[eilex]

Hello

I'm the second owner of a VW EOS 2.0 FSI (1F7) from 2007, from the beginning It had some times a rought idle with engine kicks, the engine is always at 700 RMP at idle.

I want to ask if any of you have the same model, what's your engine idle RPM so in case mine is wrong I can try to change it.

I think the first owner maybe changed some settings of the engine to go on lower RPM but I want to ask you first to be sure before doing any change, if you can provide me also your "Idle Speed Adjustmen" value It would be helpfull too.

Thank you very much in advance!

From this point you can skip the rest of the post because it's all the things changed/checked on the car just in case some one has another point of view of the issue and could give it

The car has been at three different shops and no one has found what can be happening, it end up breaking the engine mounts and had to replace them last month. It was a whole month with an Audi technician doing tests to the car and nothing found.

Here is a list of the manteinance made to the car, but the problem was already there before doing this repairs:

• The EGR valve is new.
• All four ignition coils and spark plugs are new.
• The charcoal canister and purge valve are new.
• The engine mounts are new.
• The timing belt kit has been changed including the water pump.
• The oil has been changed.

Other things tested by the repair shops are those:

• There is no errors recorded.
• The engine has no leaks.
• The computer has been checked two times and it's fine.
• The engine timing has been checked and it's fine.
• The knock sensor has been checked and it's fine.
• The lambda sensor is fine.
• The injectiors and the injection rail pressure are fine.
• There is no leaks on the escape.

The engine goes fine for 15 seconds and then it suddenly shakes like if it was close to a small stalk and then it goes strange for a pair of seconds and then it happens again after a while. If I rev up the engine let's say 100 RPM more, 800 RPM in total, the problem dissapears but as soon as it goes as the engine goes back to idle speed (700 RPM) the problem comes back. Also when the kick happens it sounds on the escape like a small pop & bang (without the bang, but I think it could be the engine injecting more gas to recover from that mini stalk).

There is a situation where this problem doesn't happen, when it's really cold outside and high relative humidity (6ºC and close to 90% humidity).

 

[voxmagna]

The engine idle speed is preset by the ECU because it has to be controlled receiving inputs from sensors and fit different operating conditions of the engine. E.g when your air con compressor cuts in or your alternator load is high, the engine idle is compensated to hold the correct value which is about 900 rpm for my Tdi. Engine idle is not something that should be user adjustable because V.W have to meet stringent emissions criteria and of most concern is emissions performance in cities when engines can be idling a lot.

Just an observation, but IMHO repair shops that go around changing parts at your expense really aren't doing proper diagnostics work, or they aren't good enough to do it?
If idle speed is changing and can do this when the shop has their diagnostics connected they would see this in live data being read, but there is much more realtime engine data that can be examined. If they confirm the idle rpm changes, then there's a fault for them to fix. The first thing they and you should check is if the ECU software has been tampered with. A diagnostic scan at a V.W stealership will throw up a red flag on the screen if it has. They can confirm the number if 'Writes' to the ECU and if It's zero, then it's still stock.

When shops and many DIYers use diagnostics they tend to regard it as a quick way to tell them what's faulty. In cases like yours, there may not be a fault code logged but those using diagnostics should be able to look at real time measuring values and draw some conclusion, provided they are paid enough for those skills. If it's not a V.W shop using V.W compatible diagnostics then information may not show and they are trying to fix your car blind. At least with a V.W/Audi genuine shop they can call up their database of similar faults that might help them?

Your engine fault won't be solved by changing parts at random and hoping for a result. In fact, changing parts without evidence and a solution just shows how inexperienced your workshop technicians are and can sometimes muddy the waters and bring in other factors. Nobody has changed the accelerator pedal with its controller? I'm not saying that's your problem, but for somebody who want to try anything and everything at your expense, I might have expected to see it in the list.

You really need a technician working on your fault who understands how modern efi engines with electronic controls works and can apply the enhanced features of V.W compatible diagnostics to pin down what is happening when the fault occurs.

 

[eilex]

Hi voxmagna, thank you for your quick response

About the parts changed, the workshop was really kind, they didn't ask me to pay the cost of one month of work (smoke test, inspections of the other elements and the Audi professional) but they found some of those other problems and I asked them to replace the parts knowing that it wasn't the root cause.

I have found another person on Wallapop 😅 with the same car/engine a few minutes ago and he told me that his car starts at 1100 RPM and then goes down to 800 RPM idle without anything turned on.

