RS5 Swapped Allroad... Need help diagnosing some issues that pop up

A5/S5/RS5
#1

I want to keep this as concise as possible and not flood the page with multiple “problem post”.

Pulled apart a beautiful and perfect RS5 with 65,000 miles on the engine. Swapped the entire front and rear subframe/drivetrain over and the main issue I’m having is an oil pressure sensor kicking off limp mode around 5000rpm.

Car screams not to rev over 4000rpm and sets it in limp mode until I restart the car. I replaced the sensor today and am still getting the P164B00 code which wasn’t there before the chassis swap (and I put 600 miles on the RS5 prior to pulling). Car runs and drives great otherwise, any ideas?

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#2

Which sensor did you replace? The Oil pressure pressure switch or the Oil pressure regulating vavle (swaps from low to high pressure (just above the left rear side of the oil pan). Have you tried logging the Oil pressure with Vagcom? I think running a log through the Rpm’s would be interesting. Clear the codes and run the logs.

#3

I replaced the switch on the back of the oil filter housing. Suppose I could the regulator valve if it comes to that.

I was in Obd11 and can only seem to find a off/on group for the oil pressure (0 or 1)

#4

Will OBD11 log the oil regulator valve for on/off? Is that the group you’re talking about? If you could run a log with the Regulating valve and slowly increase RPM’s and see when the limp mode cuts in then you might have a culprit. Too bad I’m in Hawaii and my shop is in WA as I’ve got a good used Regulating valve you could try. Although I’d prefer to troubleshoot and log the error before throwing anymore parts at it.

#5

I’m honestly wondering if it’s something I potentially disconnected and never plugged back in when I removed some of the harness/engine… Never had time to check today as I was busy getting the 2.0t swapped RS5 running LOL!

Checking it out tomorrow when I get to work

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#6

Un plugged is generally a short fault. And usually will trip an error code right away.

From what I can remember you’ll get 4000 limit with cam components or related timing error faults. Oil obviously can do the same but you’ll usually get an error on the dash as well but that error for the regulator it’s odd it’s not doing that as well?

hahnmgh63 - Called it clear the code see if it comes back right away. That will let you know short or bad - then move from there.

I’d suggest in the future giving the full code data. Gives us more to go on.

#7

Code goes static when restarting the car. As soon as it see’s over the threshold it’ll go active (limp mode) until I either clear the code or restart the car.

However, once the code is cleared it won’t come back until it meets the over 4000rpm threshold.

Can’t remember the measuring blocks to check cam timing, but will give it a shot later this week. Oil pressure switch is the only fault though.

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#9

I’ve finally had a chance to get a oil pressure gauge and connect it into F22 port.

Workshop manual calls for 20psi at idle and 30psi at 2,000rpm

I’m seeing 25psi and 32psi (respectfully) when the oil temp is at 75°c (the manual calls for 80°c).

3,500 rpm netted me 36psi, but seeing as F22 needs to see 55psi @ 4,000rpm… if say something magically became fucky during the engine swap.

OBDeleven shows the oil pressure regulating valve switching open to closed, and I’m not getting any faults for it… ordering one regardless and swapping them. Other than that, I’m f*cked…

EDIT NOW THAT THE “PRESSURE REGULATOR VALVE” IS REMOVED !
Part number off of it is 06E 115 243 G. Everywhere in finding it, it’s showing up as a VVT solenoid

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#10

Original Valve was a “G”, now superseded to a “H”.


It basically is just a VVT on/off plunger valve, probably used as a VVT valve in another application.

P.S. May sound like a silly request, but are you sure there is an Oil Filter installed in the canister? And if there is, make sure the little know on the bottom of the filter is inserted into the passageway in the canister correctly.

#11

Yup! Just installed a new one…
Rotate til the plunger with o ring meets the hole, click in the seat it, then tq the cap

I tested the solenoid and while it was clicking, I wasn’t able to see the plunger orfice open and close… maybe it was clogged, maybe it wasn’t…

Either way I ordered a new one of FCP and will try it out. Cold start oil pressure was only around 45psi which I know it should be closer to 90 so hopefully the valve was stuck. Warm oil pressure was within spec which leads me to thinking the engine is good.

#12

there’s 2 or 4 of the vvt solenoids fyi

#13

Should be 5

#14

Yep, 4 for the Cams and the one for the Oil pressure Hi/Lo circuit.

#15

Alright… I’m at my wits end on this and starting to think I lost oil pressure during the swap…

I’ve replaced the low/high switch as well as the regulating solenoid. The ECU is registering they’re being triggered via OBD11 and live data view.

I’m able to register the high pressure switch by unthreading it from the block, grounding it out and applying 55psi to it through an air compressor and same for the low pressure so I know the switches + wiring is good.

I pulled both filters and caps tonight with the 4.2 on the left and 5.2 on the right. Other than switching those around I’m at an absolute loss

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#16

I know it’s odd but just like hahmgt63 said check the filter caps and filters. I put in a BRAND new off name filter in a customers car (customer provided filter) and I got the oil pressure error. Swapped back (took out of the oill drain pan the old filter put back in and no issues) and good to go.

Forgive me for not remembering on this. but you were able to drive the car pre swap and this wasn’t an issue correct? Could this be a transfer function issue with the wire harness ECU structure? I ran into that swapping motors on an A4 for someone a few years back.

#17

Filter and caps were swapped with known good one off the V10. The car was running perfect prior to the swap with no codes if any sort. I already repinned the F22 switch to the BCM as the pinout was different between the Allroad and RS5.

Proper function has been verified through OBDeleven and creating a short to ground on the switch. The binary function showing the status of oil pressure switches changes from 0 to 1.

#18

A physical oil pressure gauge shows everything within spec so I ground the F22 wire to the chassis and have full 8500rpm back. I’ll have to live without the safety in place if low oil pressure occurs in the future, but for now it’ll do.

Sounds glorious, next stop is wiring in the sport diff and windshield wipers and should be good to go on the swap!

#19

Great update. What is wrong with the sensor that it’s reading wrong. At this point I’d say that’s the best way forward. No sense in having the car down for an issue that’s not an issue

#20

I honestly don’t know what the issue is/was. The car is running superb so I can say with confidence it’s a non-issue.

F378 (reduced oil pressure switch) wire runs directly into the ecu. Not a a chassis/swap issue.

F22 (the high pressure oil switch) was never telling the ecu it was seeing 55psi above 4,000rpm. That wire goes into the BCM but needs to be repinned as the Allroad pinouts for the Red/White Engine harness T17 connectors are different.

I repinned it correctly, but still had the low oil pressure issue. If somebody happens to stumble on this thread years from now, understand that I never found the root cause, only a “bypass”

#21

Been away for the last week, glad to see you figured out the important side, the real pressure was good all along. Are you going to still attempt to revisit shooting the wires and the ECE and BCM connections?