Hi :)
Need som help setting up my VEMS Motronic-55, on my AUDI RS2
Engine info:
- It`s an ADU engine, 5 high output coils with built in drivers.
- 720cc high-Ohm injectors. I have some 1600cc (4.5 Ohm, don't need power resistor)
- custom cams and ported cylhead
- JE pistons
- H-beam rods
- 82.5mm bore
- 92.6mm stroke
- Turbonetics gtk 650
- 89mm exhaust
- 034 motorsport high output coil pack (5 coils) standar POS not used.
Okay, got my car running with vems :) But now i got a little problem.. I had a little accident, and managed to change the rpm constant to 5000 with a running engine.. The engine stalled, and now i get RPM=0 during cranking. What could have happend? I changed it back to 2400, but no signal.
The rpm constant is used to calculate the RPM, that is used for
- displaying, logging
- table lookup
- comparing against threshold (eg. revlimiter, overrun fuelcut/fuelresume)
It effects ignition and injection, because of table lookup (different value in table), but otherwise (if trigger_tooth and tooth count, reference teeth and other related variables were unchanged) I see no reason how it could cause permanent non-running.
Maybe some other variable was also changed ? Dump the config with mcd, mct and publish it, than it can be diffed to original known-running config. Also, log is very useful to detect conditions (commanded PW, dwell, ignadv, RPM...)
You can start again, uploading the config that was running (to overwrite any other variable that was unintentionally changed).
More info:
I managed to get the car starting again. No other variable was changed (100% sure) I dont think this was the reason for the car not starting again.
It seems to me that the battery voltage might be the problem.. While cranking, the car dont get any RPM signal. But when i hooked up the battery charger, it got rpm signal right away.
While cranking i messure:
11 volts on battery
10.7 volts in megatune
and I have calibrated the battery voltage with no load att all. only IGN ON.
Does this point in direction of weak rpm signal?
- low VBATT should not prevent reading trigger, unless it is lower than 7.5V
- except if your HALL sensor fails to work for some reason, check the HALL sensor power (and HALL sensor output if you can, with scope or soundcard).
It would be nice to see the HALL-signal in relation to crankhome-VR pulse (maybe the HALL is somehow out of position and masks both crankhome-VR pulses ??)
Measure the crankhome-VR
- sensor resistance
- input DC voltage (ignition on, engine off) to see what pullup resistor is used
- DC voltage should be min (+ or -) 300mV (but min 400mV is better, appr 12k pullup to +5V), otherwise ghost on crankhome-VR can prevent starting
- note: if the sectrig uses the other method, 1k pulldown to GND and LM1815pin5=5V than the min 300mV is not required. But measure anyway.
For primarytrigger VR (although not as sensitive as crankhome-VR), at least measure
- sensor resistance
- input DC voltage (ignition on, engine off)
As always, detail wiring, firmware revision, mcd, mct, logs (wheel error?) and all relevant data, see IssueReports
Q: So my high Ohm 720cc injectors need power resistors? I think mine is the same as sold in the vems shop. Siemens deka 727cc@ 4bar
A: as you write, Siemens deka 727ccm (@4bar) is actually high impedance (if same as in [webshop], 12 Ohm => you don't need power resistors.
Q: I have changed my mind, and want to go for the NTC type IAT sensor. My vems is set up for the PTC type.
What to do?
A: Remove the additional pull-up resistor on the PCB which is mounted on top of the regular pull-up for the IAT analog input. Other people might clarify with pictures of the PCB and where you must do the work.
A: I allso recived an e-mail from vems shop now:
Fortunately this is easy. Remove endplate (endplate only, 4 screws).You see a small resistor near the main processor, close to board edge, parallel to board edge.An 510 Ohm (0805 size SMD) resistor is piggybacked on a 2k7 resistor.Remove the 510 ohm, and you just converted back to a normal weak pullup suitable for NTC.
I guess this would be easy.
Q: I have some msq files for the motronic 55, but i can not understand the ignition outputs.. what is H[2]? and what does 04..00 stand for? Does this have any thing to do with the fiering order?
A: The H2 is the exact firing order of the ign outputs more info at this page http://www.vems.hu/wiki/index.php?page=GenBoard%2FManual%2FDigitalOut%2FTable
If the car is Audi s2 you will find some useful info in this page http://www.vems.hu/wiki/index.php?page=MembersPage%2FPeterJensen/AudiSwiring
Regards Peter
Use this config: http://www.vems.hu/files/MembersPage/MattiasSandgren/OskarNilssonsAudiSFour/oskar_optimized_power_20080506.msq
The ignition coil firing order can't be questioned, this is how it's wired to work with the pnp VEMS box using the stock harness and the trigger settings. You must use the settings from Oskars msq file.
About the the injector firing order, I updated the VemsAudiAan page with more information about that. The table is correct in that it fires the injectors in the correct order. You can rotate/shift the table any way you wan't - it won't make any difference on this engine. True sequential injection control with a table for injection end angle is not required.
This means that : 8,4,2,1,16 = 2,1,16,8,4
Or as in Oskars msq : 16,8,4,2,1.
These three examples are all in the same firing order, only rotated/shifted.
Q: What firmware to use? can i use 1.1.23 12x12?
A: Don't use 1.1.23. See this page: MembersPage/MattiasSandgren/OskarAudiSFour
Download 1.1.27 on the MegaTune page and go from there.
Q: How to upload tempsensor files?
A: You have to use the tempsensor_upload script that comes with the MegaTune package to upload a firmware containing the correct temperature tables, see EasyTherm and EasyTherm/SensorTable.
Q: When i downloaded megasquirt, there was a PINOUT picture included.. Is there a simular picture for the Motronic 55 plug?
A: Begin reading here: VemsAudiAan Take a look at the spreadsheet and as hinted earlier you can find a picture here: MembersPage/PeterJensen/AudiSwiring