The Misfire Struggle (1.6 FSI - BAD)

xhuli

Member
Hi everyone, I'm Julian I live in France (Strasbourg) and I'm living a nightmare with the famous misfire issue on the A2s.

Here is my story.

I bought an A2 1.6 FSI - 2003 - 98 000 km - Engine code : BAD last month for 1 500€ knowing it had the orange engine light ON (not flashing). Prior to buying it, I dug a little bit and found out the most common repair was replacing a bad ignition coil. So I went ahead and purchased the car, drove it back home. In my way back I drove the most part in the highway and noticed a lack of power when I tried to push it more or when encountering slopes. The engine light, ON at that time, began to flash as soon as I demanded more power from the car. Then I would take off my foot from the throttle pedal and go gently with it. This is how I made the trip back home.

Next day, I put the VCDS on and found the following error codes :

3 Faults Found:
- 16684 - Random/Multiple Cylinder Misfire Detected

P0300 - 35-00 - -
- 16687 - Cylinder 3 Misfire Detected
P0303 - 35-00 - -
- 17912 - Intake Air System: Leak Detected

P1504 - 35-10 - - - Intermittent

So I thought, great I can just buy an Ignition Coil and the issue would be resolved. Prior to buying the part, just to be sure, I inverted the coils between cylinder 3 and 4. The error misfire went to cylinder 4 so I thought yep it's definitely the coil. I went ahead and replaced the coil (BOSCH 0 986 221 023)
on cylinder 3 but then cylinder 4 now would misfire, I was like what the heck is going on.

I then replaced all four Spark Plugs (BOSCH 0 242 240 590) but the same error would remain on cylinder 4. It was at that moment I realized the problem could be much more serious.

So I decided to dig a little deeper an found these FSI engines are prone to carbon build up in the back of the intake valves which could let less air in the cylinder or air wrongly distributed and thus causing a bad combustion. It made sense at the time and everyone on internet seems to agree on this issue.

I was at a crossroad here, either I would do this myself or let a mechanic properly diagnose it. I went for the second option, the mechanic. He did a compression test and told me cylinder 3 was lower than the others but it was acceptable not to worry that much. He also told me that he had a problem adapting/aligning the Intake Throttle Body (OEM 036 133 062 D), I had no clue what it was at that time. The car stayed at his workshop for two weeks with no updates but meanwhile, I don't now why, I was preparing mentally to do all the necessary work myself. I gathered all the necessary infos, workshop manuals, adaptation, tools etc. The mechanic guy didn't do anything more that I already told you by that time and frustrated as I was I took the car back home.

So today, we are two weeks later since I took the car back home and did the following work :

- 1 Ignition Coil replaced - BOSCH 0 986 221 023 - OEM 036 905 715 G
- All 4 Spark Plugs replaced - BOSCH 0 242 240 590 - OEM 101 000 068 AA
- Cleaned and checked :
- Vacuum Control Actuator, OK, leg not broken and retains pressure - OEM 036 129 061 A
- Throttle Valve Flap Potentiometer, seems to be operating ok - OEM 036 907 385 C (G336)
- Air Mass Flow Meter Sensor cleaned - OEM 057 906 461 AX (G70)
- Intake Valve chamber and back of the valves in cylinder head cleaned - OEM 036 109 601 AD
- Injector hole/housing in cylinder head cleaned with a nylon brush
- Injectors cleaned and tested - OEM 036 906 036
- Intake Manifold - Lower part, flaps cleaned and lubed - OEM 036 133 204 K
- Intake Manifold - Upper part cleaned - OEM 036 1298 711 FK
- Vacuum Hose Non-Return Valve, OK - OEM 046 905 291 A
- Exhaust Gas Recirculation (EGR) Valve cleaned - OEM 036 131 503 AD (N18)
- Intake Throttle Body cleaned - OEM 036 133 062 D (J338)
- All connectors cleaned
- Fuses, OK
- Wiring, OK
- Cleaned some earth points, especially the one under the driver's headlight, not oxidized and not broken
- All gaskets replaced :
- AJUSA 13186600 - OEM 03C 129 717 C
- AJUSA 13186700 - OEM 036 129 717 K
- OEM 036 133 073 R
- OEM 036 133 073 Q
- OEM 036 131 550 C
- OEM 036 133 073 F
- Change-Over Flap Valve replaced - BUGIAD BSP25111 or PIERBURG 7.28098.04.0 - OEM 037 906 283 D (N316)
- Vacuum Hoses replaced :
- OEM 036 133 784 J
- OEM 036 133 784 K
- OEM 036 133 773 H
- Intake Manifold Pressure Sensor replaced - METZGER 0906221 - OEM 036 906 051 F (G71)
- Intake Manifold Pressure Brake Booster Sensor replaced - BOSCH 0 261 230 081 - OEM 036 906 051 G
- Vapor Canister Purge Activated Charcoal Filter System Valve replaced - BOSCH 0 280 142 347 - OEM 058 133 517 B (N80)
- Hall Sensor replaced - HELLA 6PU 009 121-451 - OEM 036 906 455 A (G40)
- Injector replaced - BOSCH 0 261 500 005 - OEM 036 906 036
- 4 Injector seals kit replaced - BOSCH F 00V H35 001 - OEM 036 198 149
- 4 Insert Injector seals/o'ring replaced - TOPRAN 111 414 - OEM 035 906 149 A
- Fuel Pressure Sensor replaced - RIDEX 3942S0003 - OEM 06D 906 051 A (G247)
- Fuel Pressure Metering Valve replaced - BOSCH 0 280 160 557 - OEM 037 133 035 C (N290)
- Fuel Filter replaced - BOSCH 0 450 905 316 - OEM 6X0 201 511 B
- Cap Fuel Tank replaced - FEBI-BILSTEIN 27288 - OEM 1J0 201 550 AS
- Air Filter replaced - BOSCH 1 457 433 538 - OEM 8Z0 129 620
- Oil Filter replaced - BOSCH 0 451 103 318 - OEM 030 115 561 AB
- Dust and Pollen Filter replaced - BOSCH 1 987 432 357 - OEM 6Q0 819 653
- Coolant Temperature Sensor replaced - STARK SKCTS-0850018 - OEM 06A 919 501 A (G83 - 2 Pin - Gray - This one communicates with the ECU)
- Drained the fuel as I was not sure what the car had in it before and put some AGIP SP98 Tech+.

