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#255
by
vanbcguy
on 13 May, 2014 01:53
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Still tuning...
Playing with a different version of the VNT software, this one does PID control. Found a bug this evening that explains the overshoot I've been seeing. I've taken about 30 logs now - the "aha!" light bulb came on tonight looking at a log after some code changes. I can finally see why things weren't reacting the way they should. Not sure when I'll get a chance to fix things, hoping tomorrow but I might not get any car time till Thursday.
Also spent some time and designed a PCB rather than the prototype board. I've been having some analog noise issues that I realize need some extra filtering. The current board was good to get started but there is basically no room for the filtering caps and things I need. The PCB will obviously be a better final solution too. Got a great deal - 3 boards made for $30. The BOM component wise is about another $50 but $35 of that is the two pressure sensors. Doing without the EMP gauge would save about $15 but then again you can't get an EMP gauge for that little!
Sent from my HTC One XL using Tapatalk
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#256
by
vanbcguy
on 14 May, 2014 12:27
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Oooh... MUCH progress...
Will be running on the prototype board till probably the end of the month but I am starting to get something approaching usable logs. I've got good control at steady states with lower boost levels now. I need to do more PID tuning but my PID loop is actually working properly. Sweet.
For anyone who might be interested, here's the current version of the code I'm using plus the board design (which includes schematics that can be loaded in Eagle):
https://github.com/vanbcguy/vntldaThe uploaded code version has had a day's worth of fiddling without being loaded in to the car yet, and the board is out for production but hasn't been built yet. YMMV etc...
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#257
by
rbremiller
on 14 May, 2014 18:43
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The conversion circuit I used I found on a Megasquirt forum. It outputs a pulsed +5V signal.
This is the page I found:
http://www.aaroncake.net/rx-7/megasquirt/buildingandmodding.asp
Look for the section titled "2nd VR Conditioner Circuit" - it uses a chip designed for exactly this purpose. I was able to get everything from Digikey for about $12.
Thanks for the great info. Did you put this circuit on a separate project/prototype board or is in incorporated with your main board? Do I need to shield the signal from the sensor to the dash/cluster? I may be asking a lot but do you have a parts list from your Digikey order? I'm good with soldering(I replaced the transformers in a flat screen TV recently) but in-depth knowledge of component specs/calculations is outside my comfort zone right now.
Rich
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#258
by
vanbcguy
on 14 May, 2014 18:58
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The conversion circuit I used I found on a Megasquirt forum. It outputs a pulsed +5V signal.
This is the page I found:
http://www.aaroncake.net/rx-7/megasquirt/buildingandmodding.asp
Look for the section titled "2nd VR Conditioner Circuit" - it uses a chip designed for exactly this purpose. I was able to get everything from Digikey for about $12.
Thanks for the great info. Did you put this circuit on a separate project/prototype board or is in incorporated with your main board? Do I need to shield the signal from the sensor to the dash/cluster? I may be asking a lot but do you have a parts list from your Digikey order? I'm good with soldering(I replaced the transformers in a flat screen TV recently) but in-depth knowledge of component specs/calculations is outside my comfort zone right now.
Rich
If you download Eagle (it's free) you can load in my schematic for my full project from the GitHub link 2 posts up. It has the full schematic, all parts and their values, etc.
I've got the circuit built right in to my board - figured if it were good enough for VW that way it'd be good enough for me. Shielding wise the PWM stuff for the solenoids would be the main thing I'd be concerned about - it's around a 60Hz signal with my code. Solenoids are nasty - when you interrupt power to them they throw back a big spike that can be 2-3x what the feed voltage was, I do have diodes to soak that up but I should have installed them right at the coils themselves rather than on my board. The new board design still has the diodes on the board but they are far away from the other signals as much as possible. My prototype board doesn't have any filtering capacitors whatsoever on it and I've had some issues with noise on my TPS signal (though strangely only when it is hot, which makes me suspect the TPS itself - either that or it is somehow picking up interference from my engine cooling fan) Anyhow the PCBs that I've ordered have all the filtering caps that should be there, especially on the input voltage regulator, the +5V output from the arduino and on the various sensor signals themselves.
