Stumped by Fueling Issues (P2293)

[Mirandaro]

Hi all,
apologies in advance for the long post, but been chasing this one for awhile and at my wit's end...bit of background:
Car: 2006 A4 quattro, base, 6 speed manual, 133K
History: recently had the cam follower fail (which only had about 25K on it), which totally trashed the intake cam and hpfp. The piston on the hpfp had ground down past the retainer so the follower was gone for awhile. Anyways, replaced pretty much every single component (short of injectors) in the fueling system: new intake cam, timing chain, chain tensioner, phaser, prv, hpfp, cam follower, rail pressure sensor, pressure sensor on hpfp, cam position sensor, fuel filter. I even changed plugs and coils for good measure. Car runs beautifully, however, would go into limp mode whenever I got onto the gas and then started throwing a bunch of codes, most notably p2293 - 002 - Inadequate performance, p310B - 004 - Fuel Pressure Outside Specification, and p000a - 008 - slow response - intermittent.
As the hpfp was brand new, w/ new follower, I decided to see how the lpfp was performing...mind you, I had replaced it a couple years ago to get rid of a p00089 code a few years prior (probably only 35k on the lpfp). Hooked up to VCDS, measuring block 106, showed at idle (car warmed up), lpfp duty cycle was at 83.1%. Figured, I found the problem, so bought a brand new VDO/Continental lpfp, installed it in the car, and remeasured...still operating at 75+% duty cycle at idle (at operating temp), however, the P310B code was now gone (along w/ the P000A code). The only code now remaining is the p2293 for the N276/hpfp. I tested the N276 using VCDS and I can hear it cycling when I run the test on it. However, still have the code and the car is still in limp mode. Also, looking at actual vs. specified fuel pressures (measuring block 230), it's showing a 20+ bar differential between actual and specified just at idle.
Questions:
- Before I replaced the lpfp, difference between actual and specified fuel pressure was only 1 bar or so, until I got on the throttle, then the delta would jump to 20+ bar and the car would go into limp mode. With the new lpfp in, my idle at operating temp is still around 75% duty cycle, and the difference between actual and specified fuel pressure is now 20+ bar at idle (warm). P310b code is no longer showing in VCDS with the new pump in, but at 75% duty cycle, seems I got a bad lpfp? I expected duty cycle to drop to 40-50% w/ the new lpfp. It went to 50% immediately after I started the car w/ the new pump in it, but them climbed to the 75% mark once it warmed up and stayed there.
- For the remaining p2293 code, before I go an buy another hpfp (again, the one in there is brand new), any other thoughts on what could causing this code that I haven't already replaced? I just can't believe I got both a bad lpfp and hpfp at the same time, but these codes are not going away and car is constantly in limp mode.
Happy to post logs if that'll help, but I figured I just try to explain what I'm seeing here. Thanks in advance all--

[Older_not_Wiser]

There is a VIN split on the rail pressure sensor. Are you sure you are using the correct one?

The P000a code is a N205 or cam timing code, and I would not expect if the cam were mis-timed that it would cause the fuel pressure issues/codes. Maybe there is more than one thing going on here. Have you re-verified the cam is tied correctly?

If not that, then would look at possible restriction, LPFP, LPFP Controller.

[Mirandaro]

Yup, verified correct rail sensor, and even swapped back in the original sensor...still throwing the code and in limp mode. The P000a code is now gone, which disappeared (oddly), after replacement of the lpfp...not sure how it's tied to the lpfp, but figured there's a mix of things happening and some combo of issues caused that code to show up. The only code currently showing is p2293, suggesting hpfp, but that's new (as is the follower), so not sure what else to check. I'm thinking I got a bum hpfp, but I'd hate to buy another one if there's a possibility it's something else. Thing that's driving me nuts, is that prior to replacing the lpfp, the delta between my specified and actual rail pressures was less than a couple bar at idle...it would jump to 20+ bar differential when getting on the throttle, which was putting the car into limp mode. After replacing the lpfp, the fuel pressure differential between specified and actual is now 20 bar at idle (car at operating temp), and duty cycle is still beyond 70% (at idle). I'm thinking I'll dig it back out of the fuel tank and recheck all the connections...maybe I pinched the in tank fuel line that connects to the lpfp somehow? Otherwise, maybe I got a bad lpfp? Seems weird that the lpfp is still working as hard as it is at idle, and now my rail pressure is way low...I figure it's either a bad unit or pinched something when replacing it. All that said, I'm still getting the p2293, which has dogged me for months now...despite a new hpfp, intake, cam, etc.

