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This VEMS is being constructed to replace the now useless Rover MEMS1.9 ECU on my Group A rally spec Classic Mini.
A Little History
The engine is a Single Point Injected, standard stroke, 74mm bore transverse Rover 'A' series engine http://www.austin-rover.co.uk/engineaseriesf.htm . Everything was running well enough before fitting the Ex works ( http://www.wpm.co.uk/worksminis/ ) group A cylinder head, which this particular head from the BMH ( http://www.bmh-ltd.com/ )prepaired cars, had seen and completed the Monte Carlo Rally and the Nurburgring. This head pushed the compression ratio further from the original CR that the MEMS ECU had ignition maps for.
This problem was evident when I first built the engine when the CR went from the factory 9.4:1 to 10.5:1. Onset of knock was evident on 95 octane unleaded and just about normal on 99 octane. So I knew something had to be done when calculating the CR with this head to be 11.2:1.
What i did to try and overcome the problem of knock was to remove he reluctor ring on the flywheel, retard it by X amount of degrees and re install it, thus retarding the ignition advance right across the map
This was good in theory, and probibly still good if you dont retard by too many degrees, as I found out!
I retarded by five degrees, not realy knowing that the cold crank degrees is set to 5. So, cold starting on a cold, rainy winters day, its a bitch to start to say the least. I retarded by too many degrees. once the engine is running its fine, though suspect that its not performing as it should.
This is where VEMS comes in. To bin the MEMS and replace with a programable ECU and still start, run and drive as though it were a factory ECU for minimal cost. Megasquirt had always been considered, but a fellow TurboMinis? ( http://www.turbominis.co.uk/forums/index.php ) member posted about VEMS. I was curious, and, well, here I am.
Hoping this is going to be a very exciting project unvaling that lost power of my engine.
Baisic spec of the Engine Management System
Unipolar Stepper Motor ( more to come on this, I have been researching for some time using Unipolar motors as Bipolar)
Throttle body single point injector, Low Z
Knock detection (mainly for the future turbo engine, experimental at this stage)
EGT (mainly for the future turbo engine, experimental at this stage)
Original coolant temp sensor
Original Air temp sensor
DIS coil pack from an MPi Classic Mini ( ditching the dizzy and coil)
Original crank angle sensor ( reluctor modified to give 36 -1)
I am going to butcher and modify a factory engine loom and hybred it with an engine loom from a late Rover 820 Turbo with DIS and mount the ECU inside the car
V3.3 GenBoard Flyback path:
Stepper IC orientation:
The 10uF (1210 size, 35V) capacitor was already installed (not in the rescue kit 2):
The transient supression diode (max 36V) is installed with (stripe-marked) cathode connected to the onboard flyback rail; the anode to the injector common (+12V). Our standard is 30V bidirectional that is easier to install (works in either direction)
Ok so a lot has happend since i last updated this page, I will get round to updating soon with finer details, but for now, i can say that ive had the engine running for quite some time, had it dyno'd and figures are 95bhp and 101lbft. I have been having issues trying to get the acceleration enrichments somehwere right, this is ongoing. I have also been having issues with stalling and backfiring. As I say i'll update this and explain in more detail.
I have also swapped the Genboard over to the Abulos case for the extra space to install a Peak and Hold injector Driver board designed by Jean Belanger over on the MSEFi forums. This is curently installed, wired up and just needs testing.
I have also had issues with the primary trigger, where i blew the P259 chip and had to remove it, I ended up swapping over the outputs served by the chip to the spare injector drivers. I have now replaced the chip and everything is working again.
Since january a lot has happened.
I attended The Minis V's Beetles shoot out at York Raceway http://www.york-raceway.co.uk/ On Easter Sunday this year. I had intended to go with VEMS installed, but as it took me so long to get it running on the car, it left no time to tune it, so I put the OEM stuff back on.
Two weeks later there was the Minifinity http://www.minifinity.com rolling road shoot out at Minisport http://www.minisport.com . I left the OEM stuff on the car for this. The Miniworld Magazine http://miniworld.co.uk were there as well. 17 Minis showed up one of which was an 8 valve Vauxhall transplant and there was also a Vmax Scart http://www.vmaxscart.co.uk supercharger conversion. Out of the 16 A series cars i was in third place, he he, with 100bhp at 6800rpm and 87lbft at 4600rpm
It was after this I pulled the engine to install the 16v engine and fit a fibre glass front end. BIG mistake on the front end, someting i will regret fro some time to come, and is part of the reason I never got the 16v engine in the car, really big downer!!
As you can see in the picture above, the wiring loom is installed. The VEMS is mounted under the dash and the loom is completely new
I ended up putting the 1400 back in and set up VEMS on this. I had one week to get it driveble and get it to the dyno. There were several problems along the way. The main one was i had left the high flow fuel pump in the tank. With the TBi only using 1 bar fuel pressure and probibly about 1/4 of the flow capebility, it was just too much for the regulator to handle, to the extent that at idle the AFR would run away rich, stalling was a big problem and restarting was difficult, lol, as were 2 foot flames seen from the exhaust when starting, LMFAO. Changed the pump out and set the VE learn agressive. I managed to get it at least driveble so i could get it to the dyno the following morning.
Mapping seen the ignition and fueling optimised with a final power figure of 95bhp at 5400rpm and 101lbft at 4600rpm
Mapping was done at WGT http://www.wgtautodevelopments.co.uk/ on the Dynapack dyno
Top end is a little fuzzy, lol, i was nervous for the engine, lol, i neednt have been, it revs to 7k no problem
'Really Really BIG Problem With WBO2, NEED Help PLEASE'
Siamese Inlet Port Injection Problem
This is going to be a very long winded and complex subject, LOL
Peak and Hold Injector Drivers
This is a possible solution to drive your Low Z injectors.
The Rover Mini SPi is fitted with a 'throttle kicker' stepper motor for idle air control.
LCD Display alternative
Looking for something a little bigger?
An Idea for data point identification when data logging]