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Discussion Starter #1
Hi all,

I have an annoying fault on a 2008 S5

Whilst driving along at a sedate pace in 6th gear, if I press down on the accellerator to accellerate, I get a small hiccup at 4000 rpm and the EPC licht comes on resulting in reduction to 50% power.

I pull over at the earliest opportunity and switch off the engine and immediately restart and the EPC light clears and I can go on without any problems.

The EPC light may not come back on again for a few weeks or it could be days - totally random, but always @ 4000 rpm and only in 5th or 6th gear.

Can anyone shed any light on this as the dealer says they cannot find any fault codes and my warranty is about to run out. :hissyfit:

Regards

Simon
 

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Maybe they're not looking in the right place for the fault codes. If it's cleared when you restart it wouldn't be an active fault code. Isn't there a way for them to look in a log/history of previously active fault codes? I could be wrong.

Sounds like it could be carbon build up?
 

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This same situation has happened to me, but after a restart, it cleared and its been months since then. Do you drive on dirty roads?? This fault code came on after I drove a half mile down a rough dirt road.

Let me know if the dealer figures it out.
 

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I dont know the answer to this one, but do make sure the dealer has got this complaint documented, I would expect Audi to honor any warranty claim if it fails a bit outside the warranty period.

Anyone near you with VagCom?
 

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Discussion Starter #5
It happens on motorways and dual carriageways when the road ahead clears and I can put my foot down.

I don't drive on unmade roads - it is my pride and joy after all !!

I have taken it to an approved Audi dealership in Oxford

On other forums other owners have found split vacuum hoses or faulty air mass meter (sensor) may be the culprit

It is just typical, whenever you take your car into a dealer their apprentice mechanics seem incapable of diagnosing a problem !!!
 

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Discussion Starter #6
Just done an experiment on a 300 mile drive today

It appears that the EPC light only comes on if when I am in 6th gear driving along steadily at around 3000 rpm and then flooring the accelerator at which point when I reach 4200 rpm there is the charactistic hiccup and the EPC light comes on and power reduced by 50%

If I gradually press the throttle (i.e. not floor it) the EPC light does not come on.

It feels like it could be something to do with the throttle

Any ideas ?

Regards

Simon
 

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Do you have a manual or S-tronic?? Could be gearbox related, and from my experience both with my car and reading the forum both manual and auto from Audi can be a bit shoddy.

Also, 4000 RPM in 6th in an S5 must be pretty brisk!
 

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Discussion Starter #8 (Edited)
I have a 6 speed manual and 4000 is around 120mph

I have read on other forums that there is a problem with the throttle rheostat

Does this make sense ?

Regards

Simon
 

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Discussion Starter #9 (Edited)
Just got back from Audi Dealer and managed to demonstrate the EPC fault to their master technician - they then got a fault code relating to a low pressure fault on the fuel rail.

The DTC code is as follows:

00135 P0087 fuel rail/system pressure too low

Possible causes


- Fuel pressure sensor harness is open or shorted
- Fuel pressure sensor electrical circuit poor connection
- Faulty fuel pump
- Blocked fuel filter
- Fuel line restricted
- Faulty fuel pressure regulator
- Faulty fuel pressure sensor

Now since it ONLY happens when I am on full throttle in 6th gear at 4200 rpm and does not happen in any other gear or when I apply half throttle in 6th gear at 4200 rpm

Which of the above possible faults is most realistic ?

Regards

Simon
 

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Discussion Starter #10 (Edited)
EPC fault caused by supermarket petrol - shot spark plugs & damaged HP fuel pumps

I took the car to Revo Tecknik in Daventry and they immediately found that all spark plugs were shot and badly damaged and the retard was running at over 15 degrees. They fitted new spark plugs and drained the fuel tank and refilled with Shell V-Power - they claim the car is running a million times better now.

On further investigation they road tested the car connected to a laptop and subjected the engine to maximum torque in 6th gear - they have found that the one or both high pressure fuel pumps are under performing thereby starving the engine of fuel at maximum load, which subsequently triggers the EPC light.