When reassembling I plugged in VCDS went to Engine Module, Cleared Codes, Basic Settings and did the following adaptations in this order :

- MVB* 060 - Throttle Body Adaptation, ADP RUN then OK
- MVB* 142 - Intake Manifold Flaps Adaptation, ADP RUN then OK (put a pin on the Vacuum Control Actuator when reassembling)
- MVB* 074 - Exhaust Gas Recirculation Adaptation, ADP RUN then OK

*Measured Value Block

After replacing all those parts and following these minute procedures I still have a misfire problem at cold and at warm temperature. The engine idle is not great, it's like before I did all the replacements, the car shakes. I still have the same error codes but on cylinder 4 now.

3 Faults Found:
- 16684 - Random/Multiple Cylinder Misfire Detected
P0300 - 35-00 - -
- 16688 - Cylinder 4 Misfire Detected ---------------- Engine Light flashing when I really push the car at high RPMs
P0304 - 35-00 - -
- 17912 - Intake Air System: Leak Detected ----------- This error appears when I really push the car at high RPMs

P1504 - 35-10 - - - Intermittent

I was so mad at this point. Checked again with VCDS cylinder misfire count MVB 016 and indeed cylinder 4 was misfiring a lot. I decided then to take the Coil cyl. 4 and put it to the other cylinders and the error followed the bad coil. My guess now is that I believe that I had more than one bad coil to begin with. I should have just bought a pack of 4 Ignition Coils (I was in the cheap side in the beginning). So, as I already replaced one coil my next step is buying three others and maybe a pack of 4 Iridium Spark Plugs DENSO 4702 IK20TT.

It should come in 2 or 3 days max and I will let you know if the issue will be resolved.

What I might be doing in the next days, will be a proper compression test and run a fuel trim short/long diagnostic. Might also check the EGR metal hose/tube if there isn't any leak there.

What do you guys think of what might resolve my issue? Any help is welcomed, I'm on the brink of giving up here.
 

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A2 Louis

Banned
Welcome to the forum :)

replace the high pressure fuel pump as they tend to go bad around the 100k mark

With my FSI I spent around £550 to stop my FSI misfiring I changed all the fuel pumps and that solved the misfire

All old fuel pumps were found to be ok but the high pressure fuel pump had gone faulty

Im 90% sure this is your problem as this is what happened to me and same codes showing:)

New high pressure fuel pumps are £500 I believe but you can get one of here for £50/100 but make sure it’s of a low mileage FSI

Have you upgraded to the market place yet for £2 ?

It definitely pays for itself in the long run

You save hundreds on parts:)

@A2Steve have you got a high pressure fuel pump ?
 

xhuli

Member
Hi!