In some test I did two weeks ago with VCDS I've seen on instant values that the target ECU RPM are 700 but the engine fails to mantain that speed when the vibrations start, I have also tested to press the pedal while I was looking at those instant values and with more or less 800 RPM target (because of a small press on the pedal) the engine RPM are stable.

If someone has the same engine please tell me if your's run at 800 RPM idle while nothing turned on, I know that there are alof of factors that can apply to that idle RPM but I want to know more about others idle RPM, my engine is the 2.0 FSI BVY.

Thank you again Voxmagna

 

[voxmagna]

Your idle rpm is held constant by the ECU but is in a 'Feedback control loop' reacting to engine sensors. The ECU is programmed to maintain the idle at a fixed value 800, 900 or whatever they designed it for. The ECU monitors sensor inputs and corrects the idle if anything sensed changes (whilst your foot is off the throttle. This automatic feedback loop only has so much range and if the engine conditions change and the control loop cannot maintain the same idle speed, it's because whatever happened is outside the normal engine behaviour and the range at which the engine will self correct. The auto idle control loop can exhibit another behaviour. When the idle cannot be controlled, most control systems will 'hunt' trying to find the balance. You can see this when fuel mixture ratio is bad. The engine runs lean, the ECU tries to put more fuel in to correct it, the idle speed changes, the ECU changes the fuelling and so this goes on because the normal operating point cannot be kept stable.

It's not important your idle is 800,900 or 1K, it's whether it holds its value or not. Yours isn't stable so there's a problem in the engine with what sensors are measuring or what the engine is doing when the sensors measure and the ECU cannot correct. So you can have a chicken and egg scenario - sensors producing out of range values or an engine fault which the sensors monitor but their feedback to the ECU cannot correct the drop in idle speed (caused by an engine running fault). Since you mention the onset of vibration, I would guess you have an intermittent engine fault not picked up by vcds and once this happens the ECU tries to correct the change in idle speed but cannot do so?

I know you say coil packs have been changed but a bad coil pack is a good example. Engine idle is working ok when all cylinders are firing correctly. Disable one cylinder by removing a plug connection and the engine vibrates but there's insufficient control to keep idle stable. Diagnostics is blind to coil pack problems because diagnostics only informs when there's a firing pulse not when there's a spark at the plug. Similarly, a bad valve or injector could bring on a problem but there's nothing in diagnostics measuring it. Knock sensors are the only way of detecting a bad cylinder firing, but at low idle speeds I doubt the knock sensor would be that sensitive? You posted a list of things done, I don't know how the average garage can check a fuel injector? I took mine to a Bosch specialist who used very expensive automated test kit to test and print a report for each injector.

You said rpm is stable with a small press of the pedal? Your pedal is drive by wire from its controller to the ECU and its potentiometers. VCDS has measuring blocks that can check for intermittent operation of the throttle pedal. As I said, diagnostics has many features to help you if you know how to use them and interpret the results.

You have to be careful assuming your car works exactly like others. ECUs are coded for whatever options are installed and no two ECUs are likely to have the same code and idle correction characteristics. A DSG car ECU will be different to a manual drive car. The one simple fact you have is you get engine vibration followed by a change in idle speed. You could try disconnecting a plug to get familiar with what the engine does on idle when it has a dead cylinder?

When people get remaps done they can get idle stability problems and why I suggested you confirm your ECU is still stock.

 

[Paddy OPlastic]

A pop sound might indicate some sort of vacuum build-up or, conversely, pressure build-up. You might try idling and unscrew the gas cap to see if the problem goes away. Similarly you might try to loosen the oil filler cap while idling. This will generally result in poor idle but if you hear pressure being equalised then you might have a clue. You don't say whether the PCV has been renewed. This has been redesigned and is also a cause of rough idling.

My 2008 TFSI idles at about 800 BTW but, like Vox, I doubt that's your problem.

 

[voxmagna]

Screaming noise from engine

G'day Got a 2013 Eos 2.0L turbo. Once the engine warms up, there's a horrendous screaming noise coming from the engine. It sounds like a wrecked bearing, but much louder. The odd the thing is If I lift the dipstick off its seat, remove the rocker cover oil filler cap or disconnect the crankcase...

www.vweosclub.com

 

[eilex]

Thank you Paddy and Voxmagna

When I took the car to that workshop that had the car over a month those where the first things they did, while I was explaining them the problems with the car he took the oil filler cap and put the hand on it, I remember that because I tough he was about to burn his hand.

