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So Been Getting the Check Engine Light and the Misfire and P0401

Replaced
02 Sensors
TPS
6 Coil Packs
EGR Valve

Cleaned
Mass airflow Sensor
EGR Tube

I am still getting those damn codes and I am at my wits end... It also Has a high pitched wine and idle problems...
 

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Interesting! You have a misfire and no CEL for that? When you say you cleaned the "EGR tube".......are you talking the EGR tube on the inside of the intake or the tube from the exhaust manifold to the EGR? Pull the EGR and look at it. If there is some water condensation in there, you still have a blockage. I used a Greenlee electrical wire fish to clean out the EGR tube running thru my intake and my P0401 code is gone. As for the misfire, lots of possibilities there. Have you checked the compression on all 6 cylinders? (Just to go ahead and rule that out)
 

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Clear the codes and see what comes back. Ck for img leak. good luck,tony
 

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The ECM periodically tests the EGR valve by commanding it open and monitoring the Manifold Absolute Pressure (MAP) sensor for an expected drop in pressure. If it does not see the expected change it sets DTC P0401. Since you have changed the valve and cleaned the tube there could be problem with manifold pressure. Your complaint of poor idle and a high pitch whine could be the result of a leak in the lower intake manifold gasket.
 

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A blocked EGR also effects idle. Are you certain the tube is clear all the way thru? Blow air through it to test. Like i said earlier, if you have any condensation on the bottom of the EGR, you still have a blockage.
 

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I agree with Buster. You probably have a lower intake leak and spent a crap load of money dancing around it.
 

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put a vacuum gauge on it and see what's going on.
 

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i was getting the same code i changed all the plugs with denzos. miss fires on the 3.2 will mess up the cats. try unpluging the egr valve and see how it runs. also check the vacume line that is hooked onto the fuel pressure regulator. mine was cracked and pretty much fell off when i touched it.
 

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when i said unplug the egr. i ment unplug the wire... and see how it run. mine runs good with the wire unpluged. im not sure whats going on. it misses/surges at around 2500rpm. but will not put out any codes. ill unplug the wire to the egr and the surging at 2500 goes away. im thinking that my cats may be cloged and its causeing to much back pressure through the egr. ie into the manafold. or the egr is sticking open but i get no codes saying that it is. im haveing the back pressure in front of the cats checked monday. if there clogged im haveing them replaced. i will update whats found. also there is a TSB about miss fires causeing damage to the cats.. also number 6 coil is difrent from the rest of the coils..
 

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Intermittent stumbles while driving around town, Stalling from time to time.

No Codes.

Oh! I hate Intermittents!

A vacuum test confirmed loss of Intake manifold vacuum when the engine miss showed up.

EGR removed for inspection. The pintle would stick open when in the full open position.

Cleaned with kerosene, rotating the pintle, as well as moving open and closed.

Lubed with "Dry Slide" Moly. Installed with new gasket ($2.11)

The miss hesitation and stalling is gone...

For today ;-)
 

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I have the same problem. Of course mine is in the middle of a mid-life crisis.

I'd check the fuel delivery(i.e Fuel Pressure), air (i.e Intake Manifold Gaskets upper and lower) and spark plugs.
 

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my scanner is showing bank 2 fuel trim at 22.0 and bank 1 fuel trim at 5.0 bank 2 is way to lean.. check for vacume leaks i didnt find any. replaced o2 sensor bank 2 up stream. cleaned MAF, EGR and tube are working 100% all sensors seem to be working as they should. im getting no check engine light or codes. bank 2 being so lean is making the engine surge at around 2300rpm's i have no idea whats going on with this thing. new plugs installed. denzos.. could a bad cat cause this? LOST!
 

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How's the fuel pressure looking? Also, you might want to have the ECU checked out.

Your CAT suggestions also checks out, as it may be blocked out. But how does one do that? I'm faced with the same issue.
 

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Swap it with a known good one?

There is no "procedure" that I have ever come across.
 

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to check to see if the cat is clogged take it to a shop or if you have your own gauge to check back pressure they will drill a small hole 1/4 in the pipe before the cat and check the pressure at the front the cat. if its high its clogged. if its not clogged they will let it on the car and plug the hole. fuel pressure should be between 43-55 psi.
 

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bigstick1973 said:
to check to see if the cat is clogged take it to a shop or if you have your own gauge to check back pressure they will drill a small hole 1/4 in the pipe before the cat and check the pressure at the front the cat. if its high its clogged. if its not clogged they will let it on the car and plug the hole. fuel pressure should be between 43-55 psi.
NICE!
 

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On another note, I noticed how we both replaced our spark plugs with Denso's. I did mine somewhere in November last year. Could it be the plugs?
 

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I really don't think its the plugs. Have you have you put your on a scanner and viewed the live data. I can see mine is running leanon my scanner. The fuel trim is reading 22.0 on my drivers side witch is bank 2. I pulled the plugs and the white witch would also show a lean bank. The o2 sensors wile in closed loop will set the fuel trim. The o2 sensor on bank 2 is saying bank 2 is rich and so its going lean to ajust for this. The problem is its really not rich. Iv replaced the o2 sensor and still get the same trim reading. so I'm guessing the cat is clogged and is backing up causing a false rich. Shop is checking the back pressure tomorrow. Will updat!
 

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I unfortunately don't have a scanner to see the live data. All I have is ODBII code reader. I'd like to know what is happening with yours.
 
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