EGR Valve

[antonbrn]

Can anyone tell me where the EGR Valve is located on a 2001 Chevy Venture? Pics of its location would be nice, if possible

Thanks

[Tech II]

I think the bracket of the tranny dipstick tube(near top of it), is attached to it....

[antonbrn]

Originally Posted by Tech II

I think the bracket of the tranny dipstick tube(near top of it), is attached to it....

Thanks, I see it now. I've been getting problem code p0401. After I get back from vacation, I hope to take out and clean the EGR valve. I've also read it is a good idea to clean the ports. Do you, or anyone else, know where the ports are located and how to get to them?
Any help would be much appreciated.

Thanks

[Tech II]

There is only one way to check an EGR.....that is with a scan tool that is capable of commanding the EGR open, in increments....

You need to look at several things as far as the test goes.....

One is pintle position....when the EGR is commanded off, pintle position should be 0 %......if it reads anything else, EGR needs replacement (rare that something is stuck under the pintle).....

Next as you open the the EGR progressively wider, the engine should start to stumble and get worse the more you open it.....

Third, as you open the EGR, should see a drop in MAP pressure and also O2 data.....

there is a flex tube that runs from the rear exhaust manifold to the EGR....have never seen this plugged......have seen bad EGR's.....if the EGR is opening and opens the amount it is commanded, and there is little change in the running of the vehicle, then you could have a problem in the upper plenum......this is the passageway from the EGR through the intake....it is a small opening, and if crudded up, could fail the flow test....

Here's how the flow test works.....with car at normal operating temp, when you get the car up to speed, and then take your foot off the gas pedal and start to decelerate, the PCM or computer does an EGR test.... it slightly opens the EGR, and looks for a corresponding increase in Map voltage.......if it doesn't see this increase, that means flow is insufficient or restricted.....

[autojoe]

you could manually operate the egr valve without a scan tool and see if rpm change.if you remove egr valve and with a screwdriver push down on the pintle and see if it releases smoothly without sticking....i have seen these stick.

[Tech II]

How do you manually operate an electronic EGR?

[autojoe]

you test circuit for solenoid and find out if it is power or ground side switched.once you know this you can provide a power or a ground to solenoid using a jumper wire but if you do this wrong you can fry the driver inside the pcm.the other way on this egr is pins a&e the 2 outside pins are for the solenoid the other 3 pins are for the pontentiometer for valve position to pcm.power/ground/signal....3 wire pontentometer.you disconnect the egr connector and supply battery voltage with a fused jumper to terminal(e)of the egr valve and then take a jumper and hook to pin(a)of the egr valve.you hook a vacuum gauge to large manifold vacuum like pcv and have someone start vehicle and with steady rpm around 2000 steady note your manifold vacuum.....now ground the jumper connected to terminal (a)of the egr valve and note manifold vacuum drop on guage.there should be 5-10 inches of vacuum drop.the computer will try to compensate when the engine pukes from egr flow.if you have under 5 inches manifold vacuum drop at 2000 rpm then there is not enough egr flow.....either clogged egr passages or if no drop then possible bad egr valve.you can use this test on all makes to see if adequate egr flow.....sometimes there is flow but not enough to keep the light off.the pcm will not let you do bi-directional controls above idle at 2000 rpm.you could also do this power and ground at idle and see if vehicle stalls or gets very rough without vacuum guage and at 2000 rpm but thsi way you can tell peak drop and see the amount of egr flow.I hope this makes sense.I do alot of solenoid activation with a jumper wire but have to test circuits before providing power or ground depending the type of driver inside the pcm and if you do it wrong you will fry the driver if it happens to be on and some of these pcms are very expensive.I hope this makes sense.

[Tech II]

Guess I was confused by the term "manually".....

The Three EGR's GM used were the vac type, the 3 solenoid type, and then the linear type....

The vacuum type, you could manually check just by reaching under the top and moving the diaphram to open the EGR and see if the car stumbled, or by applying vac to the port.....

The second had three solenoids with different sized orifice ports, which you could electrically activate each circuit to check out.....

The last though, is linear.....that solenoid is "pulse-width" modulated, to vary the opening, along with a pintle position sensor.....only a scan tool can read what the PCM is seeing as the actual position of the pintle vs. what the commanded position is.....The test you are doing is full open, or 100 %.....and as you say, with the EGR wide open, this will cause the engine to stumble and vac pressure to drop......

That only tells you if you have MAJOR blockage or if the EGR is not working at all.....when the PCM runs this test, it does this at a very low percentage, and looks for a corresponding drop in Map pressure.......the flashing in the EGR passageway of the upper plenum could crud up just a enough, so when the test is done, it's enough of a restriction to block low pressure from the exhaust, but not enough to block high pressure from the exhaust(when pintle is commanded wide open)....that's why I say the only way to truly test a linear EGR is with a bidirectional scan tool.....