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#259
by
vanbcguy
on 14 May, 2014 19:07
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OK some good and some bad...
Tuning wise I'm rapidly closing in on a good tune. I'm getting decent boost regulation now - a little overshoot but not much hunting any more. I fixed my code so I can actually set min duty cycle values on the map now - that will help as I can narrow down the range that the PID loop is working with - especially now that I have a pretty good idea of what the "normal" duty cycle values are for cruising along, etc. I set a minimum of 15% when not idling this afternoon which made a HUGE improvement, I think I can probably raise that closer to 25-30%.
I may also set a lower maximum right around spool RPM - what is happening right now is the PID algorithm is trying to get the boost up below 2K RPM when the turbo hasn't spooled yet. It cranks the duty cycle up progressively higher and higher till the turbo finally DOES spool and WHAM, suddenly I've got 20PSI when I was shooting for 10. If I cap the max duty cycle right around 2000 RPM at lower TPS values that should help with that particular phenomenon.
Wow, ain't this fun? Gone crosseyed yet?
OK, and the 'not so good'...
When I got my first batch of parts I ordered a bunch of stuff from ECS Tuning. I didn't realize at the time how crappy they were for shipping to Canada (got a massive customs bill due to the type of shipping service they used). I also didn't realize how bad some of their parts were. I got my serpentine belt tensioner pulley and my water pump from them. The belt tensioner pulley stupidly has a casing mark right around the middle of it which is leaving an impression in my belt. But more serious, the water pump I got from them sounds like the bearing has crapped out already - it lasted 600km. The brand was 'URO' which I've since found out is absolute crap.
I've got a new water pump and serpentine belt pulley coming now. Pulley is INA, water pump is Geba. Not particularly happy about having to yank everything apart to do the water pump but to be honest I should have sent it back right when I got it - it came with some of the bolts not fully installed and the metal it's made out of mars up if you even look at it funny. Bah. Wasted time, wasted money.
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#260
by
sdubfid
on 14 May, 2014 21:03
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Any reason you don't deal with vm autohaus near BCIT?
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#261
by
vanbcguy
on 14 May, 2014 22:50
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Actually a huge chunk of my car is from them... :-) Lots and lots of the little stuff that you can't do without. ;-)
Sent from my HTC One XL using Tapatalk
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#262
by
bbob203
on 15 May, 2014 10:46
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I saw an old friend the other day that works for ecs he said stay away. if not crappy parts they just have horrible bussiness practices.
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#263
by
vanbcguy
on 15 May, 2014 19:45
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I saw an old friend the other day that works for ecs he said stay away. if not crappy parts they just have horrible bussiness practices.
In my case I got some poor quality parts but that was more my problem than anyone else's. I also got a really awesome Peloquin LSD from them and some awesome ARP head studs - no issues with any of those products. My own fault for not checking better on the brands of the various products.
So I noticed quite a bit of black plastic dust around my tensioner pulley today. The new pulley and water pump had shown up so I figured I'd change the pulley first since it's a 2 tool / 10 minute job.
The tensioner I had gotten from ECS had a plastic ring covering the bearing between the pulley and the arm that had come loose. Lots of evidence of it rubbing around in there. I'm pretty darn sure that's what my noise was now. At least it was an easy fix! It was only ever really loud when the engine was cold so I won't know for sure till tomorrow, but everything sounded fine when I started it up after changing the pulley out.
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#264
by
vanbcguy
on 16 May, 2014 16:14
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Fargh, it wasn't the tensioner (or rather wasn't "just" the tensioner). The noise is getting worse fast, so I guess I'm doing my water pump some time in the next few days.
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#265
by
vanbcguy
on 20 May, 2014 10:54
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I've been working away at my tune. I've got peak boost up to around 1.75 bar now (graph is in kPa). I still have a bit of an overshoot that I'm working on calming down but at present it just in the safe range of the turbo, I will just need to get it under control before I crank the boost up any further. Takes a few iterations for sure!
