Old Guy (or any other expert forum member) I have a real pickle of a situation, and I'm at a loss for what to check for.
My Car
I have an 05 B6 A4 Ultrasport 1.8t MT Quatro. It has a full APR K04 turbo upgrade kit, Miltek full exhaust, ECS Tuning test pipe, Racetec FMIC, Forge TIP, TT Injectors, 034 Motorsports updated breather hose/check valve kit, Cabonio Intake, and full APR ECU tuning for those mods.
The Issue
I have been having fueling issues where I will get a misfire, flashing CEL, and stuttering but ONLY when I've gone about 200 miles into a full tank of gas. Before this happens I hear a whining in the fuel pump for about 20 or so miles before the stuttering and flashing CEL misfires begin. If I continue to drive it's as if my car runs out of gas.
What I've Tried
So my first thought was a fuel filter, so I replaced the fuel filter with a new one. The problem persisted and the stuttering and misfired (flashing CEL) continued and at this point I hadn't had any CEL codes show up. So I decided to try the 034 Motorsports Bosch 040 high flow fuel pump. I had replaced both sending units the month before so I had a shop check to see if the were causing an issue with the pump. They opened up the sending units in the gas tank in both drivers and passenger side and found nothing. So upon pulling out the old fuel pump and pump basket I found a TON of orange rubber fuel tank gasket pieces in the fuel tank! the entire inner ring of gasket material had disintegrated into pieces from little specs to 3" in length! It took me 6 hours with my arm in the gas tank, a 3" strainer, a small sparkproof flashlight, and a extendable dentist mirror to fish out the pieces. I am pretty sure (??) that I got the pieces out. Is it safe to assume that the pieces were blocking the surge tank orifice and the fuel pump was straining to get gas to the injectors causing a lean mixture and the misfiring (flashing CEL)? Well that's what I was hoping.
So I installed the 040 fuel pump.
I installed the 040 fuel pump with the aluminum ring and utilized the stock basket. I had a 5 gal fuel container with 91oct (I'm in Utah it's the best we got) and filled up the tank, then drove and did a full fill up. So far so good, or so I thought. Just yesterday I reached the 200 mile mark and again I am hearing a cycling humming noise from the fuel pump and I'm thinking to myself "maybe this is just how it sounds, it IS a new pump and maybe it's just louder because it's a higher flowing pump but, inevitably, 20 or so miles later I get the misfire (flashing CEL) and the stuttering upon high acceleration (which is when it first starts up, during a moment of high acceleration and then has issues and almost dies shortly after that). I was a block form my house so I pulled in and I've left it in my garage since (overnight) as it is.
Notes
-I did get a cel code just before I put the 034 Motorsports 040 pump in. I got a P0011, cam position timing. I had replaced the Valve cover gasket a month earlier and the visual timing chain looked fine so I attributed this to the lean fueling issue and I gassed up and the CEL disappeared without a CEL code clear. I also must note that I get NO shuddering, NO flashing CEL, NO loud fuel pump when there is a full tank of gas, only at about 200 miles.
-AFTER I installed the fuel pump the cabin really smelled of gas, the source was right around the fuel pump door. I imagine I spilled gas all over the place fishing stuff out. It has slowly gotten less and less smelly but, I did get another CEL. This time it was P0456 EVAP small leak. I ordered a new N80 purge valve and the check valve that is adjacent to it (which just came today) but the CEL disappeared a day later, as some of the gas smell evaporated out of the car. So I'm not sure if it was just overwhelmed by fumes and that triggered the CEL or what. I will still install the N80 and check valve tomorrow.
-I have another fuel filter with 034 Motorsports upgraded braided AN fitting fuel lines to the fuel rail.
What do I do??
-I'll install the new fuel filter, fuel lines, n80valve and check valves tomorrow.
-I'll open up the gas tank again and see if there is more debris that I missed clogging up the intake to the surge tank and remove what I find if anything.
-Some on the forum have suggested the misfire (flashing CEL) is from the coil packs and/or spark plugs. I have only owned the car for 4 months or so and I haven't changed the CP or SP but I feel if it were either of those it would stutter and have issues all the time not just AFTER 200 miles have passed on every full tank of fuel (never fail).
-I know there are two tanks or at least two chambers. Is there a pressurized hose connecting the two, could the issue be actual fuel levels? Like maybe the other tank isn't getting fuel over to the fuel pump side? I just don't think so because the level it starts acting up it has fuel, just below the top of the fuel pump housing/surge tank top.
-What thoughts do you have, what am I missing, what would you suggest I check? I'M GOING BONKERS!
Thank you for any help!!!
AF
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Originally Posted by DownhillA4
Stage Stock.0 1.8t TIP to Stage 3+ 450hp 2.7t/01E Swap in progress
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