[amartya_bhp]

Originally Posted by veedub89

So much water out of the exhaust is astonishing!

Who washes your car? Hired a chap?
Is he taking the garden hose at full pressure and shoving water inside the exhaust to clean it?

Water is seen coming out from the exhaust almost always after a good wash. But so much water makes no sense. Ties in with your other observation that all this happens in the morning only. Because after all the water has come out, there is nothing fouling with the car and it's internals.

I don't wash my car daily, I get it pressure-washed once in a while. In fact this problem happens everyday in the morning only in the first start of the day!

Originally Posted by ajs85

Lately, I'm also facing a somewhat similar issue, with hard acceleration and kick down the car giving a hard jolt. The diagnostic error shows a misfire in cylinder 2, this started after I got the spark plugs and coil changed. Tried swapping coils but still had the same issue. The fuel always used is RON 95 and try to stick to only a few of the marked COCO bunks in Delhi NCR.

Done so far:

• Checked and changed Coils and spark plugs
• Checked pressure of fuel pump via diagnostic readings
• Checked mounts (just in case to rule out any broken mounts)
• Checked and got fuel lines and throttle body cleaned

The car is C200, W204, 2014 with 55k on the clock. Would surely like to get feedback on what AUDI diagnosed with your car. The guys at Mercedes are asking me to now change the fuel pump assembly (both of them are located in the fuel tank)

So sorry to know of your problem, even though it is unpardonable, such issues can happen sometimes in an old car, but mine is Sept 22 registered, and has run only 8000 km

I will let you know the outcome, hope that helps you work with MB guys!

[el lobo 6061]

Originally Posted by amartya_bhp

Off late though, my steed is in the garage with a strange fault that is still undiagnosed by Audi (they are trying various things) and that is why I am putting this up here for your comments/feedback/suggestions. Hopefully, the experience in this forum will help in getting the problem resolved.

Originally Posted by ajs85

Lately, I'm also facing a somewhat similar issue, with hard acceleration and kick down the car giving a hard jolt. The diagnostic error shows a misfire in cylinder 2, this started after I got the spark plugs and coil changed. Tried swapping coils but still had the same issue. The fuel always used is RON 95 and try to stick to only a few of the marked COCO bunks in Delhi NCR.

I guess this could be due to E20 Petrol (20% Ethanol).

Since VW/Skoda/Audi have been selling only E10 compatible petrol engines till date when E20 has already started rolling out in major metro cities from December 2022.

Read this news article:
E20 petrol will be available in India by December or January: Puri

Only BMW was selling E25 compatible petrol engines.

Also effect of E20 petrol will be more on E10 Petrol engines as compared to using E10 petrol in non-ethanol compatible petrol engines.

High compression petrol engines need proper fuel else they are not gonna function well.

[Jeroen]

Given the symptoms you describe, poor or no starting when cold, I doubt very much it is anything like coils or so.

In order to diagnose something we first need to have an understanding of how the start sequence of this car actually works. Then that sequence needs to be validated. It’s been awhile since a worked on an Audi, but all modern cars have more or less the same system.

When you turn the ignition and certain pre conditions are met (e.g. transmission in neutral) the engine starter or rather the Bendix will engage. During the initial rotation of the engine no fuel or spark is fed to the engine. The ECO (or perhaps another computer, such as the PCM) needs to see a signal that the engine is turning at the required RPM. It will also need to determine the starting conditions, based on various temperature measurements. If cold, it is likely to have to start in so called open loop condition, meaning the mixture will be richer than normal and the idle RPM is higher too. Only when all these conditions are met will it allow fuel and spark to the cilinders. So there is a lot of stuff, sensors and logic that are part of something mundane as starting.

Here is what I would do:
First of all check the battery. Without a good enough battery you are going to get all sort of of totally random faults, including MIL/CEL. Modern cars are very susceptible to having the correct voltage to all components. If your battery is getting old, during starting and especially during a cold start the battery voltage will drop. It might be quite sufficient to turn the engine, but due to the heavy load on the battery the voltage will drop. That can play havoc with the electronics.

