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  #16  
Old 12-02-2007, 03:21 PM
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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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  #17  
Old 12-02-2007, 04:34 PM
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Check Sensor values with engine at normal running temp.
You seem to have correct power, etc...
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  #18  
Old 12-02-2007, 10:28 PM
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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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  #19  
Old 12-03-2007, 12:53 AM
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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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  #20  
Old 12-03-2007, 01:22 AM
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Quote:
Originally Posted by wbain5280 View Post
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.
I measure nothing on pin 3 of the round 8 pin diagnostic connector (driver side). I measured it in Duty Cycle, Frequency and AC voltage but it always said 0. Measured between pin 3 and engine ground as well as between pin 3 and 2. Does that mean the computer is dead (it is getting power and ground).

Please note, my MIL comes on for 3 seconds with KOEO, does that mean the CIS computer is working?
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  #21  
Old 12-03-2007, 11:56 AM
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[QUOTE=erubin;1691975]
Quote:
Originally Posted by Arthur Dalton View Post
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.
I believe the temp sensor holds open loop, but I could be wrong ..

Here is a Tech Quote from some info I have....

< It is not like the old warm up regulator where only the warm up curve and
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 ?
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  #22  
Old 12-03-2007, 05:36 PM
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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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  #23  
Old 12-03-2007, 06:16 PM
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You have verified 02 sensor heater circuit for cont. and 12v power ?
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  #24  
Old 12-03-2007, 10:41 PM
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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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  #25  
Old 12-04-2007, 12:46 AM
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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..
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  #26  
Old 12-04-2007, 01:46 AM
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Quote:
Originally Posted by erubin View Post
1989 260E Federal.
Car never goes into closed loop. No current through the EHA and O2 sensor does not oscillate. The O2 sensor was replaced and is good. O2 voltage moves up and down when I create a forced lean or rich condition. EHA shows 20ohms which is good. No duty cycle or frequency measured off of pin 3 of diag connector.
- I have a good OVP (fuses good too). Also checked with test lamp that the CIS is getting good power and ground.
- The check engine light comes on for 3 seconds as is normal during KOEO.
- I opened up the CIS case and nothing smells burnt, no cold solders and no obvious burnt components or traces.
- O2 signal is getting to the CIS computer but no closed loop (feedback) operation.
- With KOEO the O2 signal is 0V and it should be .4-.5V.

Please help.
I don't even get current through the EHA with KOEO (spec is 20mA). Same no current with engine running. My first thoughts were a burnt out EHA but it ohms out to 20ohms. I also get no signal (V, freq or duty cycle) off of pin 3 of the diagnostic round connector.
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  #27  
Old 12-04-2007, 02:26 AM
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http://www.continentalimports.com/ser_ic20134.html

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