EGR valve diagnosis

Tiny
SZALKUSKT
  • MEMBER
  • 1993 TOYOTA CAMRY
  • 2.2L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 116,000 MILES
I have a 93 Camry 2.2L and I want to troubleshoot the EGR valve system. I know there a re a few compoents. I believe that the EGR is intemittently opening at idle and while on highway. I get bucking and chugging on th ehighway and bad idle and sometimes stall out at idle. No check engine lights. I want to trouble shoot the EGR valve, modulator, ported vacuum valve and I think there is a solenoid in the system in back under the intake. I want to trouble shoot before I take EGR off to clean. Basically I am trying to rule out my EGR system as I did an inspection of the ignition system and checked for major vacuum leaks by spraying carb cleaner on areas.
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Monday, February 1st, 2021 AT 11:12 PM

20 Replies

Tiny
KASEKENNY
  • EXPERT
This does sound like an EGR issue so here are the tests and inspection of the system. Please see below for the detail. Check out the diagrams (Below). Let us know what happens and please upload pictures or videos of the problem.
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Monday, March 1st, 2021 AT 5:20 PM
Tiny
SZALKUSKT
  • MEMBER
I checked the EGR valve and applied vacuum and the engine stumbled and almost shuts off. Therefore, I feel the EGR valve is okay. I performed the steps 1-6 and at 2500 cold with the jumper installed, I got zero vacuum. At 2500 with engine at normal operating temperature, the vacuum did not respond abruptly while reaching 2,500 RPMs, but it slowly increased only to 3-4 inches Hg. I did not feel that I saw a definite reaction at 2,500, but a slow increase after reaching 2,500. While I was doing all of this, I removed the old modulator and compared it to a brand new one that I bought and the large port that is on the bottom of the modulator would not hold a vacuum while the new part would, so I deemed the old modulator bad and installed the new one. I took the car for a test run and it did not stumble at idle, but it still performed sloppy on the highway. Since the only other component is the VSV under the intake on the rear of the engine, I feel that I should replace the VSV. Steps 7-9 seemed a little unclear to me, but since I put a new modulator in and deemed the EGR valve itself okay, I feel that the VSV is not performing as it should. Any suggestions?
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Monday, March 8th, 2021 AT 7:05 PM
Tiny
KASEKENNY
  • EXPERT
It is rare on these posts that I don't have suggestions but I agree 100% with what you did. If it were me, I would replace it based on this. Excellent update. Please let us know what happens. Thanks
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Tuesday, March 9th, 2021 AT 5:50 PM
Tiny
SZALKUSKT
  • MEMBER
I put a vacuum/pressure gauge on the hose from the side of the EGR to the bottom of the modulator, and I feel pressure, but see only a flutter on the pressure gauge. The flutter does not even register 1 PSI. The backpressure in that hose to the modulator is something I cannot say for certain if it is acceptable. It seems as though this pressure to the bottom port of the modulator should be smoother. I took the old modulator apart and examined the diaphragm. It had a tear in it. I took pictures and will try post them tomorrow. I think my question right now is, does the VSV remain energized at all times when the engine is at operating temperature and only allows the vacuum to flow through from port Q of the modulator to the top port of EGR valve diaphragm? I just can't figure out why there are still drivability issues with a seemingly good EGR and a brand new modulator.
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Wednesday, March 10th, 2021 AT 12:33 AM
Tiny
KASEKENNY
  • EXPERT
It does not remain on all the times. The ECM switches it when it is needed.

