EGR flow low

[jeffromax]

The CEL came on a few month ago on my 96 camry. The car has 96K miles on it and runs perfect. I had the alarms read and reset at Autozone, the alarms were "cylinder 3 misfire" and "EGR flow low". The Haynes manual I have suggested cleaning the EGR valve which I did but eventually the CEL came back. I again had the codes read and reset, this time I got only the "EGR flow low" code. Other things I have looked at are the vacuum lines operating the EGR valve for cracks or dry rot and found none. The manual also talked about a EGR temp sensor and a VSV for the EGR vacuum system but I don't know much about how this system is supposed to work. Does anyone have any suggestions for correcting this problem?

[Erndog1369]

The VSV for the EGR is most likely not working. I have replaced many of them. It's located on the back side of the intake manifold.

[jeffromax]

Is there a way I can verify that the VSV is bad? I know it switches the vacuum to the EGR valve on and off, If you could tell me when it should be on I could put a gauge on the vacuum line to verify the proper vacuum pressure.

Thanks

[gator2764]

Originally Posted by jeffromax

Is there a way I can verify that the VSV is bad? I know it switches the vacuum to the EGR valve on and off, If you could tell me when it should be on I could put a gauge on the vacuum line to verify the proper vacuum pressure.

Thanks

Did you make sure that the ports going into the intake were cleaned out good when you removed the EGR?

[jeffromax]

No, I did not check the ports coming off of the intake for blockage. Here is a list of whatI've tried and what I found:

1. tee'd a vacuum gauge into the EGR control port, at idle it reads no vacuum, at a higher rpm, the vacuum reads anywhere from 2-5 "HG.
2. with the car at idle, connected external vacuum source to the EGR valve and at around 3-4"HG the car begins to idle roughly which indicates that the EGR valve is opening and working correctly I think
3 I ran a vacuum line directly from the intake manifold to the EGR valve, bypassing the modulator and VSV, I reset the codes and drove the car and the CEL came back on.

How does the computer know when the EGR flow is low, is there a flow sensor in this circuit? I know the EGR valve is opening but do not know if the flow is adequate.

Any suggestions, I'm getting frustrated!!!!!!

[gator2764]

I am not sure of what the readings should be. One thing you can do is take the egr valve off and see if the car runs the same. If it runs ok with it off the ports are clogged up. It should run like hell if they are clear. do not spray carb cleaner into the diaphram, just in the steel lines and the two intake ports. I had to run a screwdriver in mine just to pick out the carbon.

[jeffromax]

I applied an external vacuum source to the EGR valve and the the car began to run badly and even cut off at one point.
I did notice that the VSV is open whether the engine is cold or hot, would that cause this sort of problem?