[Jayz691]

Could be bad lpfp controller. Have you logged your fuel pressures(230,231) during actual driving? Like do a pull, untill it cuts, then see whats going on. Is the hpfp a genuine or hitachi? Not an "offbrand" from eBay or somethin?
Side note, really hate fuel issues on these, lol.

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[RickV]

Is this possible?
https://www.myfastgti.com/threads/po...-faults.43651/

[Jayz691]

Is this possible?
https://www.myfastgti.com/threads/po...-faults.43651/

Yes, i had this happen. Check your low side pressure. Mine was split, and a flap of it would block the hpfp inlet. Would start and idle. Once I got on it, it would die, and not start for a few hours. After the pressure would drop some, it would start. But could have different symptoms, depending.
When it happened, it left me stranded. Only time in 5 years, and a $5 fix, lol.

Happening more and more cuz of people removing the hose, to check CF. Ya can check your follower without removing this hose, for future reference.1003190238.jpg

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[RickV]

I just noticed this on mine too when I was moving my hpfp over to my replacement engine. I actually google searched the number on the hose to get a replacement and came across that link. That little piece of oem hose is like $30! I think I'll check my local automotive stores and see if I can buy a small piece of similar hose there.

[Jayz691]

I just noticed this on mine too when I was moving my hpfp over to my replacement engine. I actually google searched the number on the hose to get a replacement and came across that link. That little piece of oem hose is like $30! I think I'll check my local automotive stores and see if I can buy a small piece of similar hose there.

Yeah, must have went up. Was like $7 when I replaced mine. But its like 5/16" or 3/8" fuel hose..
Here, $17 now, cuz only pre-made is genuine. Ya wanna see something really crazy, look up the little piece of 1" hose that goes from VC to rear breather pipe. Its like $50!!

https://www.fcpeuro.com/products/aud...RoCHR0QAvD_BwE

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[RickV]

That's a decent price but then you add shipping and tax and you're back to $30. Lol
I actually bought 5/16" today. 3/8" was too big and wouldn't grab the barbed fittings. 5/16" fits on the barb nicely but it is a tad smaller. Not by much though, we're talking thousandths. I'm sure it'll be fine, it's a short piece of hose anyway. At $2.50 a foot I couldn't say no. Lol

[Jayz691]

That's a decent price but then you add shipping and tax and you're back to $30. Lol
I actually bought 5/16" today. 3/8" was too big and wouldn't grab the barbed fittings. 5/16" fits on the barb nicely but it is a tad smaller. Not by much though, we're talking thousandths. I'm sure it'll be fine, it's a short piece of hose anyway. At $2.50 a foot I couldn't say no. Lol

Yeah, long as it don't kink with the bend, it'll be fine.

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[Mirandaro]

Thanks for the input, guys. I ended up biting the bullet and getting another new HPFP (OEM Hitachi) after seeing a couple folks post (here and on the Ross-Tech forum) to only use original HPFPs...the first one I bought was off-brand. I also pulled the LPFP back out and reinstalled, ensuring nothing pinched and when putting it back together, it felt more seated going back in, so I think I may have not fully seated the unit the first time. Combined w/ the new Hitachi HPFP, I'm now looking at LPFP duty cycle around 50% at warm idle, and differential between specified and actual rail pressure is around 1 bar at all rev ranges. Still have a cam position error, but got rid of the p2293 (and associated limp mode) which has dogged me for weeks! Appreciate all the thoughts on here--

[Jayz691]

Seen a few people have fuel regulation codes with brand new, cheap hpfp's. And also seen some be good. Best to stick with Hitachi or genuine(if ya wanna spend double).

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