P0401 mystery

[Art Lessing]

1996 B2300....P0401.... I cleaned with wire brushes and drills everything, including intake ports etc..., replaced vac hoses, swapped DPFE for new, swapped Solenoid for new, tested egr and it kills the engine quickly with vacuum applied. CLeaned throttle body, made sure all vacuum hoses are airtight. Still no love. Truck runs fine, albiet a bit cool....170-80 degrees ECT....126degrees IAT.......

stumped....Did I miss something? I don't have much hair left ....

 

[franklin2]

Is your exhaust system completely stock?

 

[Art Lessing]

It is totally stock....I found that the one of the hoses to the canister was leaky so I replaced it.and cleared the code...no code yet however the thing now hesitates a bit in the first few degrees of the gas pedal travel .....

 

[Mechrick]

Pop the top off the Egr Vacuum Regulator and plug off the vent tube with a thumb with the engine idling. With the vent tube plugged, full vacuum will be applied to the EGR valve, therefore it should open. This is a good way to check the vacuum path from the engine all the way to the valve.

To test the electrical side, put a vac gauge on the EGR vac line and do a running code test with your code puller. The vac gauge should show vacuum briefly when the PCM requests it during the running test.