At that moment there was intake air of unmettered air from this tube connection

(The image is not from my car just as reference, is from the same engine)

I will try your suggestions when I have time, anyway I didn't success finding a valid security/login code for the idle rpm adaptation of my engine.

Sorry for having VCDS screenshots on spanish.

(Engine unit)

On the test I made last weekend I've seen that if the engine is not warmed it starts at 1200 RPM, then it lowers it to 800 RPM and after a while it goes down again to 700 RPM and there is when the problem starts. I have some pics of what RPM was the unit targeting.

At 800 RPM on dashboard, at those revs the engine was perfectly fine.
(valor actual = current value, valor deseado = target value)

At 700 RPM on dashboard, the engine starts to has the problem but it's not constant and the current values goes under 650 and then the engine kicks up.
(valor actual = current value, valor deseado = target value)

There is something I didn't mention about the car, it cas some extra electric consumptions that I don't know if the car is smart enough to take into account while setting the idle RPM:

1. The radio is not the stock one so I'm not sure if I can asume that the car thinks there is no radio, it's an android head unit with IPS screen so I think it may consume more that stock radio.
2. The previous owner put a Pioner DVB-T Receiver under the codriver seat, which I think it's connected to the seat heat fuse because I have to replace it two times without even using it.
3. I also have asound system that can be hungry too with a switch to open the circuit and dissable the sound system entirely (when I took the car to the workshop I dissabled it and told them about that too) but it didn't seem to cause the problem because it happens without it and it happend since the first day just with the DVB-T and the radio.

I'll try to disconnect the radio, DVB-T and sound system too this weekend just to see if anything changes but I would like to know your oppinion about this, if that extra consumption may affect the car.

 

[voxmagna]

The radio is not the stock one

- power consumption will be small.

The previous owner put a Pioner DVB-T Receiver under the codriver seat, which I think it's connected to the seat heat fuse because I have to replace it two times without even using it

It's probably USB with very small power. If a fuse is blowing there must be a fault either with the power cable, a voltage converter to USB if fitted or the DVB-T module.
Only 3. might be an issue if you were burning a couple of hundred watts of audio at start up with Class A amps - but unlikely. If you think load regulation is an issue, try turning on the headlights and rear heater whilst idling just after starting.

Climate control and ac compressor aren't running so it's not them. What happened when you blipped the throttle as I suggested? AFIK 'valor deseado' is the value which the ECU says it wants and will equalise until 'valor actual' is reached. When they are not the same the engine is adjusting its running parameters. If it works like this and you run at idle then turn on headlights, defroster and aircon loads, I would expect valor deseado to increase fairly quickly as the ECU gets the load requirement, then the engine follows taking a bit longer to catch up and make valor actual equal?

When the oil cap is removed the whole balance of the engine is upset. If there is a problem with the PCV or hose connections the partial vacuum I tested for in the link I posted would not be constant and could even go positive pressure. I rely on measurements I make to tell me things, not guesswork.

Sensors giving feedback to the engine are an important part of this loop to maintain a constant idle rpm. At low idle they become more critical and even small air leaks or poor sensor performance will make it unstable. Read up on the exhaust sensors and what they do. For best efficiency, lowest emissions and smooth running the engine air and fuel supply is regulated to maintain a constant Stoichiometric ratio. Your diagnostics can do a lot more but I'm afraid you need to learn a lot or have an expert in EFi engine management drive diagnostics for you, perhaps start looking at the response behavior of your oxygen sensors? When rpm drops, what is the O2 sensor doing, is it slow and catching up, or is something else going on?

I still have a device I used on carb engines called a Gunson Colortune. It replaces a spark plug and gives you glass window to see into the combustion chamber as the spark ignites. Engine lag and poor response at idle was often a problem on carb. engines. By watching the colour change of combustion from orange (rich) to blue (weaker) and how fast it occured, you could diagnose problems with chokes and carb. diaphragms. Efi engines are a different game and whilst a Colortune is not dead yet for them, there are useful measuring blocks in vcds that can help you follow mixture balance and how the engine is responding. Pros with fire extinguishers also know about injecting Butane gas into an air intake snorkel to monitor engine response behaviour using diagnostics.

 

[pinto384]

I have the same problem with my Eos BVY. No engine light on and the same symptoms described. When cold starts at 1200rpm and then drops to 700rpm when the misfire and rough idle starts.