't have any science to back up these suggestions it just what has worked for me in the past, and the majority of stuff i deal with is turbocharged. 4 Quote Link to comment Share on other sites More sharing options...
Roman Posted September 7, 2017 Share Posted September 7, 2017 I've just recently been going through same thing, wanting to improve that first bit of power when coming off idle. Found same conclusion as per above, give it lots of air and then bring idle down with pulling timing. So then it gains timing back when it leaves the idle ign table and then its much easier to get off the line. 1 Quote Link to comment Share on other sites More sharing options...
ajg193 Posted September 7, 2017 Share Posted September 7, 2017 Also make it bump the timing up a bit when it drops below the set idle point, this should push the revs back a little. Unless your idle timing is already set to max power 1 Quote Link to comment Share on other sites More sharing options...
kpr Posted September 7, 2017 Share Posted September 7, 2017 that does work if you dont have any idle up, and want to keep the revs from dropping with electrical etc load. but if you ramp up the timing below idle too much it will just make it stall easier. depends on alot of things what afr it will idle nicely at. but aim for cruise afr numbers if it will do it, richer if not. then with load and below idle rpm try richen it up to 13afr or so. should help with stalling out. along with what roman and mjrstar said Quote Link to comment Share on other sites More sharing options...
yoeddynz Posted September 7, 2017 Author Share Posted September 7, 2017 20 hours ago, mjrstar said: "I have had best results with feeding it more air (to bump the idle RPM up a few hundred RPM more than your desired idle RPM) ....." Are you adding air with the idle air bleed screw or by using the idle control valve? I'm asking because I only use my idle control valve, a PWM unit, to control the warm up circuit. After its warmed up I have set my idle using just the fuel table and spark settings. I'm idling around 13 13.5 and pretty smooth at that, but I get that not so nice rich smell about the car. If I go much leaner, say to 13.5 - 14, then it starts hunting and going a little rough. And how much timing are you pulling? My engine is somewhere around 15 degrees at idle so there is room to pull some and still be close to what I think would be a 'factory' type idle tune? Edit; I must add that I'll never achieve a factory perfect idle, at low rpm, with an inherently unbalanced V6 running a super light flywheel. But its fun to try... Quote Link to comment Share on other sites More sharing options...
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