I attached the detail below from the manual. It is not a lot of info but gives what I think you are looking for.
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Wednesday, March 10th, 2021 AT 6:04 PM
Tiny
SZALKUSKT
  • MEMBER
I have a new VSV and I am planning to change it. I just feel that the exhaust back pressure to the modulator is not enough. Have there been cases where the supply of exhaust pressure to the bottom of the modulator is not enough (from the port on side of EGR valve)? I am wondering what good pressure would be when I rev the engine with a pressure gauge on it. I could not get above 1 psi on my test. Could the EGR be clogged at the supply port for exhaust to the bottom of the modulator? I am still going to change the VSV since it is original. I have some pictures to share. I have a picture of new modulator on car, new modulator diaphragm holding vacuum (even though it works off of pressure), top of old modulator showing ports, inside of old modulator torn, in half, and carbon inside with water (not sure how moisture got inside there but there was).
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Thursday, March 11th, 2021 AT 12:09 AM
Tiny
KASEKENNY
  • EXPERT
It is hard to know for sure only because I am not sure what it should be on this set up but based on those pictures, if they have that much soot and build up then the EGR is similar or worse. I would at least remove it and check the inlet shown below. You can clean them using a chemical like CRC cleaner but I would just replace it if it has soot on it.
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Thursday, March 11th, 2021 AT 6:27 PM
Tiny
SZALKUSKT
  • MEMBER
What type of CRC cleaner would you use? There are different ones.
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Friday, March 12th, 2021 AT 12:32 AM
Tiny
KASEKENNY
  • EXPERT
I use the throttle body/intake cleaner. There are others but I have not had any issues with this one. Some of them like the brake parts cleaner is too aggressive and I worry it will damage the valve even through it would probably be fine.
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Friday, March 12th, 2021 AT 4:55 PM
Tiny
SZALKUSKT
  • MEMBER
I changed the VSV and it seems that the car is about 95% better. I took it for a test run after and then a normal day of driving to and from work. The idle stumbling problem appears to have vanished and there is a slightly noticeable chug on the highway when releasing the pedal and coasting at highway speeds and throttling back to highway speed. However, I still have a problem with the connector to the VSV itself. The connector will not "clip" onto the VSV because the plastic is brittle and the clip broke. I want to buy a connector and extract the pins and replace the connector on the wiring harness without cutting the existing wires from the engine harness. I just want to replace the plastic connector. There is a slight oil leak from the engine and over time the oil gets into the connector if it is not sealed. I have a picture of the old VSV and a high Ohm reading. The new part read about 37 ohms while the old part was over 200 ohms. Take a look and let me know what I can do with the connector. Can I buy the connector from Toyota and remove the pin and wires from the old connector and replace it into a new connector?
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Wednesday, March 17th, 2021 AT 11:51 PM
Tiny
KASEKENNY
  • EXPERT
That is a great find with the resistance. You can get the connectors if the dealer has them available but if I can make a suggestion, I would find the pigtail which is the connector and the terminals with about 10 inches of wiring. Then I would cut the wires and solder the new ones in place. The only reason I suggest this is the weakest and most important part of a connector are the terminal ends. Basically the female part of the connection can get spread and not make good contact. So if you are going to replace it, I would replace the entire connector with the terminals and wires.

Picture below but you need to solder them, don't use those butt connectors. They are junk and fail all the time.
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Thursday, March 18th, 2021 AT 6:56 PM
Tiny
SZALKUSKT
  • MEMBER
Okay. Thanks for the information! I think I will try the dealer for a nice pigtail with wires. I am coming up with not much on searching elsewhere. Any ideas? I think the only things I have left to perfect the EGR system would be to clean the EGR with CRC as you suggested already and solder a new pigtail on the VSV because I am still getting a slight chugging at highway speeds when releasing the throttle and taking foot off the pedal. Have not experienced any idle problems so far with everything connected.
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Thursday, March 18th, 2021 AT 9:54 PM
Tiny
DL AUTOSHOP
  • MEMBER
Hello, I'm Danny.