I would argue that any mechanic not checking the battery and battery connections before even beginning to trouble shoot simply doesn’t know what he/she is doing.

You need to measure the voltage on the battery terminals during starting. You need to ensure you have the correct measuring instrument as the voltage dips very deep in a very short space of time and then partially recovers as the engine begins to turn over. So you need a pretty high end digital multimeter with high cycle time, or an analogue meter.

Also, do check the charge of the battery, not with a multimeter, but a proper battery capacity measuring instrument. If the voltage drops below say 11-11.5V you might begin to see problems.

If the battery checks out you need to check the battery terminals for corrosion and the ground of at least the engine, the ECU and or PCM. If there is any corrosion on any of these you will never be able to make a correct diagnose, and it might just solve all these problems. And yes that means disconnecting them all, and cleaning them. You can’t tell from a fastened connector or ground whether it has any corrosion.

You will also need to check and clean all the connectors of all the sensors, valves etc of all components in the starting sequence. See below for more information. Anorak fact: When my Jaguar would not start I eventually managed to trace it to a wonky connector. The little clip holding it in place was broken. A 10ct tiewrap solved the problem,. After many years it’s still there holding that connector firmly in place.

Next, you want to make sure the engine actually starts in open loop. In layman terms, the automatic choke needs to come on during the start sequence. Best done with a good OBS scanner, the Audi dealers have dedicated VAG equipment.

I am not sure on these Audi’s but many cars have what is known as an idle or start valve and or also a start injector. These are two pieces that ensure the car starts quickly and the mixture is enriched. Both the operation need to be verified. Neither will trigger a fault code in my experience.

Lastly, the rotation of your engine and thus the signal to the ECU is generated by your Crankshaft and or camshaft sensor. Over time these will deteriorate. No, they tend not to generate error codes. They tend to be inductive type of sensors, which also means they have harder time seeing low revs (as with starting) then at idle or higher RPMs. So they might work fine when the engine is running, but give problems during starting.

These sensors can be easily tested. Some cars have more problems with hpthese sensors than others. It is the reason I always carry a spare in myAlfa Romeo and my Jeep Cherokee.

If the crankshaft/cam shaft sensor is not working properly the RPM signal to the ECU/PCM will be garbled. Which means it thinks the engine isn’t spinning quickly enough and thus it won’t allow fuel to be injected or spark to be generated.

Part of the problem is that these sort of problems tend not to generate error codes.

I think the error codes that were seen are a symptom, but not the root cause.

Good luck, let us know what they find!

Jeroen

[amartya_bhp]

Originally Posted by Jeroen

Given the symptoms you describe, poor or no starting when cold, I doubt very much it is anything like coils or so.

Thanks for these detailed steps and analysis- Audi TT says that they have sorted the issue out and as diagnosed it was the coil, they have swapped with a PDI car and have tested and everything is working fine. They have already ordered the part. I am keeping my fingers crossed an hoping that this will resolve the issue once and for all and I can again start enjoying my car and go out on a trip.

Mod Note: Please quote ONLY the relevant bits of a post. Quoting a full, long post inconveniences our mobile readers.

[Crosscountryman]

Here's my experience of a ghost cold start issue in my VAG car and it's simple incidental solution.

My 2020 Skoda Kodiaq Diesel would not have it's horn and cruise control working, after every cold start (start after a few days), since last winters of Gurgaon. However, both the functions used to come back once the engine was switched off and switched on again.

The Skoda ASS at Gurgaon spent a day upon the car and couldn't find any fault. They made a video of the fault and sent it to Skoda technical team but nothing concrete happened. It wasn't too uncomfortable for me, so I also lived with it.

This October, I got my battery changed precautionarily since it had completed 3 years plus from the date of car's manufacturing and I had few long trips planned with my family. To my surprise, this issue vanished with the new battery and has not reoccurred even on the starts at a gap of 15 days or after a few days in snow.

