[Shotimes] Codes for 95ATX

[Kevin & Cheryl Airth]

Kirk:
 Your EGR passages in the intake manifold are probably plugged with carbon.
The EGR valve was not bad. There are two pipe plugs that can be removed to
get at the carbon. On is on the backside of the manifold facing the firewall
on the drivers side. Remove it with a Allen wrench. It will be very tight.
Steel plug in Aluminum. The other Allen plug is not easily reachable with
the intake manifold on the engine. Next take the rubber hose off the
throttle body and block the butterfly open. I went ahead and removed the TB
because it gives much better access. Behind the TB you will see two 1/4"
diameter holes or nostrils on the bottom of the intake floor. It is just
before the manifold splits into two separate chambers. These nostrils build
up plugs of carbon. Now the nostrils connect in a straight line to the Allen
plug you just removed. Use carburetor cleaner, stiff piece of
wire,compressed air what ever you have to make sure that passage is open. I
stuff a rag in each leg of the intake manifold past where the nostrils are,
prior to cleaning, to prevent the crud getting in the engine. Then I use a
shop vac. to vacuum up all the junk that comes out of the passages.
Reinstall Allen plug. Remove the EGR valve and make sure you are connected
to the nostrils in the intake. I usually spray carburetor cleaner in this
port with the engine running. But first clean it manually to make sure you
do have a open passage. I tried multiple times just using the cleaner first
and it will NOT fix a blocked passage.

Next check the DPFE (Differential Pressure Feedback EGR) to see if the
rubber hoses are cracked or broken or plugged with carbon. The DPFE is the
metal rectangular box attached to the back of the manifold, very close to
the Allen plug you removed. It should have two rubber hoses attached to the
bottom side with spring clamps. This is not as common as the manifold
passages but check it anyway. This should fix the 332 code.

172 is just the rear O2 sensor running lean. I found that any small misfires
from oil/water in the plug wells will throw a O2 sensor code. So have you
checked the plug wells? How old are the plugs and wires? I would suspect oil
in the back plug wells because it's much harder to change things in the
back. I have found it quite common for repair shops to change only the front
easy to get at plugs and ignore the back three, but charge for a "complete"
tune-up.

 Finally disconnect the battery for about 10 minutes, reconnect and then
drive around to make sure the car will throw the same codes. If you did not
clear the PCM memory when you replaced the parts it might be a old code. The
system will clear the codes but it takes a large number of on-off cycles.

Does the car act any different when the check engine light comes on?
Do you have the proper Helm repair manual?
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> The CE light keeps going on intermittently.
> The codes read 172 and 332.
> I have replaced both O2 sensors and the EGR valve.
> Both of these codes keep showing up.
> The car is a 95 ATX with 146,000.
> Any suggestions are appreciated.
> TIA,
> Kirk