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Old 09-16-2002, 08:42 PM
Posts: n/a
Of potentiometers and men

1985 190E 2.3 with CIS (Cursed Injection System). a few questions after an entertaining weekend:
1. Potentiometer reading between 14 & 18 pins on the potentiometer 4890 ohms non-adjustable, and about 50ohms over spec: enough to replace?
2. Readings between 14 & 17 pins: 750 at rest, 5670 at full deflection, as high as 5690 dear full deflection. Enough to replace?
3. Adjustment of potentiometer, reputedly very sensitive, yields only about 150ohm at rest, and less than 20 at full deflection is this right?
4. Checking the EHA, the final adjustment of control pressure, and therefore the last modifieir of fuel output by the injectors, I can modify its values correctly when testing for full lean and full rich conditions at the oxygen sensor, and the system "floats" when everything is connected, indicating the eha is correctly adjusting for downstream readings and engine operating conditions. But at wide open throttle, instead of going to 7-9mA, it fades off to about 2, effectively leaning the engine out. I dislike jumping to the conclusion that the computer is at fault, but the throttle switch works, the idle cutoff is working, thermal sensor and barometric sensor all seem ok. Fuel flow and pressure are at least 150% of minimums. I did find a leaky coil wire, and two if the injectors had lousy patterns so they were replaced, along with the injector seals, all of which gave me a better idle and part throttle, up to about 3200rpm under light loads, but the performance end of the throttle just isn't there. Oh, compression is 145 - 160psi and plugs indicate sooty misfire.

Man, I hate being ignorant, but this is just at the periphery of my bosch capabilities. ANY suggestions? ( other than offers to buy it for parts, it's still an ok vehicle at 151k)
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