After going in circles trying to find this random, phantom misfire with no codes and clean plugs...I finally made the connection!


When I'm running on fumes, the car runs GREAT. I've got issues filling up which were covered in a TSB, so I believe the issue is the Canister Close Valve (CCV) is stuck. It may need charcoal canisters as well, but when I go to fill up, it burps up the filler neck and trips the auto-off on the pump.


My "a-ha" moment? Drove the car to the gas station, running great. Put about 3 gallons into it, pulled out, and it immediately started hiccupping and losing power. BINGO! It's got to be raw fuel or very excessive vapors going from the EVAP system into the motor causing it to randomly run rich. It explains the plugs coming up good...it explains why it hasn't set any misfire codes...it explains why the fuel trims are normal across the board except for a few random spikes that were all in the negative..

So happy that I've got somewhere to start now! I'm gonna check the vent lines, etc and most likely just order the CCV and both Charcoal Canisters to be safe, assuming I can find them.

God do I hope I'm right!

 

Well, so far so good... It's still not running 100%, but it's not falling on its face either. I suspect that I have more than one issue here.

I left the Charcoal Canister Vent solenoid plug connected, but disconnected the solenoid itself from the canister assuming that it's stuck closed. This will let it vent to atmosphere.

When I looked on the driver's side where the vent line goes down, it merges with the EVAP hard-line that runs to the motor just *before* the canister, then plugs into the canister. Because it hits the hard line BEFORE the canister, it's easy to imagine that during fill-up, as it burps up the filler neck, liquid fuel is crossing over into the hardline.

I ran out of time this evening to trace them around the engine bay so I disconnected the small vacuum line in the rear of the Purge Solenoid and plugged/capped it on both ends, but I think I isolated the wrong line since it threw a Check Engine light immediately and at idle. The hardline seems to run into the EVAP Purge Solenoid, next to a second line of equal diameter, which must be the engine-side of the system.

Perhaps the small rubber line in the back of the Purge Solenoid is a vacuum signal to it but not the vapor line itself..... Back to AllData and the Electronic Parts Catalogue!

 

My ride is on a similar ordeal. I'm in for whatever you find out! It's so annoying haha.

 

The CCV (Canister Close Valve) was definitely stuck, so removing it from the canister solved my fuel filling issue. Because I left it plugged in, I've got no Check Engine light so far.

It's a lot better than it was, but I believe I've got a weak ignition coil also due to the loss of power and light engine vibration on acceleration. They're all identical OEM parts, none of them have any damage whatsoever that would indicate arcing or some other fault...none of the plugs stand out from the rest either...

Due to the cost of the coils, my plan is to purchase 1 coil and install it on Cylinder 1 then drive it for a day. If there is no change, I'll swap it to Cylinder 2 and reinstall the OEM coil on Cylinder 1.

So on and so forth until I've either got the coil isolated, or there is no change, in which case I'll shift my focus.