cp4 failure or something else?

[jmswltn]

Not quite the best place to post I guess but this is the car the engine came from.

My CJAA swapped B8 Q5 suddenly lost high fuel pressure turning into a parking lot today. Both lift and intermediate pumps run and build pressure to ~<15000hpa showing in VCDS. I installed a cp4 disaster prevention kit 2 days ago and put 75 miles on it since. There was some material (aluminum I assume) on the gasket of the metering valve but no shavings that I could see. I have had no related codes and it ran great till it died but now showing the p0087 fault code. do these cp4 fail just that suddenly or should I look for something else? It's always ran good without sputtering low power or noise.

 

[lemoncurd]

CP4's do fail that suddenly.

Sadly, due to the nature of how close this failure occured after you installed the "disaster prevention kit" I am inclined to point fingers at that as the culprit.

You're not the first to have had a CP4 die after installing that kit, and I don't think you'll be the last.

Imo, those kits are more harm than good.
The CP4 is fine for reliability providing you do 2 things:

1: Never run it out of fuel
2: Change the fuel filters routinely, and on schedule.
Honorable mention: not mess with the fuel lines, low or high pressure, as it can introduce air into the system and people RARELY do a proper bleed after introducing the air.

Also, 15000hpa to psi is like 2 psi.. you need considerably more head / feed presure to the CP4 than that.
To my knowledge the CP4 takes something like 100psi of feed/head pressure.

 

[jmswltn]

1: Never run it out of fuel
2: Change the fuel filters routinely, and on schedule.

I got the engine a 90k miles and have put about 15k on it since. I have been very strict on priming the fuel system before cranking, refilling at 1/4 tank as well as always having lubricity additives (hot shot etc..).
I have verified cam and crank speeds during cranking to rule out not actuating the control valve do to no cranking detected. Unless the online converter is incorrect 15000hPa is 217psi but mine is more closer to 12900, still within spec. The post filter for the prevention kit as well as the canister fuel filter were both clean and free of any metal debris.
If the pressure control valve fails will it not build pressure?

I noticed you have the uprated pressure sensors listed in your signature, thank you for that. Did you remap your files to suit and if so do you have the sensor values to share? I found these linearization values to go off of for the fuel sensor but I don't know if they correspond with the VAG as they are from a BMW https://drive.google.com/file/d/12ieuTHLZf0ffDoObz9hQxGxjlcS22scg/view?usp=drive_link

 

[lemoncurd]

ah okay, it looks like your unit conversion is correct. google's unit conversion showed me the wrong number entirely. 217psi is what i got too after going to a different website

i dont have any info on the remap portion of fitting a higher pressure fuel sensor, though i do know it isnt required unless youre going to increase your fuel pressure.

i do believe if the pressure control valve fails, it would result in a no start / no pressure situation. though i would think this results in a DTC being raised..
are you able to scan your vehicle with VCDS and post the auto-scan?
(nice job on the swap BTW)

 

[jmswltn]

i dont have any info on the remap portion of fitting a higher pressure fuel sensor, though i do know it isnt required unless youre going to increase your fuel pressure.

I plan on increasing it as far as I can safely

i do believe if the pressure control valve fails, it would result in a no start / no pressure situation.

I managed to find a spare used one locally but it did not fix the issue

though i would think this results in a DTC being raised..
are you able to scan your vehicle with VCDS and post the auto-scan?

it will throw a dtc if unplugged, I can attach a scan but it doesn't show the low pressure error as I deleted it.

one thing to note is I am using the petrol in tank pump for a lift pump. It is still definitely working, I'm not sure on the flow rate but it has to be a couple gallons a minute by how fast it started to fill a gallon jug

The forum altered my engine code

Thursday,08,August,2024,16:57:45:03653
VCDS -- Windows Based VAG/VAS Emulator Running on Windows 11 x64
VCDS Version: 24.7.0.0 (x64)  HEX-V2 CB: 0.4643.4
Data version: 20240715 DS356.3
www.Ross-Tech.com

Workshop Code: 210 01369 040505

VIN: WA1LFAFP0BA******   License Plate:
Mileage: 296100km-183988mi   Repair Order:



--------------------------------------------------------------------------------
--------------------------------------------------------------------------------


Chassis Type: FP-AU48 (8T0)
Scan: 01 02 03 05 08 09 15 16 17 19 2E 36 42 46 47 52 53 55 56 62
          69 6D 72 77

VIN: WA1LFAFP0BA******   Mileage: 296100km-183988miles

01-Engine -- Status: OK 0000
02-Auto Trans -- Status: OK 0000
03-ABS Brakes -- Status: Malfunction 0010
04-Steering Angle -- Status: OK 0000
05-Acc/Start Auth. -- Status: Malfunction 0010
08-Auto HVAC -- Status: Malfunction 0010
09-Cent. Elect. -- Status: Malfunction 0010
15-Airbags -- Status: OK 0000
16-Steering wheel -- Status: Malfunction 0010
17-Instruments -- Status: Malfunction 0010
19-CAN Gateway -- Status: OK 0000
2E-Media Player 3 -- Status: OK 0000
36-Seat Mem. Drvr -- Status: OK 0000
42-Door Elect, Driver -- Status: OK 0000
46-Central Conv. -- Status: Malfunction 0010
47-Sound System -- Status: Malfunction 0010
52-Door Elect, Pass. -- Status: OK 0000
53-Parking Brake -- Status: Malfunction 0010
55-Headlight Range -- Status: OK 0000
56-Radio -- Status: Malfunction 0010
62-Door, Rear Left -- Status: OK 0000
69-Trailer -- Status: OK 0000
6D-Trunk Elect. -- Status: OK 0000
72-Door, Rear Right -- Status: OK 0000
77-Telephone -- Status: OK 0000
-------------------------------------------------------------------------------
Address 01: Engine (J623-****)       Labels:. 03L-906-019-CAG.clb
   Part No SW: 03L 906 022 RM    HW: 03L 906 019 AL
   Component: R4 2.0l TDI   H34 9978 
   Revision: 25H34---    CVN: 8869BF65
   Coding: 1A2A0012043602080000
   Shop #: WSC 01369 210 40505
   ASAM Dataset: EV_ECM20TDI03L906022RM A02008
   ROD: EV_ECM20TDI03L906022NP.rod
   VCID: 015F8B554189EE5250D-8054
   VINID: 9D105C5915A00124401461400CCE54019A

