On my VSS signal to up the number of pulses from 9 per rev to 29 per rev - which is what the corsa ECU is expecting. The engine speed signal will be provided by the engine ECU.
In the course of my research for this, I have found out that the variable assistance is actually three separate maps in the ECU, Which are switched to be the active assistance map depending on the speed. The greatest assist gets switched to the 2nd, less assistive map at 18mph. The switch to the third, least assistive map happens at another, higher speed. I have yet to find out what this speed is.
The reason I'm interested in these speeds is that by changing the settings on the speedoDRD, you can fool the EPAS into believing it is going faster (or slower) regardless of the true VSS - hence tailoring the level of assistance to taste.
I'm working on a spreadsheet that will work out what multipliers are required for the exact same assist as would be expected in a stock Corsa, along with smaller and greater multipliers for increased or decreased assistance ranges, and where those cutover points would be.
I'll link to the spreadsheet once it's ready, if anyone is interested.
And if anyone knows what the cutover speed is from the middle map to the last map is, I'd love to know.
Joined: 12 Nov 2009 Posts: 359 Location: United Kingdom
Posted: Tue Jan 29, 2013 11:11 pm Post subject: speed sensor
Thanks for your information. I bought a Corsa EPS a few years ago for another ongoing project. At the same time I bought a potentiometer off ebay which claimed that it would adjust the sensitivity of the Corsa ecu. I have not yet fitted it to my original project so can not comment on if it works well. But I was planning to fit a similar system to my camper.
Keep the information flowing I am very interested and sure others here are as well
There appears to be two ways this could be done on my BMW based car - via the diff speed sender or an ABS ring on one of the hubs. I assume there would be similar pulse sources on a Van.
Regardless of the method, it does give you the opportunity to tailor the assistance, by electronically multiplying or dividing the pulses the speed signal source sends to the EPAS ECU - basically fooling the unit into believing its going faster (or slower) than it is, and hence decreasing (or increasing) the assistance range.
The spreadsheet calculates a number of possible multipliers for either of my pulse sources. If yours differ in the number generated per revolution, you'll need to use those, and then point the assist speed tabs to the correct entries on the wheels tab. You can also enter your own tire & rim sizes. It should then work out the approx speeds the different levels of assistance will work till.
I'm planning on trying the ABS route first, mainly as I'm re-fitting ABS sensors for a Traction Control system I'm installing - but also as there's the possibility that the 48 pulse per rev BMW ABS ring will give a workable range of assistance out of the box with no monkeying around with the signal.
Better crack on and get the column welded up now...
Joined: 09 Aug 2013 Posts: 1 Location: New Romney Kent
Posted: Fri Aug 09, 2013 3:50 pm Post subject: EPS Corsa B
Hello everyone, I am new to this so please be kind lol.
I am after the help of all you experts out there. My son bought a Corsa B 1.2 Auto 1999 a month ago for £200. The car passed an mot a month earlier so there is still 10 months mot left. Since he had the car the eps light is on the dash and the steering is very heavy. He has spoken to various garages near where he lives in Borehamwood but they all say that its an expensive job to fix. One kind garage who didn't charge him after looking at it said it was the torque sensor needed adjusting or replacing. Any ideas or thoughts on where he can get it done cheaply would be appreciated. Best wishes to you all. Tom
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