Although not very satisfying, a good video and an important lesson.
I've been thinking about how there is supposed to be no hash in the fuel rail pressure sensor PID, and how it ran better but not great with the resistor.
Is it possible that a worn cam lobe
(Or associated mechanical failure of the high pressure pump) could be causing fluctuations in fuel pressure that the fuel pump driver cannot compensate for.
So you load it with with a constant resistance, now it's not trying to make up for mechanical wear, and is at least providing STEADY fuel pressure, even if it isn't up to spec.
Yay, another multi-part Premium series! :woohoo: These are the best.
I don't want to say I like to see Paul struggle, but... I like to see Paul struggle? :blush: :lol: 'Cause at times, diagnostics ARE a struggle! And I really like how these videos show that.
Did it seem weird to anyone how the fuel pressure data PID kept changing, even though the resistor was installed? Makes me wonder if that PID, and the sensor that got bypassed, are different sensors. :blink:
It will be interesting to see if it is a pump cam issue, in Europe some VW diesels used a not dis-similar system "Pumpe Duse". In PumpeDuse each injector had its' own integral camshaft driven pump. The Pumpe Duse engines were very dependant on the use of the correct specification of engine oil to protect the cam. However the dealers should have spotted any cam wear when they fitted the new pump.
However the resistor test has me wondering if perhaps we are not looking a wiring harness issue I wonder if it would be worth scoping the pressure sensor.
" We're trying to plug a hole in the universe, what are you doing ?. "
(Walter Bishop Fringe TV show)
A friend made this for me. Had an Audi S5 kick my ass all week and this is a still shot from a video I shot when I finally figured out what it was haha thanks bro!
Hey Paul, loved the vid. This type of video is definitely the best type. At the end when you were talking about testing the high pressure pump with out removal as there will be times when you can't remove it. I thought these 2 vids would help with that comment. I use this test alot on high pressure petrol and common rail diesel as the principal is the same and it works
You can also see a faulty fuel pressure regulator in the high fuel pressure waveform on a WOT and start up test, if you know what to look for. I even have some diesel known good and bad pico files I can share with you if you think it might help? Cant wait for episode 2. Thanks again
have had a few problems with cam lobe wear (very bad ) on all fsi engines
check to see if metal particles in the fuel ? that will be the H/P pump breaking up!
magnet in the fuel tank sender hole or cut the filter open and inspect
Hi Paul.
As i remember Audi has a TSB call "2016931" that addressing these symptoms on a 4.2L FSI (GDI) (DTC P0087, P0088 and P310B)
This can be a faulty pressure relief valves in the rail or a blocked return to the low pressure side.
A too high rail pressure of 140 bar (2030.52 psi) can prevent the start release... Due to the hot engine, the fuel expands after stopping the engine and increases the fuel pressure so far that the engine control unit can block engine start. In this case, allow the engine to cool down and then try to start the engine. If this is possible, check the pressure relief valve and the return in low pressure.
A friend made this for me. Had an Audi S5 kick my ass all week and this is a still shot from a video I shot when I finally figured out what it was haha thanks bro!
Waw I really enjoyed part 2!! An engine mount??? :woohoo: Paul mentioned different reasons on why a faulty solenoid would turn off the high pressure pump. But still not 100 % sure. Someone has to know so shoot if you do!
Dylan wrote: Waw I really enjoyed part 2!! An engine mount??? :woohoo: Paul mentioned different reasons on why a faulty solenoid would turn off the high pressure pump. But still not 100 % sure. Someone has to know so shoot if you do!
From my buddy Tommy Wolfe of Positive Lead Diagnostics. The VW Tourage is the only model that uses this same 4.2 engine and they have the same engine mount solenoids but DO NOT disable the high pressure fuel pumps when they fail. They just set a code and MIL.
So even my VW experts were dumbfounded by this reaction.
Good job on finding the problem! It was certainly something out of left field!
I doubt the engine mount solenoid is used as a sensing element, i.e. the current flow indicating load. I suspect that the computer expects a certain range of current to be drawn and if it is outside that range a fault is assumed and the driver should shut off for the solenoid. It does not seem like there is a logical reason to also shut off the high pressure pump so that would suggest a programming error. Does Audi have a list somewhere of firmware updates for the engine computer? It would be interesting to see if a problem with the mount or pump is listed.