The problem in their view is caused by prolonged usage of supermarket 95 RON unleaded petrol. Apparently Tesco Momentum 99 RON is even worse due to the crap they put in it. What I didn't know was that you should only use 95 RON as a last resort - No-body told me that !!

In Germany they don't have the crap grade fuel that is sold by UK supermarkets and as a result, Audi are now reducing the compression ratios on all UK spec cars due to the widespread usage of supermarket fuel.

Revo Technik recommend only using Shell V-Power, BP Optimax or Total Excellium.

The car is in with the main dealer on Tuesday and hopefully they will replace the fuel pumps under warranty. Also, the spark plugs were damaged by the excessive retardation caused by low grade fuel - they should last 40,000 miles which probably explains why the master technician at Oxford Audi did not even look at them - the car has only done 22,000 miles so I will be asking for these to be covered under warranty too.

I just goes to show that the calibre of mechanic at Audi Main Dealers is not that great and unless the on-board computer gives them an exact fault code, they are incapable of diagnosing a fault and fixing it - this fault has been happening since August 2010 and Oxford Audi have had my car several times to unsuccessfully diagnose & fix the fault - Revo Technik diagnosed it in 45 minutes !!

Guess where I am getting my car serviced in future !!

Regards

Simon
 

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^^^ honestly I am not at all convinced by that from Revo.
Some of it is plausible, some of it is wrong, some of it looks like plain BS.

Why, with the dealer having witnessed the problem, did you feel the need to go to an external outfit if the car is under warranty - did the delear refuse to fix it?
 

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Discussion Starter #12 (Edited)
I am scheduled to go back to Oxford Audi on Wednesday 30th for expensive diagnostics which they wanted to charge me for.

I have a friend at Revo Technik who did the work for free !!

I just don't have any faith in Oxford Audi to find the fault - remember my car has been in and out of their workshops several times since last August and they could not find the fault let alone fix it.

At least now have a solution to what needs doing - replace both fuel pumps under warranty.

Also since having the new plugs fitted and running with Shell V-Power, the car runs loads better and the EPC fault is now coming on in 5th gear much more readily - the HP fuel pumps cannot cope with keeping up the pressure running 8 bar below what they should run at.

Regards

Simon
 

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Hi
I have a 2009 A5, V6 3.2 with less than 50k miles on it and the EPC light turned on while driving at 180 kph, at the same time the engine stalled and a feo seconds later, the engine exploded.
Unfortunately the warranty had expired but the Mexican Audi Dealer, granted me a courtesy of 70/30 on parts, they had to change the whole engine but when they tried to start the car, the transmition was "parked" and they had to change it too.
After three months finaly I have my car back, I drive it for less than an hour, and the EPC light went on again, accelerating up to less than 4000 RPM, this time appeared a message saying that I should not exceed 4000 RPM and a sign with a tachometer.
I stopped immediatly to call the dealer, he told me to send him the car back but when I restarted the engine both warnings went off. I drove a couple more miles and stored the car. I do not know what is happening, this is not my first and only Audi, and I have never had such an issue before.
 

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Hi guys, I know it's been a while since this post was updated, but did any of you happen to replace the fuel regulator on your car by any chance? I'm thinking of giving it a shot, but can't find any instructions on-line. Any help would be greatly appreciated.

Thanks,

Greg

09 S5
 

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If it is a bad fuel issue and you are replacing all those parts don't leave out the fuel injectors-no doubt they are clogged and fouled as a result of shite fuel. that can also give you an epc light as well as poor high performance
 

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Thanks for the quick response. Fortunately, I was told about the "Top-Tier" fuel and have only ever used Shell's highest grade full. I received the P2293 error code and have experienced the "limp" mode when hitting a certain RPM. The car will sputter a little when I first start it in the morning, but otherwise there have been no other issues. It has kept me from breaking the speed limit (not much fun though). I'd like to replace the regulator myself, but can't seem to find it.
 
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