rikardo82

today I was at dealer and test drived car and transmission shifted normally at 7K immediately when gone full throttle still car jerking now they admit that probably transmission not at fault. All time there was P310B code now they claim it's gone but symptoms are identical as it was before... they told that they measured fuel pressure and that now it's in normal levels. it's audi dealer I don't know who else can help... they told tomorrow they will check again.

mkongsiri

Unfortunately even though a dealer is better equipped, your diagnosis is only as good as the tech that gets assigned the ticket from the service advisor. I worked as a Porsche/Audi/BMW tech years ago ago and knew dozens of guys back then. I'd say there were about 5 that were worth their salt. Nowadays, I don't let anyone do the diagnosis, just the work.

I'm not super familiar with the Audi arrangement as I worked on Mechanical CIS-E and the earlier Bosch injection systems. But it's not that terribly complicated once you understand the basics. Typically, system pressure is generated by the fuel pump, the fuel pressure regulator will limit the amount of pressure and return the fuel back to the tank. There should be a test port on the fuel line (typically a schrader valve) to the fuel rail. Your issue appears to be intermittent, consider trying this.

Ask them what the factory fuel pressure specs should be. If they can't or won't give you those values, go on ebay and order the factory manual for your car, I got mine for $12. Order a cheap fuel injection tester online ($20) and make sure it has the appropriate adapter for your test port. When you experience the driveablility problem again, connect your fuel pressure gauge and verify that the pressure is in fact dropping and that's what's causing this issue.

Sure is alot cheaper than paying the shop rate for them to learn how to diagnosis injection issues.

rikardo82

this problem with fuel pressure seems is only when driving car full throttle then is it possible to measure fuel pressure while driving car? Although now audi dealer claim that error code does not appear anymore and fuel pressure is ok. I will ask them then about values and did they tested when car was running full throttle.

Before repair after car was jerking it always gave this P310B error code now they told it does not appear anymore. They told that fuel pump is Ok as well filter they told very unlikely is bad. So what else could be wrong? ECU maybe??

FormulaElement

How many miles are on you car?

Can you better explain this twitching... Does the RPM stop and not continue to climb for a short time then continue then stop again? I feel that if it's the fuel delivery it wouldn't completely stop the engine from climbing, but just slow it down... Although I'm no expert.

Maybe the seller messed up replacing the high pressure pumps? Did he do it himself or at a shop?

Invest in a VAG-COM please! It would help us so much more in figuring out what is going on. To be honest it really could be almost anything...

rikardo82

it is 135K miles here is video of problem
https://www.youtube.com/watch?v=ibpQ...ature=youtu.be
after ~70KM/h problem start. High pressure pumps were changed at audi dealer. Yes it does not stop from climbing RPM but just slow down if I keep going it eventually reaches 7K RPM gets in next gear and continue going.

How much this VAG-COM software cost? I have laptop with OBD cable. But in this situation it would not help because as dealer told there are no errors at this time...

FormulaElement

Its around $300 dollars. It doesn't use a proprietary OBD cable, it uses one that links with VAG's interface so it can access much more car information. The cable also includes activation of the software which is free... The VAG-COM will tell much more than errors, it will give a lot of engine and trans information that you can log and create a graph while driving.... Not sure what all would help in this situation but i will take a look what it can log tomorrow...

Im really surprised it doesn't throw a code... My A6 V8 does the same thing if i shift it manually at about 3.5k RPM with low throttle, but doesn't last very long... It doesn't do it when i floor it tho..

rikardo82

it would be very useful does it work only for audi or other cars I also can test? Probably I will sell this car so don't want invest $300 if it's only for Audi. Where can I buy it for $300??

Error code P310B was before repair in Audi dealer (where they changed low pressure fuel sensor and some fuel valve for $650) now they claim it does not appear anymore but maybe they just telling it to justify their expensive repair which at this time for me seems useless... because problem is still same.

rikardo82

I got a call from dealer that again when engine is cold 4 and 8 cylinder got misfire they cleared error went for test drive and car run perfectly again... so again I have feeling all that big repair was useless all this situation is identical as it was before...

rikardo82

I just called previous owner he told that he washed engine 2 months ago then similar problem was he changed coil pack for cylinder 8 then again sometimes that problem was. After washing engine he drive some 350KM. So it looks like problem started after washed engine. What part could be damaged when washing engine???

FormulaElement

Any and all of the electronics... Also if it was hot, i don't even want to think of the horrors that could of happened with water hitting these engines at operating temps.....

VAG-COM can be used like your regular OBD scanner to any car, but will be able to go into in-depth scans on all cars that are manufactured by the VW auto group... Audi, Porsche, Lamborghini, Bentley, VW, Skoda, Veyron....