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What tells EGR valve to operate?

  #1  
Old 11-30-2008, 07:12 PM
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Default What tells EGR valve to operate?

I have a stock 2005 Lancer ES with the little motor. The vacuum operated EGR valve is clean and opens when tested with a vacuum.
It bolts to what looks like 6 or 7 inches of manifold. Is the EGR port inside the manifold just past the throttle body or is it down where the EGR valve bolts on?
What triggers the vacuum to operate the valve?
If the valve operates and the port is clean, I would need to test the sensor that triggers the operation of the vacuum.
Thanks you for answering my questions.
 
  #2  
Old 12-03-2008, 07:07 AM
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Default RE: What tells EGR valve to operate?

So what is your problem...are you getting some kinda error code? An EGR valve is driven strickly on vacuum. So there isnt any electrical sensors that control it. The electronics to it are strickly for monitoring purposed. The valve itsself should be external of the manifold right where it bolts on. Typically if there is a problem with the EGR system you may have either a clog in it (which you stated is fine) or the vacuum lines are incorrectly run or are leaking causing the EGR valve not to function correctly
 
  #3  
Old 12-03-2008, 05:19 PM
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Default RE: What tells EGR valve to operate?

ORIGINAL: TheEngineer

So what is your problem...are you getting some kinda error code? An EGR valve is driven strickly on vacuum. So there isnt any electrical sensors that control it. The electronics to it are strickly for monitoring purposed. The valve itsself should be external of the manifold right where it bolts on. Typically if there is a problem with the EGR system you may have either a clog in it (which you stated is fine) or the vacuum lines are incorrectly run or are leaking causing the EGR valve not to function correctly
Yes. A code.
I removed the valve and cleaned it. If I operate the valve manually at idle, it cause the engine to run rough and want to stall. I am assuming that from this the valve operates and the port is clean. Right?
The valve is vacuum operated but what keeps it closed at idle and opens it at speed? Purely vacuum from the intake manifold? I chased the vacuum lines to the EGR and they were not clogged. One of them has a restrictor in it. I could get air to go one way but not the other. I am positive that I put the vacuum lines back correctly. I was getting the code before I removed them anyway.
There is an EGR vacuum regulator solenoid valve that receives signals from the ECM or PCMthat receive signals from the Volume Airflow sensor, the ECT sensor and the Crankshaft position sensor.
I am assuming that since I have no other problems but the code for the EGR that the ECT and crankshaft position sensors are working normally.
I am suspecting the Volume airflow sensor may be involved along with the EGR vacuum regulator solenoid.

By the way. Thanks for the reply. As you can tell, I have done some more research since the first post. This is aggravating.
 
  #4  
Old 12-03-2008, 05:47 PM
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Default RE: What tells EGR valve to operate?

#12421Q is the solenoid and it switches the vacuum on and off to the EGR
#12431 is a vacuum control in between the solenoid and the EGR both parts are commonly replaced for an EGR code repair. search part numbers MR127520 solenoid and MR126976 control on my site for pricing
 
  #5  
Old 12-03-2008, 06:07 PM
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Default RE: What tells EGR valve to operate?

Link to your site?
 
  #6  
Old 12-04-2008, 06:56 AM
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Default RE: What tells EGR valve to operate?

  #7  
Old 12-05-2008, 08:07 PM
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Default RE: What tells EGR valve to operate?

There should be an egr solenoid that gets source vacuum all the time and when commanded by the pcm will apply vacuum to the egr valve. I would look into that dirction. Check for any broken/cracked vacuum lines.

T bone, the way you tested the egr valve tells you that the ports on the egr valve are not clogged and its operating correctly.
 
  #8  
Old 12-06-2008, 06:56 AM
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Default RE: What tells EGR valve to operate?

ORIGINAL: dsm1990gsx

There should be an egr solenoid that gets source vacuum all the time and when commanded by the pcm will apply vacuum to the egr valve. I would look into that dirction. Check for any broken/cracked vacuum lines.

T bone, the way you tested the egr valve tells you that the ports on the egr valve are not clogged and its operating correctly.
Thanks for the reply.
Yes, I intend to get a vacuum tester today and check some inches of vacuum. If I find nothing, then I suppose I will be getting a manual vacuum pump and testing the egr vacuum regulator solenoid. I've always wanted some of those anyway and it will keep me from needlessly buying parts on this and other vehicles.
I found some information on the ohms and voltage for the solenoid also and if the vacuum checks out I will be using the volt/ohm meter to isolate that. I already have a meter.
 
  #9  
Old 12-06-2008, 07:05 PM
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Default RE: What tells EGR valve to operate?

Well, today I connected the vacuum gauge to a tee in the line to the EGR valve. The engine was hot and was supposed to have 3.9 in. Hg when the engine was revved up. The reading was 0. This means that the EGR was not operating when it was supposed to.

I connected a vacuum line directly to the EGR valve and pulled a vacuum on it at idle. The engine tried to die. This means that the EGR valve and port are passing exhaust gas to the intake.

I connected the gauge to the vacuum control valve and plugged the end of the EGR connection. The vacuum is supposed to read between 6.3 and 7.1 in. of Hg. It was about 6.5. The vacuum control valve is operating correctly.

I connected the gauge to the throttle body EGR vacuum nipple. It is supposed to reach 15 in. of Hg. It did. It reached this level in less than a second each time I connected the gauge like it is supposed to do.

I couldn't get to the EGR vacuum regulator solenoid valve to apply voltage to the pin connections from the battery and see if the vacuum leaked down or not.

I did measure the resistance between the pins on the EGR vacuum regulator solenoid valve and it was within the tolerance of 29-35 ohms.

Then I tried to take the EGR vacuum regulator solenoid valve off the machine to perform the direct voltage test.

HOLY COW. This is almost impossible. The boltis buried between the intake manifold and the engine in the most difficult place to reach that I have ever seen since I've been working on automobiles for the last 40 years.

The solenoid is bolted to a plate that is bolted to the intake manifold. It is impossible to reach this nut. The plate is held onto the intake manifold by 4 bolts. 3 of these are almost impossible to get to. I started into it and could get a socket on one bolt and holding a 10 mm wrench in two fingers could just reach the other 3 laying on the engine and bracing my feet on the ceiling.

I gave up. I guess I'll emit nitrous oxide into the atmosphere until I get rid of the beast.

I hate engineers. I guarantee you they have never turned a wrench on one machine.
 
  #10  
Old 12-10-2008, 10:28 AM
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Default RE: What tells EGR valve to operate?

So, does anyone have a trick to getting that solenoid off of that plate between the intake manifold plenum and the engine block besides pulling the intake plenum?
 

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