hi gang just-n-time here,My question is the proper setting for measurement of this precious little bugger.MA.,volts, ohms? I have finished the EHA. and am still having a search problem on deceleration,and a little more roughness than
the engine should have.
I mark the position of the pot.and after making several readings in various settings,I tried to move the position of the pot and it made no difference in
the running of the engine.
I have been reviewing info fromThomH,stevebfl,patrick_mb, M.B.DOC, sborg.
Problem is that I can't get the ohm reading or the voltage nothing that even comes close to what they have had.
Removed the unit and the marks inside the unit are deep into the,what I would call resister's and if some one can explain to me how to adjust entire unit I would be thankful.jnt

Key on engine not running,top of sensor plate even with lower edge of cylindrical part of air funnel,plug installed but pulled back enough to measure voltage. Pins 1 and 3 should read about half a volt, at pins 1 and 2 read .2 to .5 volts.
Slowly push sensor plate all the way down and you should see the voltage rise continuosly to 5 volts at full travel.
Mike

Deep groves in the carbon usually means that the POT is worn out. That might explain why you cant get any good readings.

__________________
I got too many cars!! Insurance eats me alive. Dave

78 Corvette Stingray - 3k
82 242 Turbo Volvo - Manual - 270k
86 300e 5 speed manual - 210k
87 420sel - 240k
89 560sl - 78k
91 420sel - 205k
91 560sel - 85k
94 GMC Suburban - 90k
97 Harley Davidson Heritage Softail - 25k
00 GMC Silverado 1 ton 30k

Yes I think as much, but wish to do as much testing as possible.jnt

Thank you Mike,for your reply. koeo and do I need to unplug the EHA? Engine fully warmed?
Wish I had the papers I threw away I had a test done like that! but as I recall as the plate went down it traveled from 3 to 9 erratically just bounced up and down then as I got close to full open it went to 5 steady.
Tomorrow Miss Debbie have to go back up to Shreveport and when I get home I will make the new test, Will report tomorrow night.jnt

what model is your car and series?

cause I toy with the eta pot and have learned to test, use and repair it even in my sleep. I suffered that nightmare too, so was able to get all the proffesional help from the MB plant and some technical adviser from Bosch, plus due dilegent.

COOL, The car is a 420sel and a 1990. the pot ends in 035

JNT
The test I described is done with the plug connected. Readings with the plug off mean nothing! Look for a smooth transition from full closed to full open. The sensor pot is available on many sites on the web.
Mike

Great Mike,the test will not come even close to those numbers.
KOEO 1&2= 107.2, 1&3= 4.77, 2&3= 4.67 those are neg.on pin one and on pin two to get the 2&3 reading
KOEO ground lead to air mass body,
1= 16.5
2= 123.7
3= 4.79
I have a new meter from sears and tested the duty cycle at 60.2% at idle and at 2000 the EHA is -0 to pos. 0
+.01at 2000 so all that area is in good shape.

I know the leads to the pot must be on but I was referring to the EHA?

Well the new unit arived and I took ohm readings from the old and the new,I have placed the new one on and set the voltage to .67. This has not changed the low end serch but a very slight amount, so my next question is should I reset the trimpot, so it reads the same ohm as the old unit?
old was 94.7ohm, and the new was 57.2! jnt

Setting is I would say fair,the engine has a very slight roughness at start up, the cold start roughness feels like choking from to much gas, it will last for 3 seconds and runs up to about 900 rpm then settles to 800 then 750 for maybe 10 seconds then settles in at 700,once in gear it falls to 600 to 650. almost completely smooth just a slight roughness all in all I am pretty happy with the performance and the mileage of 19.5 mpg.JNT

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