03ztrackfun

Hello, 03' Z 6speed. 130K miles. I'm the new owner as of about 3 months ago. Couple weeks ago car developed an issue; during high load at approx. 3500-4000 rpms would act as if there is a bad miss, or fuel delivery problem. Under light load will get up a little higher in rev range before the symptom is present about 4500-5000 rpm. Also the intake noise is more pronounced (louder). During Idle and low Rpm the engine is smooth and normal. Also when in neutral engine will fully rev out to redline without any symptoms noticed.
This went on for a few drive cycles without tripping a Check engine light.
Finally got a CEL, I did the little self diagnosis and got the p0455 code. I removed the EVAP Canister cleaned it off, inspected for damage, for strong fuel smell, and water... all was fine. checked for 12 volts at the Vent Control Valve plug and that was fine, applied 12 volts to the actual VCV and it failed to close so I replaced it. Tested the new VCV before installing and it closed fine.

Now, unfortunately I'm still having the exact same issue/symptoms as well as the p0455. I've read every related link on this forum and I never read anyone mention the symptoms my car is displaying. Before going to the dealership thought I'd see if I could get a little help here. Seems the EVAP Purge Valve is a common failure part, before I spend more money I'd like to try to confirm it to be the cause. Plus I want to learn more about my Z.

Thanks,
Rich

03ztrackfun

Quick update. Earlier today I removed my Evap purge control valve to check couple simple functions I'm able to test. Verified 12 volts at electrical connector, blew into ports and verified the EPCV is closed with no voltage applied. Blew compressed air into both vacuum hoses, one vented into the air intake tube, the other vents into the fuel tank; I could hear the excessive air being vented out the fuel cap relief.

Took the car out for a drive all highway. CEL still on after about20mile trip along with the problem I described in the first post. During the return 20 mile trip home the CEL went off... although the running problem still is present, perhaps I have/had more than one issue. I'll check new CEL codes when the CEL light is tripped again.
Any thoughts ??

03ztrackfun

Update. The p0455 code was successfully resolved as mentioned above. The drivability issue turned out to be a failed passenger side catalyst converter element. I was able to remove the catalyst element and now my Z runs perfectly normal once again.