Just here to add my 2 cents. Are you going to clean and re-use the old EGR valve or install a new one? Also just be sure when installing a new replacement EGR harness-pigtail to be sure to use one from the dealership. It's real easy to get a cheap knockoff replacement from your local auto parts stores but what you need to understand is the EGR valve being a part of the exhaust system makes it subject to high temperatures being a part of the exhaust cycle. With that being said it needs to be a factory weather pack connecter for that to be heat-resistant, completely sealed, tight fitting, and long lasting. Hope this helps and thanks again for using 2CarPros.
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Friday, March 19th, 2021 AT 6:21 AM
Tiny
SZALKUSKT
  • MEMBER
I was planning to remove the existing EGR valve and inspect it and clean it since it costs about $150.00. I will make a decision to keep it or replace it once I remove it and inspect it since it is operating okay. As far as the pigtail, it goes on the VSV which is only subject to the heat of the engine block because it is mounted to the back of the engine on the intake manifold and not directly to the EGR valve itself. I understand how the EGR valve and piping can be hotter. Thanks for your input. I will try to go to the dealer and see if the have the weather pack connector/pigtail. I agree that a genuine part would work best for sure as far as fitment and durability. I agree with you! Thanks, Danny! It will be hard to solder it given the location of the VSV valve, but I'll try.
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Saturday, March 20th, 2021 AT 10:51 AM
Tiny
SZALKUSKT
  • MEMBER
I went to the dealer after asking if they sold a "pigtail" with the wires already inserted into the connector and they said no. Therefore, I found the 5 digit number on the connector which was 11156. The parts guy used this to find the connector shown in the picture. I plan on removing and re inserting the existing wires into the new connector since the brittle plastic of the old connector is my main concern right now and Toyota only has the wires with terminals already crimped for $31.00 each! I want to see how using the existing wires works with a new OEM Genuine Toyota connector. I have pics of the new connector and the old connector where you can see the 5 digit number slightly. Enjoy the pics!
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Sunday, March 21st, 2021 AT 2:53 PM
Tiny
DL AUTOSHOP
  • MEMBER
Hello again.

Thanks for the pictures. Keep us updated on the repair. Thanks again for using 2CarPros.

Danny-
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Sunday, March 21st, 2021 AT 8:55 PM
Tiny
SZALKUSKT
  • MEMBER
A little update: I am still experiencing chugging on the highway. This happens when I am at highway speeds and I open the throttle slightly off the closed position back and forth when I need to coast if the car in front of me is going slower and I need to slow down. Therefore, I still feel that the modulator and the VSV may have been a contributing factor in the problem, but since when I pull the vacuum hose off of the EGR valve, the problem goes away. So, I feel the EGR is the problem in a way and I need to remove it and clean it even though it causes the car to die when a vacuum is placed on the diaphragm to check it. I have replaced or inspected everything else other than replacing the connector to the VSV. So, I need to clean the EGR and change the VSV connector. I will update you after I do these things.
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Saturday, March 27th, 2021 AT 12:29 PM
Tiny
DL AUTOSHOP
  • MEMBER
Hello again.

Excessive carbon build-up on the assembly can cause the EGR needle to stick and not function properly. Let us know what happens after you repair. Hope this helps and thanks again for using 2CarPros.

Danny-
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Saturday, March 27th, 2021 AT 3:07 PM
Tiny
SZALKUSKT
  • MEMBER
I have changed the connector to the VSV, and still experience the same chugging. I will have to remove the EGR valve itself and clean it or replace it. Then I will test it again. Removing and either cleaning or replacing the EGR itself is the only thing I have not done so far. When I find time to do the EGR valve itself I will update everyone. Right now I have the EGR vacuum hose to the EGR valve disconnected and the car runs fine. However, I want to have the system working properly. So, I will have to remove the EGR and either clean or replace the EGR valve assembly.
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Sunday, June 6th, 2021 AT 3:18 PM
Tiny
DL AUTOSHOP
  • MEMBER
Hello again.

Okay, keep us updated after cleaning or replacing the EGR valve to see if this remedies the problem. Thanks again for using 2CarPros.

Danny-
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Sunday, June 6th, 2021 AT 5:40 PM

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