Hi, some of you may know me for the mad scientist work I've been doing with the D-Jetronic system:
http://members.rennlist.com/pbanders/djetparts.htm
http://members.rennlist.com/pbanders/manifold_pressure_sensor.htm
http://members.rennlist.com/pbanders/ecu.htm
I've come up with what I think may be a fairly simple way to characterize and adjust the D-Jetronic manifold pressure sensor (MPS) by an electronic calibration method. The only test equipment required is either a Wavetek LCR55 ($190) meter or a Wavetek 27XT multimeter (as low as $30 on Ebay), and an Actron hand vacuum pump with gauge ($30 at your FLAPS).
The inductance of the secondary coil is measured over a vacuum range of 0 to 25 in. Hg. I've include a URL to a plot I took of the new rebuilt MPS in my 2.0L car:
http://members.rennlist.com/pbanders/MPSPlot.gif
The blue line with the diamonds is the actual measured response, and the violet line is a linear fit to the region from 6 to 17 in. Hg. Using procedures in my MPS document (URL at the top of this message), you adjust the part load and full load screws to obtain the same slope and intercept, and full-load delta at 0 in. Hg. The measurement takes less than 5 minutes.
I've tested two of the 043 units, and they have essentially identical characteristics. You can also use this procedure to document adjustments you have made to the MPS for increased displacement or other tuning.
Where I need YOUR help is in gathering some units to build the set of standard calibration curves. What I'm looking for is new or newly rebuilt MPS's with the following Bosch part numbers:
0 280 100 049 1970-1973 1.7L
0 280 100 043 1974-1976 2.0L
0 280 100 037 1973 2.0L (and 1.7L)
I really need the 049 and 037 units. Here's what I ask:
- contact me by email at pbanders@yahoo.com if you are interested in helping out
- ship your new or newly rebuilt MPS to me, insured for replacement
- I'll do a 5 minute, non-destructive inductance characterization
- I'll ship the MPS back to you the next day, insured, and will reimburse you for your shipping to me, and include a copy of the test results (similar to what you see at the URL above, including the linear fit data and full-load delta calculations)
- Your assistance will be acknowledged in the updated version of my MPS document that I'll create once I have the data set
I would like to have at least 3 of each type of MPS above to establish the characterization curves. If I get enough participation to satisfy this need, I'll let you know if I don't need any more units for testing.
Help out if you can. The MPS is the most critical sensor in the D-Jetronic system. Many have been tampered with, leaving owners no recourse but to drop upwards of $200 on a rebuilt or (gag) nearly $1000 on a new unit. A reliable and inexpensive calibration method can save a lot of money.
thanks,
Brad Anders