slacker7

ferent shops, including a Dealer, and nobody has been able to
permanently clear it.

I just bought a CarChip E/X at a local auto parts store. Pretty
cool little device.

Anyway, I currently have two trouble codes...

P0402 - Exhaust Gas Recirculation Flow Excessive Detected
P0304 - Cylinder 4 Misfire


These are actually the two codes that initially set off my Check
Engine light back in October. I had a hell of time getting it to
pass smog, but finally got passed two weeks ago... after blowing
+$1700.

Here's the detail of the parts that have been replaced, in order:

1) EGR Solenoid
2) EGR Valve
3) Throttle Control Valve
4) A couple of cracked vacuum lines
5) O2 Sensor (upper one... not sure if there's a 2nd one)
6) Catalytic Converter (OBD II cat)
7) Spark Plug wires (I just did these today... they were due
anyway.. will changed the spark plugs tonight/tomorrow)

After getting items 1, 2 & 3 (above), the truck was failing smog
with very high NO readings. My mechanic then changed out item 4,
and ran a pre-test smog check. It passed with flying colors.
Unfortunately, that shop couldn't run the real test because they
cannot certify Gross Polluters, which mine was.

The very next morning, I ran the truck over to someone that can
certify Gross Polluters... And it failed for high NO reading,
again. This mechanic asked me to let him diagnose the problem
and he would guarantee that he would find the problem and get it
to pass. He told me that my Catalytic converter was history. So
I let him install a new one. Sure enough, it passed smog...
Finally :-).

3 days later the damned Check Engine light is back, the
idle is very rough, and the truck is really sputtering at speeds
under 20mph. Also, I'm getting horrendous gas mileage.


Anyone have any guesses on what's going on here?

tia