No fault code found.
Readiness: 0 0 0 0 X

-------------------------------------------------------------------------------
Address 02: Auto Trans (J217)       Labels:| 0BK-927-156.clb
   Part No SW: 8R0 927 158 E    HW: 0BK 927 156 N
   Component: 0BK 20TFSIRdW H08 0009 
   Revision: --H08---    CVN: 654469DA
   Coding: 001111
   Shop #: WSC 06335 000 00000
   ASAM Dataset: EV_TCMAL551211 001013
   ROD: EV_TCMAL551211_001.rod
   VCID: 3FDB4DAD77FD58A2669-806A

No fault code found.

there are various other codes for stuff that was disconnected during a suspension rebuild and tail light swap. after deleting these it still doesn't start.

 

[lemoncurd]

im out of idea's :/

 

[Speedmaster_102]

CP4's do fail that suddenly.

Sadly, due to the nature of how close this failure occured after you installed the "disaster prevention kit" I am inclined to point fingers at that as the culprit.

You're not the first to have had a CP4 die after installing that kit, and I don't think you'll be the last.

Imo, those kits are more harm than good.
The CP4 is fine for reliability providing you do 2 things:

1: Never run it out of fuel
2: Change the fuel filters routinely, and on schedule.
Honorable mention: not mess with the fuel lines, low or high pressure, as it can introduce air into the system and people RARELY do a proper bleed after introducing the air.

Also, 15000hpa to psi is like 2 psi.. you need considerably more head / feed presure to the CP4 than that.
To my knowledge the CP4 takes something like 100psi of feed/head pressure.

So you don't recommend the disaster prevention kit? I respect your opinion as you are quite a knowledgeable guy here when it comes to TDIs. I was strongly considering buying the kit as I recently completed the timing belt in Nov 2023 and I was hoping to install the kit to get me by until the next timing belt replacement.

 

[jmswltn]

I was strongly considering buying the kit as I recently completed the timing belt in Nov 2023 and I was hoping to install the kit to get me by until the next timing belt replacement.

Even though I am having trouble after installing mine I still recommend installing it. These kits supply clean fuel to the top of the pump separating the rotating assembly and the potential debris. As long as you have good connections, clean fuel lines and purge the air out all the way you will be fine. I have a clear fuel filter on the post filter return line to the tank to see if all the bubbles are out during purging. I have found the lift/in tank pump doesn't completely purge the lines on the engine and the auxiliary pump should be used as well.

 

[lemoncurd]

So you don't recommend the disaster prevention kit? I respect your opinion as you are quite a knowledgeable guy here when it comes to TDIs. I was strongly considering buying the kit as I recently completed the timing belt in Nov 2023 and I was hoping to install the kit to get me by until the next timing belt replacement.

i personally would not recommend the disaster prevention kit.

i see it so frequently on the forums that something goes wrong either during the install or shortly there after.

imo, the risk outweighs the benefit.
the failure rates of the cp4 are quite low, especially for 2012 and newer.
like 1% of something, maybe less.

 

[turbodieseldyke]

I wonder if the extra filter + whatnot disrupts output flow & creates back-pressure the cp4 can't handle.

 

[jmswltn]

I'm going to have to say the pump did fail. After additional diagnostics and cranking I did find some more aluminum sludge under the bypass block. I remember thinking to myself about how quickly it cranked over and that the pump must be healthy. I still didn't find any metal in the filter housing, rail, lines or top of the injectors which is bizarre. Either way the CP3 should be here in a week or 2. I'll probably will plumb in a low micron filter to catch anything that may have entered the tank. The petrol pump in the tank has a filter in it already so I'm on the fence about adding another.

 

[Speedmaster_102]

I'm going to have to say the pump did fail. After additional diagnostics and cranking I did find some more aluminum sludge under the bypass block. I remember thinking to myself about how quickly it cranked over and that the pump must be healthy. I still didn't find any metal in the filter housing, rail, lines or top of the injectors which is bizarre. Either way the CP3 should be here in a week or 2. I'll probably will plumb in a low micron filter to catch anything that may have entered the tank. The petrol pump in the tank has a filter in it already so I'm on the fence about adding another.

If you plan on running a CP3, I don't think you need to plumb in anything else bc my understanding is that if a CP3 fails, it will be contained within the CP3 pump.

 

[jmswltn]

If you plan on running a CP3, I don't think you need to plumb in anything else bc my understanding is that if a CP3 fails, it will be contained within the CP3 pump.

While that is true I am more worried about the injectors themselves getting clogged from any scrapings that may have gotten by before the return line filter kit was installed. I never saw any debris in the filter or housing but the aluminum looking sludge I saw under the metering valve leads me to believe something may have gone somewhere. I'm still not certain the cp4 failed, if it did it was the least climactic failure ever. I had good power and it started quicker than most gas engines I have had all the way up to the point it shut off. All the images I've seen on on line the filter was full of steel and aluminum shavings.