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2007 Audi A4: P2177 and P0455 codes

I have been having issues with my car. The codes in the title are the ones i have right now but have also had Cylinder 1 misfire and random misfire, aswell as low fuel rail pressure a couple times. I had a stage 2 Eurodyne tune on when the misfires and low fuel rail was present, I downgrades to stage 1 to see if it fixed problems… it didnt, so now I’m on stock tune. Since i’ve been on stock tune I havent had the misfires or low fuel rail. But the 2 codes stated are still existing and my car basically runs like a gas guzzling potato. I just ordered a duralast canister purge valve to see if it might fix the P0455 trying to cheaper options first, But I would really like some better insight on what other solutions there is for my issues.
My mods are:
AFE Pro 5 R Stage 2 Air Intake System
Torxe Cat Back exhaust
Ebay cat delete pipe
GFB DV+

Do you mean the mileage is awful??

Just reading your mods and the steps down from stage 2 to 1 to stock to settle out the low fuel rail pressure issue leads me to think you have a fuel supply issue. Clogged filter, or failing primary fuel pump restricting volume.

The mileage issue, if it is using lots of extra fuel, maybe points in another direction. Answer my question and post the codes you’ve been seeing with the tune and/or ones you have now.That would help a lot.

Just a comment or 2 about this;

This is a federal crime in the US that carries a large fine if caught. Also, we all breath the same air, the cat helps you and us do that. Modern cats are not the restrictive things they were in the past. Please put it back on.

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That’s where I would look for the P2177, probably have air leaks, check ALL the joints/connections in it, or you used to much oil on the filter and contaminated the MAF sensor.

For the P0455, one of the biggest reasons is a faulty gas cap.

Yes the milage is not too great. Other codes i had on tune were cylinder misfires and low fuel rail pressure, i dont have the CEL codes on hand though as they are not current.
Although I appreciate your input, and will look into it, i dont think one or even a couple thousand people with highflow cats or deletes will impact our pollution problem.

I have a dry filter so the maf wouldnt be coated from filter oil but it could be dirty in general. I will check the connections though. And as for the gas cap, i was going to get both the purge valve and cap at the same time but the purge valve is more readily available.

If you had low rail pressure, that may very well create your misfire from the lean condition.

The high boost pressure may have done in your rings as well. A compression test may be in order.

Have you done a fuel pressure test? That’s usually a pretty quick procedure, at least for a shop, and probably where I’d start with this problem. If the fuel pressure isn’t what the ecm thinks it is, the engine will never run correctly. If your engine uses the conventional fuel pressure regulator check to see if there’s any fuel in the vacuum hose connected to it. Shouldn’t be. For the p0455, if the gas cap isn’t the problem, could be any number of places where leaks could occur in the evap system. Two common places reported here for that problem are a valve at the top of the fuel tank and the canister/purge valve area.