And while I have updated it to Skoda ASS about this for the benefit of other Kodiaq users but no one really knows why it happened.

[Jeroen]

Originally Posted by amartya_bhp

Thanks for these detailed steps and analysis- Audi TT says that they have sorted the issue out and as diagnosed it was the coil, they have swapped with a PDI car and have tested and everything is working fine. They have already ordered the part. I am keeping my fingers crossed an hoping that this will resolve the issue once and for all and I can again start enjoying my car and go out on a trip.
[/b]

Well, I hope for your sake, it is the coil. But it is a very strange story. A four cilinder engine will start fine if only three cylinders are firing. Also, test a coil is very simple. The VAG diagnostic analyser will indicate which coil is not working or suspect. If you haven’t got a spare one, you just swap the suspected coil with one of the others. If the problem persist and the problem follows the coil to the other cylinder, you can be pretty sure it is that coil.

I am not impressed with their diagnostics at all. All this effort, from compression testing to endoscopic examination of cilinder bore. And then all of a sudden somebody has a bright moment and is convinced the only thing wrong is the coil? Doesn’t make sense to me at all.

Try and get a detailed description of all test that they did, what error codes, they saw, why they believed all these test needed doing?

Again, any mechanic should be able to diagnose a bad coil in minutes. You might have an iffy coil, but I am not convinced that is the root cause of your problem.

Let’s hope I am wrong, good luck!

Jeroen

[amartya_bhp]

Originally Posted by Jeroen

Try and get a detailed description of all test that they did, what error codes, they saw, why they believed all these test needed doing?

Let’s hope I am wrong, good luck!

Jeroen

Thanks for the pointer; I have already told them that I will need all diagnosis reports and test results, initially, they were hesitant and said Audi is not willing, but finally relented and agreed to give hard copies once they vehicle is completely fixed and they hand it over to me after my satisfaction. I have told them to keep the case open for at least 2000 kms to ensure that the problem does not recur.

Hope to get it back next week as I plan to go on a trip to Bandhavgarh and am happy to team up with members who are willing to join in.

[ajs85]

Originally Posted by el lobo 6061

I guess this could be due to E20 Petrol (20% Ethanol).
Also effect of E20 petrol will be more on E10 Petrol engines as compared to using E10 petrol in non-ethanol compatible petrol engines.

High compression petrol engines need proper fuel else they are not gonna function well.

So how to rule out if Ethanol is the issue? Even after getting RON95 fuel, this is the result then what other precautions should be taken? Will the addition of Octane boosters help?

[el lobo 6061]

Originally Posted by ajs85

So how to rule out if Ethanol is the issue? Even after getting RON95 fuel, this is the result then what other precautions should be taken?

IOCL offers XP95 and XP100
HPCL offers Power99 and Power100

You will need to check with both companies whether these high octane petrol fuel contain Ethanol or not.

Then try them out.

XP95 you are already using but still can ask about its ethanol content.

Originally Posted by ajs85

Will the addition of Octane boosters help?

If fuel contains ethanol, adding additives wont help in reducing it.

What does your car manual says about Ethanol content allowed?

[amartya_bhp]

Thanks to all for your suggestions and good wishes - my car is back and running as silk. Even though they did all sorts of tests, the issue was of a faulty spark plug which was not doing its job properly in the cold. They have replaced the part under warranty and now everything looks Good!

Now, am gearing up for Delhi - Gwalior - Bhopal - Sanchi - Bandhavgarh - Jhansi - Delhi later this month - any heads up on the road conditions will be really appreciated. I will be traveling with my wife and son. Thanks again and looking forward to receiving valuable travel information.

[JoshMachine]

Originally Posted by amartya_bhp

Thanks to all for your suggestions and good wishes - my car is back and running as silk. Even though they did all sorts of tests, the issue was of a faulty spark plug which was not doing its job properly in the cold. They have replaced the part under warranty and now everything looks Good!

