Quote:
Originally Posted by ChasesDragons
Hi all,
For all who asked; H is the SI unit for inductance apparently.
I think there is £50 between IROLL's MAP and BOSCH's rebuild. Push to shove, I would go with Bosch just for the confidence in immediate aftersales support....but that is a LOT of money to just bet on.
There must be SOMEKIND of transducer out there which can be programmed to sense vacuum and fabricate the required inductance values to divert many of us from this mechanical mysery.
142 - did you build the MS system yourself or use Kurt's "Stealth System"? It might be the ultimate solution. But at about 300% of the rebuild cost.
Warmest Regards
U
|
OK, H is presumably Henries which is indeed the unit of inductance. However, it is the coupling between the two coils in the transformer inside the sensor that changes as the core of the transformer moves back and forth as the pressure changes that is the important factor. That is the 'response' that Dr Djet talks about mapping.
I saw prices a price range of 300 to 600 Euro for the Mercedes / Bosch rebuild service. If the cost is 300 Euro then perhaps its a wash. Scandcar lists them for sale on an exchange basis at a higher price.
https://classic-volvo.com/catalog/pr...nge-for-volvo/
The style of pressure sensor that Bosch used was quite common. The industrial practice when using this type of sensor was to apply a fixed AC exciting signal on the primary winding and then read the magnitude of the AC voltage on the secondary winding to determine pressure. The output signal changed as the diaphragm moved the core and changed the coupling between the primary and secondary winding. A modern low cost silicon chip MAP sensor coupled with a simple Arduino-like controller would easily emulate that type of voltage output device for less than 75 Euro. The problem is that Bosch got clever and instead of reading the output voltage they use the secondary winding to control current in a circuit which charges a capacitor which sets the pulse width of the injector pulse. That current control strategy is brilliant in execution, hard to understand how it operates; and it greatly simplifies the number of circuit components by eliminating the need to do an output voltage to charging current control conversion. It also precludes a relatively simple retrofit.
Winter here leaves me with idle time and I am cheap so I elected to build my own from a kit. My MS is now also heavily modified with sequential fuel and ignition control, E fan control, knock sensing and provision for meth injection (should I ever take leave of my senses) that a prebuilt system would be a waste.
If Kurt is still selling his system, he has put a lot of work into retaining the stock look. I believe he also provides a basic configuration which has value. You would likely be able to install it and then start and probably drive the car.
It took me two months of fiddling around before I was actually able to drive my car and about 2 years of tweaking before I eliminated the 'is it going to consistently start' under all conditions uncertainty. The one thing I would wonder about with his base configuration is cold starting. He is in Nevada so I expect that he has not spent a lot / any time configuring for cold starts below 0C. You might be on your own for cold weather starting. You do pay for the stock look and that initial configuration. If you are considering his system, I would find out what firmware he is running. I find that the MSExtra version of the firmware written by James Murray in the UK works much better than the original B&G firmware.
Note that MS2 is getting long in the tooth and rather expensive. When I built my first kit I think it cost around $200 - that ship has long sailed. There are some very good 4 cyl stand alone EFI controllers that are price competitive with MS2 - if you are inclined to do your own implementation and are prepared to go through the work of configuring and testing which is not insignificant.