Okay, I’ll persevere. I’ll assume the table does not provide enough information.
Mismatched leak off from injectors on 2015 Audi TT TDi.
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Yeah, Bosch is one of the most counterfeit brands in the automotive world, so much so that even legitimate supply chains have been and probably still are compromised. Also not sure what "the bay" means? If it's a store, I'm not familiar with it.
I'd recommend going to the dealer and purchasing a fuel pressure regulator directly from them. Yes, you'll pay more, but you're guaranteed it won't be a counterfeit.
I'd recommend going to the dealer and purchasing a fuel pressure regulator directly from them. Yes, you'll pay more, but you're guaranteed it won't be a counterfeit.
Definitely don't trust it. Go buy from the dealer.
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You can take that as it is written.
Your interest is your interest - That will have to suffice !
This is the graph of pressure vs RPM during the road test, so the main spike was early in the drive but higher up the graph…
This one is during the test drive, so shows in seconds when it happened but not at which RPM…
I’m now looking into comparisons between real and fake Bosch FPRs, but not found much online, so I’m going to remove it and compare them closely.
This one is during the test drive, so shows in seconds when it happened but not at which RPM…
I’m now looking into comparisons between real and fake Bosch FPRs, but not found much online, so I’m going to remove it and compare them closely.
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You are all over the place with this !!
You may get lucky and fix it but if you dont find that luck you are making the car harder to fix !!
The FRP Rail Pressure Regulator is a common failure on these engines, however everyone that I come across will cause problems at Idle and will drive ok otherwise.
There is a way to conclusively test that FRP. It involves
- A PWM Generator sufficiently rated to be able to drive the IMV and FRP
- A Decade Box that can emulate both the FRP & the IMV
With those tools I would force that pump from Idle Pressure right up to 1800 bar or close to using an oscilloscope to measure how many turns of the engine it took to achieve max pressure. At some point the Engine should see max pressure and shut it down to prevent destruction.
Removing any component to test it is a big NO NO !! Just plain wrong !!
Same as your injectors and leak off tests - All wrong!! Useless Test Procedure !!! Waste of Time !!!
You DO NOT have a problem with the car stationary and low engine load regardless of RPM !!! So why test in those conditions ???
All your measurements MUST be captured at the time of failure with an overlap either side. Then the Failure sticks out like a saw thumb !!
First we need to measure leak off in millilitres. Nothing stopping you taping the 4 bottles to the windscreen and driving it to failure ??
What you need is a pressure transducer on the return flow and another on the HP Side. A flow meter and another transducer on the LP side and then drive it hard to failure.
There is no better way of solving P0087 and get a first time fix - Job done !!
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I would guess more fakes than real ones and worse still no way of knowing which is which ?
Price is always the giveaway half the time - It is perfectly possible to mark up the "fake" to proper money to give it the legitimate look !!
Thanks for taking the time to reply in such depth.
You are all over the place with this !! - You asked for a graph and I posted them
Regarding the FPR, it is new and as its originality is suspected I was going to take it off to physically compare to the original-not test it.
I don’t have the PWM generator, decade box etc so will have to see if it is feasible to purchase, get a specialist look at it or simply find a confirmed genuine FPR.
You DO NOT have a problem with the car stationary and low engine load regardless of RPM !!! So why test in those conditions ???-The graphs are from a test drive, not stationary. The reason RPM are so low is because it wouldn’t rev past that after the ECL showed on the dash.
Same as your injectors and leak off tests - All wrong!! Useless Test Procedure !!! Waste of Time !!!-The leak test is from the Audi workshop manual to test by cranking a non starting vehicle. I replaced the injectors because they failed this test and the car now runs.
Taping the bottles to the window and driving what to failure?
The divergence between actual and specified are concerning, and the fact that one is positive while the other is negative is puzzling.
-Uwe-
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We are 4 pages in and still nowhere fast.
P0087 it seems is not an easy thing to cure ??
Your dealer will likely replace everything with genuine bits and, of course, wont go far wrong. They wont have the tools, training or knowledge to get "root cause" diagnosis. That regime does not go that deep.
Any Engine that throws a P0087 under load will pass every test at Idle - Testing that way is futile.
Your graphs only confirm P0087 is there. So little diagnostic value.
I asked for the Graphs in Post #17 Where the engine would not start.
RPM vs Rail Pressure Graph is a valid request for a Common Rail Diesel that cranks but will not fire.
Now that it starts those graphs are not required. No Value !
I would be surprised if FPR would be the cause here.
You will be lucky to find a specialist who will have the depth of knowledge or tooling to test these components whilst still in the car, right down to Root Cause. They are out there though but few and far between.
As for a confirmed FPR - Where will you get that ??
Something tells me you have an injector "letting go" under load ? I would be looking very closely at CKP and O2S1 for that !
P0087 it seems is not an easy thing to cure ??
Your dealer will likely replace everything with genuine bits and, of course, wont go far wrong. They wont have the tools, training or knowledge to get "root cause" diagnosis. That regime does not go that deep.
But your Leak off tests were whilst stationary - So not properly tested at point of failure. Wrong Temperature, Wrong Load, Wrong Pressure ....
Any Engine that throws a P0087 under load will pass every test at Idle - Testing that way is futile.
You asked for a graph and I posted them
Your graphs only confirm P0087 is there. So little diagnostic value.
I asked for the Graphs in Post #17 Where the engine would not start.
RPM vs Rail Pressure Graph is a valid request for a Common Rail Diesel that cranks but will not fire.
Now that it starts those graphs are not required. No Value !
I would be surprised if FPR would be the cause here.
You will be lucky to find a specialist who will have the depth of knowledge or tooling to test these components whilst still in the car, right down to Root Cause. They are out there though but few and far between.
As for a confirmed FPR - Where will you get that ??
The Car !
Something tells me you have an injector "letting go" under load ? I would be looking very closely at CKP and O2S1 for that !
Ah well, at least I know how to get graphs now.
Where would I get a confirmed FPR you ask? Directly from Bosch I’d say is the only sure way, unless TPS/VAG can be trusted.
I looked at the FPR I bought and just noticed the date printed on it is 13 May 2025, so if that’s meant to be the DoM it’ll be fake as I received it on the 9th.
I’ll look into what I’m meant to note with CKP and O2S1 next, thanks. Hopefully it’s not an injector as they are newly refurbished items.
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First I dont think Bosch will sell it to you directly. They will have resellers.
TPS VAG is the official source.
Yep, that's a "smoking gun" for a fake part. Despite Sheldon's insistence that the FPR likely isn't the cause, I recommend immediate replacement with a genuine dealer part. That will at least eliminate a known issue with a fake part, and narrow down the troubleshooting required if you still have issues.
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I didn’t log the temperature but it had been driven for under 10 minutes at this point. Don’t shout at me for not being exact.
Next is to replace the FPR with genuine before going further.
Yep, I’m on it. That’s my next port of call. Thanks.
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In that case please drive it when fully warmed up. Graph Fuel Pressure Desired and Actual as you did before and post that. It would be a big help.
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Of course be sure to get the fault to occur as you did before.
Will do. Do you need to see the actual temp logged or just that I warm it up first?
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