Boost/Target are in kPa, duty cycle/tps is in 8-bit so divide the number by 255 to get percentage - ie 150/255 = 59% Generally speaking anything over 60% duty cycle makes boost nearly instantly but you can really feel how much it chokes up the engine. I haven't hooked up my EMP sensor yet. It's also hard to back off fast enough at higher duty cycles so as not to overshoot. I've got a target boost map, a minDC map and a maxDC map - the PID control loop is allowed to go anywhere between minDC and maxDC, so for overshoots I need to reduce maxDC, to improve responsiveness I increase minDC.
Peak EGTs hit 600C (about 1100F) on that run. I haven't included my LDA solenoid duty cycle in the logging output yet but I suspect it was just starting to hide boost from the LDA on that pull - my EGT map hits a 50% duty cycle for hiding boost from the LDA at 650C (~1200F) and has the LDA fully disengaged at 720C (~1400F). I've still got room for more fuel at this boost level and I've still got more boost capabilities from this turbo (it is 'safe' to run it at about 2.15 bar)
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#266
by
vanbcguy
on 21 May, 2014 02:29
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Replaced the crappy URO water pump I had on the car with a good quality one. The URO pump was definitely bad - there was noticeable play in the shaft already plus there was dried coolant residue below the weep hole. I had been leaking some coolant earlier on but the leak more or less stopped, I guess I know where it was coming from!
UNFORTUNATELY I still have a nasty rattle sound to deal with though. Kind of annoyed - I've replaced two defective parts now (that really were defective) but I haven't gotten the actual problem I'm chasing. I'm now suspecting my alternator - it is a new Bosch Premium reman. I guess I could swap in the original AHU one to see if the noise changes. If it's not the alternator then I'm sort of stumped, but I did notice today that the sound seems to follow the alternator's over run - ie if I rev the engine to 4K and then drop to idle the sound keeps going for a moment while the alternator slows down.
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#267
by
vanbcguy
on 21 May, 2014 19:37
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Well what the hell. I spent some time with the engine running with the car on ramps. My noise definitely was not coming from the alternator, it was coming from somewhere around the bottom of the engine.
Checked the PS belt - it was a little loose so I tightened it up. No change really. Went for a short drive, the squealing noise got worse. It was making a squeaky squeal even at idle. Started thinking about what this could possibly be....
Wait, I reused the old harmonic balancer. Hmmmmmm...
Marked the inner and outer parts of the balancer, started the engine. Ran it for 30 seconds and shut down. My marks are a quarter turn away from each other! Yep, found my noise.
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#268
by
vanbcguy
on 28 May, 2014 09:33
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Took her for a good long highway run last night out to Hope and back (about 300 km round trip)... First extended highway run since the rebuild.
Everything feels GREAT cruising along. The revs are definitely a bit lower with this transmission than my old one - I'm around 2600 RPM at 120 km/h. Oil temps were just a hair over 100C and EGTs around 325-350C when cruising (about 210F / 650F) which I think is pretty much perfect. Cruise boost is set for about 45 kPa (6 psi).
I still have a bad TPS that comes and goes - when it is working my boost control is perfect
I've got a new one coming but man they are HARD TO FIND big time - seems this particular sensor was only used by Land Rover themselves despite it being manufactured by Bosch. Mine has a broken wire internally on the ground so the ground connection goes from "working fine" to "some resistance" to "completely open" which in turn makes the controller think the pedal is at any number of positions. My maximum vane closure map keeps the vanes fairly open at WOT to prevent overshoot so when it gets stuck thinking the pedal is floored I've got almost no boost. The TPS was only used for EGR control so most folks disconnect / remove them rather than go and buy replacements meaning they aren't readily stocked out there at your FLAPS.
Anyhow overall the first long drive was a success. The car feels great on the road - to be honest that's the first extended run I've been able to do since I had the rear suspension bushings replaced last year. Once you pop her in 5th and set the cruise control she's as smooth as can be.
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#269
by
vanbcguy
on 03 Jun, 2014 17:46
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Permanent boards for my turbo controller - minimum run was 3.
