Ok, so I have Toyota Camry 2000 V6 3L that recently shows a Check Engine Code that when hooked up to a scanner tells me that it is "EGR Flow Insufficient". The car idles rough and it hesitates when going to accelerate. I replaced the EGR valve in the car but the problem still exists. When I disconnect the vacuum line connected to the EGR the car now idles smoothly but the Engine light is still on. The whole vacuum system comes from the intake and goes to some sort of purple diaphragm that then connects to a solenoid with two wires and three vacuum lines,one which connects to the purple diaphragm, one which connects to the black type cylinder and then to the EGR Valve and the other line goes to the air box. I would assume that there is something obviously wrong with one of these three components and I am wondering how I would test this to diagnose which one needs to be replaced.

 

The system is operated by vacuum. The solenoid via computer control turns the vacuum to the system on/off.

One line from the solenoid runs to a diaphragm type can then to intake manifold. The can may be some kind of accumulator to dampen out solenoid on/off pulses at the EGR diaphragm.

One lines runs to the EGR valve inside being a diaphragm operated by vacuum. The diaphragm moves the EGR valve.

The EGR valve controls gas flow from the exhaust to the intake systems.

The valve has an electronic position sensor connected to the computer to determine how open/closed.

There is a temp sensor on the exhaust exit port connected to the computer.

The exhaust gas connections/pipes are metal.

The code is set if the gas temp as measured by the temp sensor does not exceed 95F above ambient air temp after the engine has warmed up and the car operated at 50 mph for 3-5 minutes. It takes 2 test failures to set the code.

The code is not going to reset unless manually done so or the test is repeated (under conditions above) and the system passes.

The EGR system should be off (no gas being routed to engine) when the engine is idling, not warmed up, deceleration, light engine load and RPM over 4K.

If the engine idles poorly and you remove the correct line to the solenoid (no vacuum being available to operate the system) and the engine now operates OK there may be an air leak in the system (too much air into the engine). Or gas is being routed into the engine, the system should be off at idle (no gas).

 

So from what I understand from what you're saying here: Removing the connection from the purple diaphragm to the EGR valve removes the vacuum created by the diaphragm?

So how would an air leak in the system providing too much air into the engine be the problem, when disconnecting the the line with the black cylinder would create an even bigger air leak, therefore putting even more air into the engine, when actually, disconnecting the line with the cylinder makes the engine runs fine?

It seems like you're getting somewhere with it and then just contradicting yourself.

 

With this code, the engine typically idles normally as the EGR system is off. But the engine idles poorly and something else may be going on.

The EGR system should be off if the vacuum line that powers it is disconnected. But the engine runs better with the line off (assuming it is the correct line).

One reason for poor idle can be an air leak, such as a somehow air was being routed via the now disconnected hose back into the engine behind the throttle plate.

Or the EGR valve is not closing fully when the system should be off. Removing the hose causes the EGR to turn off, the valve may now be fully closed.

You might remove the vacuum hose from the EGR valve (and plug it) then determine what happens to the idle. If the idle is still poor (the same) the problem would appear to be with the components before the EGR valve.

 

Ok, here is what I just tried:

I started the car with the vacuum hose disconnected from the EGR Valve and it started fine and idled like normal.

As soon as I plugged the vacuum hose back into the EGR Valve, it instantly started to idle poorly.

I then disconnected the vacuum hose again and as usual it began to idle normally again.

After doing this I plugged the vacuum hose with a screwdriver and let it sit for 20 second, and nothing happened. The car still idled fine.

I put my finger to the end of the vacuum hose while it was disconnected and while the car was idling fine and the hose was giving vacuum. Is it supposed to be doing this?

 

Determine if the hose removed from the EGR valve is pulling vacuum at idle. There should NOT be vacuum at this hose when the engine is at idle as the computer is supposed turn the VSV valve off (the solenoid with the 2 wires and 3 hoses).

The solenoid valve could be stuck open or the computer is still powering the valve (12V) to keep the valve open (not common). A volt meter will determine if the solenoid has 12V at engine idle.

The valve can be tested.

When the DC power is disconnect the intake port of the valve connected to the vacuum line you have been disconnecting should not pass air to the line connected to the EGR valve.

When powered, the 2 lines should be connected.

 

So I checked the power to VSV valve on idle and it was running at 4V, not enough to power it.

So clearly it wasn't a power issue.

I then plugged in the vacuum hose to the EGR and as usual is started to idle poorly.

I then gave the VSV a smack to try and loosen it from what you assumed as it being stuck. And sure enough, I guess is loosened and the car began to idle perfectly fine!

I ordered a new VSV from our dealer and it should be in tomorrow and hopefully the car will be running fine!

I want to thank you so much for being extremely helpful with the issue will keep you posted on if the new VSV valve solves the problem.

Thanks again!

-Tyler D

 

Great!