test for failing EGR valve

I have a 95 Neon with 400,000+ km on it and believe that the EGR valve
is failing.
The car at some points, will not stay idling and will stall if no
throtle is aplied. Other times, it'll idle at 1500+ RPM, and if I shift
gears below 2500RPM, when I press the clutch and release the throtle,
it revs up to about 3000RPM before dropping.

Is there a way of testing to verify that this is the valve that is
failing, and not another problem? I would hate to pay the $125CND for
the valve, and find out that is not the issue.
If it is dirty, can it be cleaned?

Mike
mlawrenc(at)gmail.com

 

you may want to check engine codes
the stalling and stuff has nothing to do with the egr as many racers run egr
block off plates on the egr with little to no effect.

remove throttle body and clean intake manifold.
clean bottom of throttle body
check for vacuum leaks
remove and clean the IAC on the throttle body
then check the throttle position sensor
also try resting the computer see if that helps
use propane torch with out a flame around the intake manifold if idle
increases then replace each runners gasket.

 

Thank you for the ideas.
I was going to try the propane torch this weekend. I will check the
other items as well.

Mike
mlawrenc(at)gmail.com

 

Well... Things are getting worse. The engine is not trying to stall as
often, however, now I have the revving issues.
On the way into the office, the car was revving up to 4k RPM while
waiting for the light to change.
I did notice the sound of air being sucked in or something while
sitting in the car. I was unable (and partly unwilling) to get check
under the hood to find out where the noise was coming from (did not
want to allow the revving to continue any further and not be able to
kill the engine from inside the car).
The one common thing I noticed is that when it does act up, it appears
to be before the car reaches running temp. I do not believe that the
actual temp of the engine is the factor, but think that maybe a sensor
or two that comes into play when the car reaches running temp that may
be correcting the problem.

The one item that was mentioned in passing is that it may be something
to do with the throtle positioning sensor. Would this make sense?

Has anyone heard of this and or have any ideas?

Mike
mlawrenc(at)gmail.com

 

A bad EGR valve can't cause stalling? What happens when an EGR valve
sticks open or is commanded open improperly at idle? The engine will
chug or stall from an excess of inert exaust gas which it is not
metering or compensating for. Blocking off an EGR port just bypasses
an EGR system; it is in no way proof that a faulty EGR system cannot
cause stalling.

Good advice -- free or inexpensive things to look at and clean....

Toyota MDT in MO

 

First check the obvious things: throttle, cruise control, or transaxle
control cable(s) binding, a cable came partially off of the throttle
bellcrank and is holding the throttle open, massive vacuum leak like a
melted PCV hose, etc... The air rushing sound would lead me to check
all large vacuum hoses.

I would discount the TPS as a culprit at this time and look for more
likely causes as outlined above.

Toyota MDT in MO

 

What makes this problem interesting is that it appears to only occur
before the car reaches operating temp. I know there are a number of
sensors that do not come into play until the computer indicates that
the car is at running temp.
This would almost lead me to believe that there are one or more sensors
that is either correcting the problem once the car is warm.
I have repetitivly checked the engine error codes, and have not
received anything other then the 'battery has been disconnected within
so many starts'.
I have even gone as far as checking the condition of the spark plugs
(comes from growing up around two-stroke engines) and have not noticed
anything other then the engine is running a little hot (which appears
to be common between this 95 Neon and my 2001 Neon).
I will be spending this long weekend Removing the intake assembly in
CAI, throtle body and clean it out. Is there any where specific I
should check?

Mike
mlawrenc(at)gmail.com

 

you use a vac gauge to test the egr for proper operation
once the pcm see'e 130 degrees the computer goes into closed loop and
takes reading's for all sensors and acts accordingly. removing the intake
would be a waste of time as far as i see from your post