Project page for (another) VW GTI/16v swap, Turbo
Car: 1994 VW GTI
Engine: ABA(8v)/9A(16v)
ABA (8v) Engine block, crank, 60-2 trigger wheel.
9A(16v) Cylinder head.
Built motor (forged pistons/rods) Garrett GT35R .81 a/r T4 turbo.
Custom EC36/EC18 Wiring harness
- details ??
custom FJO fuel injector driver
- connection details ?
- do you know that injector outputs can only pull to ground ? (that is pullup might be needed, perhaps internal in the FJO injector driver, did you think about this ? Measure voltage when inj output inactive)
VEMS v3 webshop assembled
1.0.73 Firmware
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Update
Many problems! Likely related to the mcp3208 damage (caused by insufficient wiring 99% of the time).
- Twice, shortly after making a change (what change?) in Megatune, the ECU "locks up" and causes the injectors to stay open and fuel pump to run, hydralocking the motor.
- In my case it cost me a USD $280 Bosch LSM11 O2 sensor!! Also new oil for the engine (twice), and several hours lost (work and sleep).
- How can it be prevented?
- properly planning an install before doing the wiring is the way to go, it often saves a lot of bucks.
That means to plan
- wiring (inputs and outputs)
- choose firmware and trigger setups to start from (reference to similar setup)
- matching outputs h[0] and h[2]. If you instruct the ECU to activate an output and the outputs control injectors and fuelpump (it is possible to activate max 8 injector outputs at the same time, see GenBoard/Manual/DigitalOut/Table )
- in case of any output issue, all output channels are interesting (mcd dump, variables ending with _channel except shiftcut_channel that is not output but input selection)
- note: it doesn't make sense to install LSU4 sensor for first startup (plug the whole with a bad sensor). When the engine starts and idles, the wideband sensor can be installed (after any calibration)
In case of any problem anyone who wants to help or you expect to help absolutely need to get the plans. A question like "what is wrong with X" (a certain setup) is just a waste of time "without telling what X" (the given setup) is. See IssueReports for checklist so nothing is missing.
It is best to publish for review (split to subsystems at least trigger, inj and ign) before doing wiring and powerup.
HW connection problem is also possible
- bad grounding ?
- eg. "stealing input switch ground" (not from EC36pin26 ground but) from chassis while some or all grounds are missing (or chasses to engine ground missing ?)
- flyback ?
- overloaded output ?
- extra analog input out of range (pullup to +12V or direct +12V applied ?)
- perhaps using battery break switch to disconnect battery while engine (and alternator) is running ?
- This is only for accident. (especially if there is no external max 1A fuse and 18V transient diode in the harness)
other possible (though unlikely) causes:
- using different megatune (1.1.x for 1.0.x firmware ?)
- almost flat battery ?
MCP3208 damaged
- After turning the power OFF (how exactly?) for a few minutes, everything was fine the first time, however the second time I think the ADC chip was damaged.
- this shows that quite certainly something was connected wrong. Bad grounding ? or >5V (+12V ?) applied to extra analog input ?
- I now have no 1) EGT 2) Launch Control stuck ON
- no surprise, this confirms mcp3208 was damaged. It is also possible that the main processor got partially damaged (could also explain the injector outputs)
- I am using an external MAP sensor, how is this still working?
- the external MAP sensor uses a direct ECU analog input (not an mcp3208 analog input channel)
- The wideband O2 readings are OK at idle and low engine RPM, but jumps around greatly at medium RPM and higher, making the sensor unusable. The pumpzero_pw and Nernst values were used as supplied with the VEMS, and the sensor was calibrated to 20.9% O2.
- What could be the cause for this problem?
- most likely: doing the wiring before planning it => killing mcp3208 and perhaps other internal with bad connection
- possible note is I used the Fuel Injector relay output (terminal 87, shared with fuel injectors and the FJO fuel injector driver), to power Pin #3 of the Wideband O2 Sensor
- good note. Unlikely to be the cause of the problem though
- To allow the car to be tuned, I used an analog input for my Autronic exhaust analyzer. I set the analyzer to 0-5v, 10-15 AFR so I could view the Megatune logs in voltage and add a "1" to get my AFR. However I could not do this after the ADC chip was damaged.
- this is one of the operations that could damage the ADC chip.
- What does the "Map Multiplication" in Megatune do exactly?
- the pulsewidth would be multiplied "behind the scenes" with MAP. The fuel VE table often becomse "flat", but not always very flat especially at low kPa. VE value approx. 50% at 40 KPA, 200% at 250 kpa.
- note that this question is also a "what is happening in X" without telling "what X is". Particularly without the possibility to review the injopen (and rampup, battfac, etc... settings).
- I found that the logic level Ignition output does not trigger an MSD ignition, I had to use a 12v power output.
- this is well possible, actually a common method to use IGBT power output
- I ended up changing the ignition to a coil pack using 2 12v drivers
- The car runs very well when it is running.
- what are the tps bins used? (the lowest one is most interesting, obviously). Is the TPS signal otherwise clean ?
- and I need to work on the startup a little.
Car is up and running on VEMS
Currently using 60-2 crank trigger only, semi batch fire injectors
Rochester 1000cc injectors, FJO external Injector Driver unit
VEMS 400 kpa External MAP sensor
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VEMS #1724 Order Specs:
Assembled v3.3 controller
- 1-wire interface: no
- Flyback: 30V flyback
- ignition driver: 4
- Knock and EGT: yes
- LCD connection: yes
- MAP connection: offboard
- primary_trigger: VR
- secondary_trigger: HALL
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Build notes:
Board_version=v3.3
Serial_nr= 1724
pump-= 4.12V
wbo2_pump_pw_zero=0x67 (103 decimal)
wbo2_nernstdc_target=0x86 (134 decimal)
pump+= +0.9mV/200 Ohm
AREF=4.9V
(C103=1nF, no D100)