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Calibration & Mapping / map vs alpha n?
« Last post by Seight-v8 on April 12, 2021, 11:09:23 pm »
hello all,

just been reading a fairly new rover v8 tuning book......and the section on ECU tuning, says that non turbo cars, with map readings under 65kpa, and large overlap cams, would be better on ALPHA N (TPS) maps instead of speed density maps......

So if this is true?, then mine would meet all of these requirements......but ive never used anything other than SD map based.....

i don't want to start down a road that makes it worse and has other side effects......

So thought i would ask.

Modifications and Repairs / Re: Atmega128 replace?
« Last post by jrussell on April 09, 2021, 12:12:10 am »
You need the bootloader and you'll need to email with the serial number of the board. Including a pic of the PCB so they know it's not a counterfeit would be a good idea as well.
Modifications and Repairs / Atmega128 replace?
« Last post by savke989 on April 09, 2021, 12:07:42 am »
Hi to everyone. I have got a Vems unit from racecar that had an crash, case is brocken and oil/water get in. I am pretty sure that Atmega is dead. I am electronic engineer and i can replace the chip but i dont know what firmware was in it. Programing is not an issue i have programer for atmega128. PCB look like v3.8.
There is schematic for v3.8 on vems site and i checked all power and gnd pin to atmega everything is ok but chip is dead. Is it posible to just flash newest firmware?
Fuel Injection / Continued setup and troubleshooting.
« Last post by vball23 on March 28, 2021, 11:07:32 pm »
85 Porsche 928 with 89 928 S4 engine. Using factory 89 wiring harness. Went with coil on plugs also.

I am working through some issues and would like to ask the community, rather than always bothering the same few people that I keep pulling in. I will keep hitting them up as they are great resources, but this way I can give them a break from my questions.

TPS has been calibrated. Ignition coil functions have been tested and verified. Battery fully charged.


WB02 will not calibrate. I have tried 2 brand new sensors, same result. The calibration tool says "Heating", never changes and tip of sensor never gets warm and the gauge never moves from zero. I have tested the wiring, got the expected voltages on each and did a continuity trace between the connector wiring and the VEMS EC18 plug. All good. I am not sure how power is supplied to the sensor heater, ie what relays and fuses are involved. Per the fuse chart, I have replaced fuse 42, which is for fuel pump and 02 heating, and I have tried the calibration with the FP relay in and also with it out and jumpered so the FP is running. No luck. Any ideas where to look/test/etc?

2nd issue, injectors never fire. I have tested each with a noid light, using test function from VEMS and also while cranking the engine. I have verified wiring is correct and continuity is present on each. This is wired for factory setup on injectors, so EC36 pin 7 is being used for injector output. How can I test the injector impedance for the injector circuit? Any other places to troubleshoot, CPS, or anything else?

General Discussion / Audi automatic gearbox
« Last post by 20vtAndy on March 16, 2021, 01:45:13 am »
can a  vems v3.3 aan be used with an Audi 1995 2.2T urs6 automatic TCU gearbox controller, I Am looking at my options and this is one of them...
Configuration / Delaying ignition during starting to prevent kickback
« Last post by RogueEngineer on March 12, 2021, 08:30:52 pm »
Running VEMS on an '85 911 that's been converted to twin plugs & wasted spark coil backs.

Max cranking RPM is about 250 RPM according to the sensors.  During the engine speed ramp up when I hit the started I get significant starter kickback - typically 3-4 times before the engine 'breaks through' and starts up.  Currently running 0 crank spark advance.

I would like to figure out a way to disable/delay ignition for a few cycles so the engine builds enough speed to trigger reliably.  One thought is to drop the flood clear TPS value low, and start with my foot on the gas, briefly, until I hit max starting speed, and then 're-engaging' the fuel system.

Any other clever ideas?

Ignition / Mitsubishi Evo 5 no spark fault
« Last post by Davidol on March 07, 2021, 11:39:05 pm »
Hi all, first post on behalf of a mate so bare with me

Bought a Mitsubishi Evo 5 fitted with a VEMs ecu, been running fine until last weekend, mate jumped in passenger seat and car cut out and will not restart. It’s a ex rally car and the wiring in the footwell is frankly shocking so we assumed wire had been dislodged and caused issue but we cannot find the fault. Car runs external twin Bosch fuel pump setup - pumps run but we have no spark

Bit of diagnostics with the multimeter tell us we haven’t got 12v at both the cam position sensor (OEM Mitsubishi) and also the crank sensor (again OEM)

Plugging the laptop in also confirms ecu isn’t displaying RPM when car is cranked using VEMs software

Confirmed the continuity of both plugs back to the ECU so any suggestions on where to go next? Looking at the wiring diagrams it looks like the ECU supplies the 12v directly so is there an internal fuse as all external fuses are fine

Thanks 😊
Wideband & EGT Gauge / Re: Round V1 Gauge Fault
« Last post by Poloace on March 05, 2021, 08:40:21 pm »
I have tested on the bench supply with psu replacing the 78L805 5v reg however in removing the hard potting glue over it I have damaged and remove the top of th epart next to it, its either a transistor or another voltage regulator can anyone help with a part number it is a 3 pin part ( looks like a sot23 component)

The gauge when running on the PSU I can now see it on VEMS but the LED on the display is a bit dim, I have also added 12v onto the inputs in case they direct feed anything else.

Would be nice to be able to fix this so I can get on with testing tomorrow.

Wideband & EGT Gauge / Round V1 Gauge Fault
« Last post by Poloace on March 05, 2021, 05:58:21 pm »

Can anyone confirm the maximum voltage the round gauge can take? I used a car mains powered jump starter on my kit car and it put 20V on the battery later I found me Round wideband gauge was not functioning.

I have managed to dismantle the gauge ( I can see it is potted and not really suitable for repair) I was hoping that may be I had just killed the voltage regulator on it  could you advise its part number.

I have equipment for SMT rework so should be able to repair, desperate to get it back on car as was in middle of tuning prior to UK MOt test.

Best Regards

General Discussion / Re: I want fire and flames rev. limit
« Last post by davide on March 01, 2021, 10:51:43 pm »
Hi Gunny,
thank you so much for your replay and sorry for late answer.
I am living in Verona but we can't move due to Covid19 restrictions so we try to do what it is possible by messages.
I connected the idle valve as you suggested, now I am going to set inputs.
Last year I had a fail with V3.8 serial number 11010 order id 11521.
The ECU was sent to VEMS for repair and I got back a V3.8 serial number 19888 free of charge.
I haven' t received any EC18 pinout sheet .
I need to switch to GND n° 4 analog in chX provided with pullup, for ALS, MAP Switch, shift cut and launch control actuation.
How is it possible to know if my board is equipped with standard analog in ch 2-5-6-7 pullup config?
Thank you very much,
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