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  #1  
Old 07-10-2004, 06:52 PM
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KE-Jetronic HELP!

I have a 1990 300e California model. Here is the long sad story. Maybe one of you ace techs can point me in the right direction. I have searched and read everything I can find on this for the last 2 weeks.

I had a fuel leak from the EHA valve, my mechanic said that both the EHA and fuel distributer were leaking. I replaced both. Turns out the fuel distributor was OK, but I had already installed the rebuit one, so I left it in.

After I got done, I started getting an Check Engine light with code 17, High/Low O2 sensor. I replaced the O2 sensor with the 1990 Ford Mustang 302 unit. I checked the output voltage at the connector, it ran .05 to .85 volts. I was still getting the CEL. I was also intermittantly getting the ABS light, so as the result of some research, I replaced the OCP relay. This solved the ABS light problem but not the code 17 CEL error. I finally got the equipment together to moitor the EHA current, the Sears DVM to monitor duty cycle, and a third to monitor O2 voltage. I wired all 3 into the cockpit so I could monitor them during driving.

With the new O2 sensor, I am at about 82% duty cycle. EHA current runs from about 1- 6ma during driving. On sudden deceleration, it goes to about -45ma, then to 0. Duty cycle fluctuates between about 80 and 83. At idle, the EHA current slowly climbs from 2-4 to about 14ma, then the duty cycle drops from 80 to 10 in about 2 seconds, then drops to 0. As soon as I give it some gas, it pops back to 80 and the EHA current drops to 2-4ma.

I unplugged the O2 voltage wire and wired a AA cell into it. The duty cycle remained about 80-82, but the EHA current went to -10ma. Car barely ran. Took the battery off, plugged the O2 sensor back in, EHA went to 2-4ma again.

The only real symptom is the CEL, still code 17. The car seems to run fine, but I get the error again after a few minutes since clearing the code. Here are some observations.

It seems to be reading the O2 sensor, as applying 1.5 v to it sent the EHA current to the opposite extreme.

O2 sensor reads .45 until it hits op temperature. Then it fluctuated between .05 and .85 in response to the throttle.

Duty cycle on the controller doesn't drop below 80%, unless it drops to 10%, then 0.

I am afraid the car will not pass emissions unless I locate the problem. Any ideas?

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Old 07-10-2004, 11:06 PM
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"At idle, the EHA current slowly climbs from 2-4 to about 14ma"


There is your check engine light.

I'm guessing you didn't set the basic piston height when you changed fuel distributers. With the fuel pump bypassed (pressure on the system) and the engine not running, how much freeplay do you have when you gently press on the airflap? You should have a distinct drop of a few millimeters to the point where the piston is engaged and fuel pressure opposes the movement. This point should also coincide with the bottom of the constant diameter section of the cone.
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Old 07-11-2004, 12:17 PM
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KE Jetronic

Steve, thanks for the reply. I measured the air flow plate just outboard of the center with the ignition ON, but the engine not running. It dropped 3.5mm before encountering resistance. The resistance happened just before the inboard side of the plate cleared the constant diameter portion of the throat.

I didn't adjust anything when I replaced the fuel distributor, or the EHA unit. As a note, the adjustment tower has been opened up, I can engage the adjustment screw with a 3mm allen wrench, but I have not moved it.
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Old 07-11-2004, 02:50 PM
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Sounds like you are alright on the basic piston height. It would be a small miracle to have two distributers in proper mixture adjustment on a switch though. Get closed loop activity around zero milliamps EHA current and then see if it is similar at 200rpms constant speed. If more than 10% different you have a problem.
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Old 07-11-2004, 07:05 PM
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KE-Jetronic

So that would be done by adjusting the 3mm screw through the top of the air cleaner into the tower, with engine hot, until it idles at an EHA current around 0, yes? Is a 1/4 turn adjustment a reasonable increment?

Would this be done at idle, or at 2000 rpm, then let it drop to idle to check. Is there a seperate idle adjustment, or is this it?
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Old 07-11-2004, 07:20 PM
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That is the whole adjustment. A quarter turn is a large mixture change, but you could easily be that far off. Take it slowly. Yes, bring the eHA current back to a closed loop cycle around 0ma. I like it actually a little rich at a -2ma center.
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Old 07-11-2004, 07:57 PM
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KE-Jetronic

I did the adjustment, took about 1/3 turn toward rich. The EHA current is now floating between +/- 1ma at both idle and 2000 RPM. However, my duty cycle is still floating between 80-82. Is this a problem if the EHA current is on?
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Old 07-11-2004, 08:46 PM
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If you have closed loop operation and no fault codes on the impulse counter diagnostic connection (should have one with a Ca car). I always look at EHA because the duty-cycle has some programmed functions and you always need to know whta its doing to understand what it says.

For instance: somewhere around 1990 on Ca cars one must enter the diagnostic mode to read proper duty cycle. Try initiating a fault code with a two second grounding of the diagnostic pin (4 I think). If you are of that system, doing this will engage the proper duty cycle you are expecting.

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