First they said it was the ignition coil and now they say it is the spark plug to be blamed!
Logically, the coil feeds the voltage to the plug and is all part of the same ignition system but how did they conclusively prove or rather isolate the problem with the plug?

And did they replace just one plug or all of them?

Now, am gearing up for Delhi - Gwalior - Bhopal - Sanchi - Bandhavgarh - Jhansi - Delhi later this month - any heads up on the road conditions will be really appreciated. I will be traveling with my wife and son. Thanks again and looking forward to receiving valuable travel information.

Happy travels with your A4
And please do post some more pictures, I happen to have the exact same car as yours including the terrific Terra Grey metallic color!

[amartya_bhp]

Originally Posted by JoshMachine

First they said it was the ignition coil and now they say it is the spark plug to be blamed!
Logically, the coil feeds the voltage to the plug and is all part of the same ignition system but how did they conclusively prove or rather isolate the problem with the plug?

And did they replace just one plug or all of them?

The error code kept getting shifted between the cylinders randomly and once they changed all the spark plugs, they went away - so that is how they diagnosed, it was showing a P0300 code in the scanning.

Originally Posted by JoshMachine

Happy travels with your A4
And please do post some more pictures, I happen to have the exact same car as yours including the terrific Terra Grey metallic color!

Thanks - I have never been to that area, specially Bandhavgarh, Ranchi and so, hoping that the trip does happen. Otherwise, we have plans to do Delhi - Kolkata - Kharagpur and back. Lets see - either way will post interesting pictures.

[ajs85]

Originally Posted by el lobo 6061

IOCL offers XP95 and XP100
HPCL offers Power99 and Power100

You will need to check with both companies whether these high octane petrol fuel contain Ethanol or not.

Then try them out.

XP95 you are already using but still can ask about its ethanol content.


If fuel contains ethanol, adding additives wont help in reducing it.

What does your car manual says about Ethanol content allowed?

UPDATE: I tried Speed 97 and 100 same results, went to FNG recommended by a friend, culprit found Spark Plugs, one of the spark plugs was not functioning correctly (scoring marks on one of the plug were noticed by him)

Surprisingly no error or check engine light was thrown, when the engine was pushed hard check engine light used to appear used to get reset after the ignition was off. Error, when scanned, was just for the misfire in the random cylinder.

Took things in my hands and sourced genuine Mercedes spark plugs from Germany, and she is back to her older self.

[amartya_bhp]

Originally Posted by ajs85

UPDATE: I tried Speed 97 and 100 same results, went to FNG recommended by a friend, culprit found Spark Plugs, one of the spark plugs was not functioning correctly (scoring marks on one of the plug were noticed by him)

Surprisingly no error or check engine light was thrown, when the engine was pushed hard check engine light used to appear used to get reset after the ignition was off. Error, when scanned, was just for the misfire in the random cylinder.

Took things in my hands and sourced genuine Mercedes spark plugs from Germany, and she is back to her older self.

Good to know that your car is back to her usual self and the issue has been resolved. What is it with these spark plugs of BAM - can they not stand the Indian conditions? Even mine turned out to be a spark plug related issue.

[ajs85]

Originally Posted by amartya_bhp

Good to know that your car is back to her usual self and the issue has been resolved. What is it with these spark plugs of BAM - can they not stand the Indian conditions? Even mine turned out to be a spark plug related issue.

Had the same discussion with the FNG owner and he said Indian conditions are harsh. Normal compression engines somehow cope with them but things get complicated when High compression and Turbo/supercharged come into play. Further adding to this he said the heat rating matching is what is sometimes ignored for the spark plugs and this causes issues. Did your car get any of the spark plug opened? Improperly tightened spark plug will cause issues we are facing. Were you shown the spark plugs? what condition they were in? Asking because what my mechanic told be delayed cold starts are indicative of timing chain/gear issues (first sign even before noise), the cold cranking will increase.