UPDATE 5 JUL 2010
I have been experimenting with injection event timing to clear up a slightly uneven idle (although much better since MAP filtering was enabled in the "ECU Calibrations" dialog). Also, I had a slight hesitation under light to medium load from 1800 to 3000, although Lambda values were spot on or even to the rich side.
This made me look at the actual injection event. Although much has been said about the relevance of pre-injecting against a closed valve/closed valves, other developments like injectors with very accurate spray patterns (like Audi V6 Biturbo) point to the relevance of starting the injector just as the valve opens - what would be the relevance of the spray pattern, when allowing droplets to form on the closed valve?
Anyway, having an engine with an uneven number of cylinders, and working on the assumption that VEMS has simultaneous ignition and injection events (basically at TDC, although ign is obviously moved forward based on the relevant table), there is no logical way of injecting on or after TDC with a 5-cyl. engine.
Engines with equal numbers of cylinders almost always have 2 pistons at TDC at once, so you just move the injection event to the cylinder that runs along with the one having ignition. 5-cylinder engines do, however, have 144 degrees between their conrod journals, and no 2 pistons move together. This means that no matter what, the cylinder will always get fuel about 36 degrees before TDC, meaning well before the valves have a chance to open.
I know that this is not the proper way to do it, but in attempt to solve the problem, I moved the first trigger tootht to 5 (originally 0), meaning an artificial TDC-movement of 40 degrees away from the index tooth (my tooth width is 8 degrees on the divby3 trigger). Then, I moved degrees from index tooth to TDC from 62 to 58, because I wanted just 36 degrees, and 36 can't be divided by 8. Pushing teeth from index tooth to TDC ahead to 98 and leaving the first trigger tooth also worked, but I was warned against having a value that close to 100 for "TDC After the Trigger", so I found this better.
The only other thing to do is to move the entire ignition table 36 degrees forward (and edit cranking ignition from 10 to 46). The whole thing looks suspect on the VEMS gauges because of the very aggressive timing values shown (takes some getting used to that they are actually 36 degrees later), but the car runs perfectly and startes everty time. There is still a bit of roughness, but only at exactly 2000 rpm. This may be caused by a need to move back the injection even more due to airflow factors. I havent tested that yet, and the possibilities are limited due to the fact that my pre-ignition window is already 36 degrees smaller than before.
Would it be possible to make the injection event start adjustable to the opposite side of TDC? I would imagine that some 4 og 6-cyls with funky cams would benefit from this as well.
Logs and images will follow shortly...
Thanks!
\Alex
UPDATE 18 JAN 2010
Experimenting with ROUND (used as display for v3)... writeup will follow shortly.
Built a really simple adapter to avoid disconnecting/connecting PC and ROUND.
- The red pushbutton allows changing between the two.
- assuming: it's a 1-circuit, 2 position switch, not a button. The round RX is either fed from the PC, or the GenBoard/VerThree depending on this switch.
- Round-TX can go to PC-RX permanently. It should not cause physical damage at least. Although incoming data before device opening might disturb poorly written (most prolific windows) serial port drivers. (might require closing + reopening tuning application, or reconnecting the USB device: or was this that actually started you to make this switcher ?)
- Actually, I wanted to swap between round and the pc. One button position has the pc connected to vemsv3, while the other has round and vemsv3 connected. Although it seems ok to hot-swap, I make a habit of switching off the ignition first. The actual switch can switch conections from 3 input pins to 2 different sets of 3 output pins or vice versa.
- Think it better to switch off IGN before switching over, but not sure if it is really necessary.
- no, it should not be necessary. The RS232 chips should survive +-12V on the RX signal, even if unpowered.
Running Motronic 55 pin conversion on one S2 with distributor and another with COP (both 3B engines). 1.1.44 has worked well on both.
Figured I'd try 1.1.54, but the tables for spark and lambda got messed up in VemsTune every time the VEMS had been turned off.
