I just got done with a cat removal and have a small exhaust leak at the exhaust gasket after 02 sensors. There is a really strong smell of fuel inside the car but not really outside. The shop had the back seats out. I’m going to check all fuel fittings. Where all should I check? And i wouldn’t think the smell would be this strong so I’m almost certain it’s not just from the cat delete.
I would open the doors to eliminate any fuel smell so you can get a good base.
If you’ve opened the doors and windows and still smell fuel. I would check under the back seats as that’s where the sending unit and pump is. In my S8 my pump is in the trunk but I believe if I remember correctly the S6 has that under the back seat.
If you have to lift off the back seats once you have them removed that would be a good time to key the car on. That would prime the pump and if there was a leak that might be enough to show some signs.
The larger chance of fuel would probably be coming from the engine bay. It’s not uncommon to get a small fuel weep from the hi pressure fitting side of the fuel lines just after the pumps.
If you don’t see or smell fuel there under those conditions. It is possible, I suppose, depending on how big of an exhaust leak you have that you’re smelling fuel from the OEM cat cleaning function where the car runs very fat for small bursts of time to clean the cat.
But I would start with those two spots. Especially once the car is running bring under the hood if there was fuel present when the car is running should be obvious
I think the problem was they had a fuel leak and it was all over still. Quick degreaser and spray down of the engine bay and its gone for now. Will still keep an eye out.
Smell came back roughly 30 minutes after driving around.
I assume they pulled the engine for the cat work?
If so, you want to concentrate your search on the lines they disconnected when they pulled the engine.
Ed
Thats what I’m focusing on. Have tried tightening all lines and got nowhere. Also not seeing any fuel. Just smelling it.
The one large line down low behind the engine hoist on the passenger side is the one I would be looking at.
When you have smelled the fuel, have you gone immediately to the engine bay and tried to isolate it there?
Ed
If you have a vag com open up and pull up your HP fuel values and LP values. You should be able to see the pressure at the rail valve. The check valve will stop the pressure from leaking back into the tank. Check to see if there is pressure falling off and where. That can then lead you to your next point of investigation.
You can prime the fuel system by opening the door and then again by keying the car up but not starting. You can’t indefinitely keep key cycling up the car. I think the time out amount is 5.
If you look at the values that can be a good place to start. Look to see if you see the pressure falling off.
Also remember you can do an output test in vag com as well.The big advantage with an output test is that you don’t have to actually have the car running. You can run the pump and trigger the injectors in the output test. Doing an output test should help you in an environment where you don’t have to actually have the car running but you can drive components in your area of investigation.
If you wish to do more than one output test or system prime cycle past the time out amount. Pull the battery cable zero out the voltage storage in any module by putting the cables together for a few seconds. Then you should be able to do again for a second round. Don’t trigger the injectors too many times as it could lead to a cylinder flooding issue. While it’s unlikely it’s still possible.
Ill check that today and let you know what I find. The smell was fairly strong. Fuel smell doesn’t really bother me much as I have been around small circle track racing for a decent amount of time and don’t have issues but I had the windows down and still was bothered by the smell. I appreciate the help.
I have and I only slightly smell fuel but I can’t source it. I’ve looked at every fuel line I know and don’t see any visual leaks
I haven’t looked, but does this car have a fuel vapor catch can in the loop up front someplace. I’ll look later if I get a chance, but maybe rather than a supply line problem it is a vent line problem?
I could do what the count suggests as well. If it holds pressure then you need to look elsewhere.
Ed
Looking at the fuel rail pressure primed the system a couple times and it got to about 107 psi then slowly started losing a couple psi every 5-10 seconds. Consistently. After that I started it and let it run for a minute. I let it run for a minute or so and turned it back off. Keyed on and checked again and it was up to 1500 psi and climbing up as I watched. Got up to almost 1600
So still haven’t found any kind of leak but I’m starting to think its from the exhaust leak. The exhaust leak is pretty good size. Waiting for some new gaskets where the end of the manifold y is. The gasket got blown out from the shop tightening the bolts bad and pinching the edges and it bent the flange. Hopefully I’m able to geg it straightened out and together good. There’s no fuel anywhere that I can find but misfires at idle and I’m wondering if the cat delete and not being able to get the tune on is why that’s happening. I’m going to change plugs and see if that helps and get the tune on there. The stong gas smell is the same out of the back of the exhaust as well. I also got these 4 codes and wondering if that could be because of not having the tune yet or if i should be looking for a possible vacuum leak. Didn’t get those until about 2 days after getting the car back.
It very well could be an exhaust leak. Fuel leaks that you can smell would generally produce fuel that you can see. While the fuel will evaporate quite quickly it won’t evap quick enough to not be seen.
On the other side you have exhaust leaks. Exhaust leaks would tend to be like your seeing. And thats where the smell comes over time. You will smell the fuel smell more if you don’t have cats as the car runs rich when the motor is hot to try and cool it down.
This is why the JHM intake spacers help in part by reducing the intake air temps. You can see cooler EGT values.
With all of these code. I would 100% look into getting that fixed before moving on. Those codes are not good.