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#16
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Each side of the B11/2 sensor (each pole to ground) measured 3.4Kohms. It's about 65F ambient here.
Arthur do you think we are getting close to knowing why the car doesn't go close loop? Regarding the "trick" I guess I'll do it if you think it is an important test as well. Not sure what i would be looking for.
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1972 450SL 1982 300D Turbo |
#17
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Check Sensor values with engine at normal running temp.
You seem to have correct power, etc... |
#18
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[QUOTE=Arthur Dalton;1691661]Check Sensor values with engine at normal running temp. QUOTE]
Ok but i don't think the computer is triggered to go close loop because the computer's coolant temp sensor drops in resistance. I believe it goes close loop within minutes. Always to leave for last is that the ecu is bad. Would be great to some how measure that the ecu has no signs of life with power and ground confirmed before condeming it. I took the ecu out of its case and besides some flux residue on the board (cleaned it off) i didn't see any cold solders or burnt componets or traces.
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1972 450SL 1982 300D Turbo |
#19
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With KOEO, the duty cycle should indicate the type, Federal or Calif, or bad ECU. Tell us what it says. I also think a bad ground could cause a similar problem.
My 420SEL has a similar problem and I have a replacement ECU to install. I replaced the O2 sensor as well.
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Regards Warren Currently 1965 220Sb, 2002 FORD Crown Vic Police Interceptor Had 1965 220SEb, 1967 230S, 280SE 4.5, 300SE (W126), 420SEL ENTER > = (HP RPN) Not part of the in-crowd since 1952. |
#20
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Quote:
Please note, my MIL comes on for 3 seconds with KOEO, does that mean the CIS computer is working?
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1972 450SL 1982 300D Turbo |
#21
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[QUOTE=erubin;1691975]
Quote:
Here is a Tech Quote from some info I have.... < acceleration enrichment were built in. With this bending bar that is controlled by current flow, all of a sudden we have a very fast acting metering device. If we put an oxygen sensor in the exhaust stream and plug it into the computer that controls the pressure differential in the fuel distributor by bending the bar in the EHA, we have a quick feed- back system. This is called Closed Loop. The oxygen sensor controls the current flow to the EHA via the CIS-E computer. When a temperature switch tells the computer the engine is about 70C, the injection system switches from it's fixed cold operating parameters (open loop) into closed loop and the only determinant for injected quantity is the oxygen sensor. >> Regardless..if you have already checked the 02 senors output and heater and it is responding to manual mixture inputs, then the mimic technique I mention was just to verify that input to the ECU... Have you tried @ 2K rpm ? |
#22
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I measured the temp sensor at pin 21 on the CIS connector. The resistance goes down as expected and resistance is to specification as engine warms up. That is not the problem. Car always runs open loop.
Next I started the car with the CIS disconnected and car started and ran the same as when connected! Also the MIL simply times out after 3 seconds with KOEO whether or not the CIS is connected! So that is not proof of a good ECU. With the CIS connected i disconnected the O2 sensor and ran the car, and no MIL! car remains in open loop at all engine speeds including 2000rpm.
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1972 450SL 1982 300D Turbo |
#23
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You have verified 02 sensor heater circuit for cont. and 12v power ?
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#24
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The O2 sensor heater does not get controlled by the ECU (CIS) so it shouldn't make a difference even if the heater circuit was out. I can confirm that the sensor gets plenty hot quick and moves up and down between .1 and .9V when I artificially lean/enrichen. But no feedback current from the computer to start trimming the EHA.
I don't believe the CIS stops functioning if the heater circuit was a problem. If you believe otherwise I'll pull the carpets out and probe it.
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1972 450SL 1982 300D Turbo |
#25
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I think you may be correct , so don't bother.
My concern on the heater was 02 cross count input to N3. Which is why I mentioned the bat mimic test to get cross counts input to see if EHA ma reading responded to an input to ECU.. |
#26
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Quote:
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1972 450SL 1982 300D Turbo |
#27
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