In case anyone else has the same probs, just edit the VemsTune INI-file:
Search for "page 3". The table definition array for lambda has 2 entries that look like this: [8X8] - replace the uppercase X with a lowercase x.
Search for "page 4". The table definition array for spark has 1 entry that looks like this: [12X12] - replace the uppercase X with a lowercase x.
This did it for me.
If your OS moans about editing rights, uninstall VemsTune and install it again outside the "Programs" folder or in an entirely different partition.
UPDATE: 27 OCT 09
Updated the car with distributor to 1.1.62
A few problems with "Acc enrichment" and "Cold starting", but they are all sorted out now, and the car starts and runs great.
Idles excellently.
TODO: Check if boost develops as expected, and if so, update the other car as well.
See running vemscfg below
UPDATE: 29 OCT 09
Still need to fiddle a bit with boost, but I must say that I am very impressed with 1.1.62. My development car (Audi 5 cyl. turbo with distributor) runs better than I had ever hoped for.
Great job on the firmware and VemsTune you guys, and many thanks to Peter Jensen for useful suggestions!
Here is a pic from my other project, a rallyecross Audi S2 that I have modified with coils from a late model S4 V8.
Almost a direct fit with modest tweaking of the coils and a slight grinding-down of the valve cover. In case anyone wonders what the distributor is still doing there, it has to stay for now because it holds the camshaft sensor.
UPDATE: 5. NOV 09
Slight problem with one VEMS box in the race car.
When everything is cold, the VEMS seems to get stuck in bootloader, and the VEMS won't start up. After a few tries, it then boots up.
If IGN is then turned off, VEMS won't boot right away (IGN back ON) unless I wait about 30 seconds.
When the car is warmed up, the problem seems to be gone. The box has 1.1.44, but considering the temperature sensitivity, this seems to be hardware related rather than software related?
LCD just shows completely lit line 1 and 3 when the problem occurs.
Thanks for any thoughts on this.
How long is the RS232 cable ? It sounds like a capacitive "loopback". Plug in a DSUB9 male connector with a 10k resistor between GND (pin5) and RX (whichever pin goes from PC to ECU). This should prevent capacitive loopback (we've only seen this with 1.5m+ long serial cable, but ....)
Excellent, thanks! The cable is very long. It was routed through to the rear of the propshaft tunnel, but I thought it better to keep it away from high current wires, so it ended up having to be 2.5m or so.
Hi Alex any chance I could grab a copy of your vemscfg 1.1.62 please? you can place it in my file area under the Jamo directory
Running vemscfg config and tables:
Note: I was just tweaking idle under load (fan on etc.), so that may not run too well, and boost is not done yet. It boosts, but I am not sure if it limits where it is supposed to. Haven't had a chance to test it yet.
The file is from the distributor version - don't forget to make changes if you run COP.
http://www.vems.hu/files/MembersPage/AlexHoy/Alex_3B_S2.vemscfg
Acc enrich and idle are often not trivial to get good.
- note that boostalt_ref table bins are detached from ignadv bins since 1.1.63 - this is very useful in boost_alternate relative mode (VemsTune vemsv3.ini changes apply of course). Other modes and normal (PID) boost output behaviour uneffected.
Many thanks it's just for reference, looks a good map congrats you've convinced me to go with 1.1.62 for my ABY
It is a bit on the rich side under load, but the thing takes off like a rocket. Killed the original friction disc during the test stages, and it had only 16K miles on it :-O. The torsion springs were squashed and seemed to be lacking about a fourth in length. "Definitely a torque-related failure", as the SACHS dealer put it.
Using a diesel block, this is something you will have already addressed, I assume? These engines are capable of producing torque way beyond the capabilities of gearboxes and driveshafts.
I'm running a sachs sintered racing clutch, the car will produce roughly 750+ nm of torque at 2 bar boost!. I think however i'll back the boost of to a lower level to preserve the gearbox as noted although the late ABY and RS2 6 speed boxes are quite strong