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.

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

RE: What tells EGR valve to operate?
 

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.

RE: What tells EGR valve to operate?
 

http://i35.tinypic.com/20gfpxc.jpg#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 :)

RE: What tells EGR valve to operate?
 

Link to your site?

RE: What tells EGR valve to operate?
 

mitsupartsman.com

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.

RE: What tells EGR valve to operate?
 

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.

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.

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?

RE: What tells EGR valve to operate?
 

remove the whole plate first #12421a

RE: What tells EGR valve to operate?
 

Tried that. Can't get a wrench on 3 of the bolts much less a socket.

RE: What tells EGR valve to operate?
 

Well the saga continues.

Today I manufactured some wires to plug into the EGR vacuum regulator solenoid valve to apply 12 volts directly from the battery and pulled a vacuum on the correct nipple on the solenoid.

With voltage applied the vacuum held. When the voltage was removed the vacuum leaked down.

This is positive evidence that the solenoid works. I could hear it clicking when the voltage was applied and removed.

Okay. This means that the 12 volts is not being removed to allow vacuum to be applied to the EGR valve.

That leads to the three sensors that tell the PCM to cycle the ground that removes the 12 volts from the solenoid and allows vacuum to go to the EGR.
Mass Airflow Sensor
Crankshaft Position Sensor
Engine Temperature Sensor

I don't think that the Crankshaft Position Sensor could be bad. I think there would be other problems.
I don't think the Engine Temperature Sensor is bad. No codes and I think there would Lean Adaptive limit codes. (I've seen this before)
The Mass Airflow Sensor could be bad or sending bad signals. You need an oscilloscope to check this one because the signal is in ascending pulses measured in cycles per second.

I could buy a $5,000 diagnostics machine or I could save my money and trade for a Chevy truck at an $8,000 discount.

RE: What tells EGR valve to operate?
 

You could always bite the bullet and take it to satan.

RE: What tells EGR valve to operate?
 

No. I've been meaning to learn this crap for years now and I figure I may as well startnow. Stupid democrats and EPA. Billions of cows put out millions of tons more emissions than a 1965 Chevy with a carburator and points. Simple. Fuel, fire, compressionand timing.
Rant over.

I have yet to bring a vehicle to a mechanic much less a dealer other than warranty work and I'm not going to start now.

RE: What tells EGR valve to operate?
 

Is your check engine light coming on, are you getting p0401?

RE: What tells EGR valve to operate?
 

Yep. P401 and after I work on it P403 because I will start it with something unplugged. Once cleared, the P401 comes back.

RE: What tells EGR valve to operate?
 

Measure the resistance between the terminals of the EGR solenoid. Standard value: 29 - 35 Ω [at 20°C (68°F)] 6.Replace the solenoid if resistance is out of specification

did you try this?

RE: What tells EGR valve to operate?
 

2.With the temperature sensing portion of engine coolant temperature sensor immersed in hot water, check the resistance. Standard value: 14 - 17 kΩ [at -20°C (-4°F)] 5.1 - 6.5 kΩ [at 0°C (32°F)] 2.1 - 2.7 kΩ [at 20°C (68°F)] 0.9 - 1.3 kΩ [at 40°C (104°F)] 0.48 - 0.68 kΩ [at 60°C (140°F)] 0.26 - 0.36 kΩ [at 80°C (176°F)] 3.If resistance deviates from the standard value greatly, replace the sensor.

RE: What tells EGR valve to operate?
 

6
EGR vacuum regulator solenoid valve
Ignition switch: "ON"
B+

Engine: idling Suddenly depress the accelerator pedal.
From B+, momentarily drops
voltages from terminal #6 of the pcm to your solenoid.
this should keep you busy for a while......lol

RE: What tells EGR valve to operate?
 

Well I was looking at all data and if you have the 2.0 I would really look into the manifold differential pressure sensor. Ford has something similar to that and its called a dpfe sensor. Also on fords I see a lot of p0401 and as long as the egr passage is clean, I'll replace the dpfe sensor and that usually fixes the dtc.

RE: What tells EGR valve to operate?
 

Sorry for the delay. I looked into a troubleshooting manual and wound up at the same place. The manifold pressure differerntial sensor. I'm going to locate this sensor and try to see if it might be dirty or something.

RE: What tells EGR valve to operate?
 

if you were to trigger the solenoid to open the egr you can check the fluctuation voltage of the mdp. if the mdp was the problem, why would it not throw a mdp code too?

RE: What tells EGR valve to operate?
 

Good question. No code there. I didn't trigger the solenoid with the motor running, though. I could only trigger it with the harness unplugged from the solenoid so as to apply and then remove the battery positive voltage. I could hear the solenoid actuating. I am pretty sure that the PCM is not removing the 12 volts from the solenoid to actuate it. 12v battery positive holds the solenoid closed and it is available in the plug.

There's a few troubleshooting tips for the MDP to check voltage at the back of the plug. If it doesn't change when the engine is revved, then it might be defective. I will eliminate this first.
Then on to the ECT sensor.

RE: What tells EGR valve to operate?
 

Well, I fixed it.

Today I traded the Lancer in on a 2008 Chevy 1500 Single Cab W/T 4WD.

The check engineer light is temporarily fixed until the next one.

RE: What tells EGR valve to operate?
 

Haha well thats one way to fix the cel.

RE: What tells EGR valve to operate?
 

this was like getting hooked on a tv show and just when you think you'll find out who shot JR the season ends:(

to be continued next year on the chevy forum....lol

good luck to you.

RE: What tells EGR valve to operate?
 

Sorry. The trade had nothing to do with the CEL. It was opportunity knocks. 7,000 dollars off on the selling price of the truck. I couldn't resist. I've always wanted a 4WD Chevy. I was really interested in finding the problem. As you can tell, I'm persistant if not too smart.

Thanks for the help, regardless. Good luck to you all in the future. See you at the Chevy forum.