Boxter with various codes/rough idle/misfire

[ziggyrama]

On 4/14/2023 at 4:09 PM, ziggyrama said:

After some testing, there doesn’t appear to be any continuity between pin 1 on the valve and pin 7 at the DME. Actually there is a very low resistance of about 70 ohms between pin 1 and ground. 

I've traced the wire through a loom that travels down the left side of the car and up behind the dashboard; there is continuity from PIN 7 to that spot under the dash, but doesn't seem to be from there to the valve. Without any way to really trace it behind the dash, I don't know where the short or cut may be. Any thoughts? Are there any plugs between there and the valve that you are aware of? Thank you

[JFP in PA]

12 minutes ago, ziggyrama said:

I've traced the wire through a loom that travels down the left side of the car and up behind the dashboard; there is continuity from PIN 7 to that spot under the dash, but doesn't seem to be from there to the valve. Without any way to really trace it behind the dash, I don't know where the short or cut may be. Any thoughts? Are there any plugs between there and the valve that you are aware of? Thank you

You need to get a wiring diagram for the car to find that out.

[ziggyrama]

After some more troubleshooting, I decided to bypass the factory wire harness and do some more testing. The valve now has a low voltage (around 7v) and it very similar to what the author is describing in this old post. The car no longer has the original P0447 but is still misfiring with a P0306/P1318 error. In the post, the author had replaced the fuel line vent valve which was also showing a low voltage. Is there any way to test this valve without removing it or do you have any other suggestions for what may be the issue now? Thank you

 

[JFP in PA]

In order to do any tests on this valve, you need to get access to it, so by that point you might as well pull it for bench testing. but that valve malfunctioning should not cause a single cylinder misfire on cylinder #6.  Are you completely sure you don't have a coil/plug/injector issue on that hole?

[ziggyrama]

20 minutes ago, JFP in PA said:

In order to do any tests on this valve, you need to get access to it, so by that point you might as well pull it for bench testing. but that valve malfunctioning should not cause a single cylinder misfire on cylinder #6.  Are you completely sure you don't have a coil/plug/injector issue on that hole?

actually, I am not sure; the car drove perfectly fine one minute, and then literally threw all these codes at once on the next drive. Would it be more beneficial at this point to check the coils/plugs/injectors rather than chasing the EVAP issue? My only insight is that the car idles rough due to the misfire and has a very strong gas smell.

[JFP in PA]

Both problems point to a dead or partially dead hole, question is why?  Pull the plug and look at it, if it is black and sooty, it isn't firing consistently.  Question then is why, the EVAP system is incapable of killing a single cylinder, so it is something closer to that cylinder (coil pack, plug, injector, harness and connections, etc.).

[ziggyrama]

On 4/18/2023 at 9:48 AM, JFP in PA said:

Both problems point to a dead or partially dead hole, question is why?  Pull the plug and look at it, if it is black and sooty, it isn't firing consistently.  Question then is why, the EVAP system is incapable of killing a single cylinder, so it is something closer to that cylinder (coil pack, plug, injector, harness and connections, etc.).

I pulled the coil pack for cylinder 6 and 5; both test the same and the spark plugs look good. There doesn't appear to be any physical issues with the harness or connections that I can see. I've read on some other forums about issues regarding the ECU and wondering if there is any other tests I can preform? With the other weird electrical issues that occurred at the same time, is this a real possibility? Thanks