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Code 154 ? 850

posted by B.B. on Sun Sep 26 11:35 CST 2010
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last visit: Mon Oct 6 13:15 CST 2014

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After clearing the ECU codes on Friday afternoon, a day later I get
code 154

Leaking EGR valve
signal to EGR controller faulty
EGR controller faulty
Poor ground
Engine thermostat faulty

I just cleaned the EGR valve again
The engine is idling rough
The thermostat seems normal

*where is the EGR controller?
*Where does the EGR controller signal come from?
*Where is the ground in this circuit?

Thanks, Bill

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Code 154- Fixed 850

posted by B.B. on Thu Sep 30 06:07 CST 2010
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last visit: Mon Oct 6 13:15 CST 2014

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Thanks to Icelandic for the clue to check for switched vacuum lines at the EGR
controller.
The car is behaving great finally, and the around town mileage went from 10 to 21.

The codes were a reaction to an intermittant vacuum loss caused by
incorrect vacuum line routing to the egr controller. So it was hard to
find the leak since it was being switched on and off.

Bill

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Code 154 ? 850

posted by Icelandic on Sun Sep 26 13:52 CST 2010
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last visit: Tue May 8 06:35 CST 2012

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It happened in my 1995 850 NA a few months ago. After cleaning the EGR, I noticed that idle was not steady but had very small oscilations. I found out that egr was not closing properly due to wear. Perhaps cleaning it removed deposits in the sealing area of the valve and it was unable to close properly. Thus I was having constant flow of exhaust gas thru it thus causing the funny idle. I had to replace the valve.The EGR should not open during idle, only under load at certain rpms. The controller is at the radiator shroud. It is a cylindrical thing with an electric connetor and two vacumm hoses: one coming from the vacumm three and the other going to the egr.

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EGR valve and/or EGR controller 850

posted by B.B. on Mon Sep 27 02:21 CST 2010
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last visit: Mon Oct 6 13:15 CST 2014

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Thanks for the info,
The EGR valve seemed to seal up OK when I had it out,
It looks like a good idea to check the controller which just looks
like a vacuum switch, maybe that can fail to close as well,
and keep the EGR open?

Bill

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EGR valve and/or EGR controller 850

posted by Icelandic on Mon Sep 27 02:55 CST 2010
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last visit: Tue May 8 06:35 CST 2012

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Tha controller can certainly fail, but I have never heard of one failing on the posts. Check the two vacumm lines, and see if they are not reversed on the controller. In my car, looking from the top, you can see two vacumm lines leaving the controller. The yellow one is in the upper port and a beige is on the lower one. From what I know, under certain conditions the ECU sends a signal to the controller and it opens letting vacumm activate the EGR (opens it)letting a portion of exhaust gas into the intake. Under idle it should be closed full time. If you get the 154 code that means exhaust gas in passing thru when it shouldn´t and that is picked up by the temperature sensor in the egr body. Besides the vacumm lines, check the connector on the controller and for good measure the connector on the egr temperature sensor. When you cleaned the egr, did you check if the internals were moving freely by applying vacumm to it? Are you sure there is not some piece of hardened gunk in there preventing it from closing?

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EGR valve and/or EGR controller 850

posted by B.B. on Mon Sep 27 03:18 CST 2010
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last visit: Mon Oct 6 13:15 CST 2014

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I just cleaned the EGR again the other day with a can of carb cleaner
and also allowed it to get a long soak. I got a good amount of grit and
some pepper size flakes out of it. I wire brushed the EGR sensor
and use dielectric silicone on all of the connectors.

I'm going now to look at the egr controller lines again.
Where do the yellow and beige lines go to from the controller?

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EGR valve and/or EGR controller 850

posted by Icelandic on Mon Sep 27 03:35 CST 2010
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last visit: Tue May 8 06:35 CST 2012

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Just checked on my car: The yellow line goes to the EGR vacumm actuator.The beige one goes to the vacumm tree on the throttle body.

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EGR valve and/or EGR controller 850

posted by B.B. on Mon Sep 27 07:48 CST 2010
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last visit: Mon Oct 6 13:15 CST 2014

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Thanks Icelandic,

I checked the function of the EGR controller and one port was closed
and another open. The open port was connected to the vacuum tree
so I switched the lines at the egr contoller, the idle smoothed right out,
I reset the code 154 and we'll see if it stays off now.

I wonder if there's a theory write-up of the EGR system?

Does that sound right, that with no power applied, one egr controller port
is open and the other closed?

Bill

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EGR valve and/or EGR controller 850

posted by Icelandic on Tue Sep 28 06:29 CST 2010
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last visit: Tue May 8 06:35 CST 2012

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How´s it going? Trouble fixed?

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Maybe fixed. 850

posted by B.B. on Tue Sep 28 12:05 CST 2010
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last visit: Mon Oct 6 13:15 CST 2014

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The vacuum line from the egr controller to the vacuum tree
was open to dump vacuum all the time it seems.
I swapped the vacuum lines at the EGR controller and things seem
better, better smooth idle, no more funky braking, no more throwing codes.

I noticed today that on the highway the engine seemed to have lost the pickup
at highway speeds, seemed to be a lack of passing power at 60.
so maybe there's still a problem at the controller.
I'm watching: The around town mileage was ratty and see if that improves.

Bill

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Maybe fixed. 850

posted by KlausC on Thu Sep 30 16:42 CST 2010
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last visit: Fri Oct 24 10:15 CST 2014

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Now that the vacuum line is attached, the fuel pressure will not be abnormally high at idle, your plugs will clean themselves from the overrich condition, and the brake booster has more vacuum to work.

Just drive it a while and let the computer adjust to normal driving. After a tank of gas, try throttle up at 60mph. It should down shift and go.

Klaus
--
Always willing to listen, just not able to take direction.

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EGR valve and/or EGR controller 850

posted by Icelandic on Mon Sep 27 08:07 CST 2010
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last visit: Tue May 8 06:35 CST 2012

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Yes it sounds right. With power off the controller should not let vacumm thru.
Only when the ECU tells it to do so (under load at certain rpms). Perhaps when you took egr out for clean up, you mixed up the vacum hoses. I hope you have solved the problem.

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