Thank you for your fast response. I did as you said, paid the £2 for the upgrade and made a donation by the way as I gathered a lot of information in here. My way to say thanks.

So when you talk about the high pressure fuel pump, your talking about this part BOSCH 0 261 520 010 - OEM 036 127 025 J, right?

And you say you had almost the exact symptoms as I'm having?
 
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Robin_Cox

Member
Are you using Super+ fuel? The FSi requires the best possible grade of petrol that you can buy (98-99 octane minimum from a premium grade ie Shell) ; using standard supermarket 95-grade petrol is not advised.

Edit - I notice now reading the small detail you are using Agip 98+, sorry.
 

xhuli

Member
Are you using Super+ fuel? The FSi requires the best possible grade of petrol that you can buy (98-99 octane minimum from a premium grade ie Shell) ; using standard supermarket 95-grade petrol is not advised.

Edit - I notice now reading the small detail you are using Agip 98+, sorry.
Hi!
Yeah I put some good quality 98 fuel but I don’t know the car’s fuel history. If the previous owner ran his car on 95, could it be possible that some parts may be damaged? Like the tank fuel pump, fuel filter, control valve, high pressure fuel pump, high pressure regulating valve, injectors, spark plugs or even the piston rings.
The workshop manual states that 95 fuel can be used but will result in lower performances.
 

PlasticMac

Member
Hi,
Take on step at a time, assess the outcome, then step two will probably be obvious. My FSI had two new Bosch coil packs, and two original VAG coil packs when I bought it. Although I had no warnings or error codes, there was little torque at low revs, and acceleration was hesitant. Changing the two original coil packs to Bosch, and fitting new plugs improved things. It's perfect now, quick get away every time. Let us know when you've fitted your new coil packs. Finger crossed for you. Mac.
 

A2 Louis

Banned
Hi!
Yeah I put some good quality 98 fuel but I don’t know the car’s fuel history. If the previous owner ran his car on 95, could it be possible that some parts may be damaged? Like the tank fuel pump, fuel filter, control valve, high pressure fuel pump, high pressure regulating valve, injectors, spark plugs or even the piston rings.
The workshop manual states that 95 fuel can be used but will result in lower performances.
Hi yes I was having the same issues as you and if I rev the engine to 4000 rpm the EML would start flashing

After changing the high pressure fuel pump shown below the misfire went away and the car ran a dream:)

AB42C959-052D-479D-A48E-BD888550F72A.jpeg
 

xhuli

Member
Hi,
Take on step at a time, assess the outcome, then step two will probably be obvious. My FSI had two new Bosch coil packs, and two original VAG coil packs when I bought it. Although I had no warnings or error codes, there was little torque at low revs, and acceleration was hesitant. Changing the two original coil packs to Bosch, and fitting new plugs improved things. It's perfect now, quick get away every time. Let us know when you've fitted your new coil packs. Finger crossed for you. Mac.
I just ordered via Amazon :

- 3 new Coils (https://www.amazon.fr/gp/product/B004YZS39W/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1)
- 4 Iridium Spark Plugs (https://www.amazon.fr/gp/product/B00TPU8R2Y/ref=ppx_yo_dt_b_asin_title_o00_s01?ie=UTF8&psc=1). I hope these are compatible

The parts should arrive on Tuesday so let's pray it will resolve the issue. But something tells me that this isn't the end (yet). As @A2 Louis said the High Pressure Fuel Pump might be faulty on mine and I'll maybe end up replacing that part as well. One step at a time :)
 

Jellybean

Admin Team
I just ordered via Amazon :

- 3 new Coils (https://www.amazon.fr/gp/product/B004YZS39W/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1)
- 4 Iridium Spark Plugs (https://www.amazon.fr/gp/product/B00TPU8R2Y/ref=ppx_yo_dt_b_asin_title_o00_s01?ie=UTF8&psc=1). I hope these are compatible

The parts should arrive on Tuesday so let's pray it will resolve the issue. But something tells me that this isn't the end (yet). As @A2 Louis said the High Pressure Fuel Pump might be faulty on mine and I'll maybe end up replacing that part as well. One step at a time :)
As advised by Louis, contact @A2Steve who may well have a good Fuel Pump available at a reasonable price.
He has just broken an FSI.

Sent from my SM-N960F using Tapatalk
 

A2Steve

A2OC Donor
As advised by Louis, contact @A2Steve who may well have a good Fuel Pump available at a reasonable price.
He has just broken an FSI.

Sent from my SM-N960F using Tapatalk
Already gone sorry. They tend to sell within a couple of days and usually to German members. I think the FSI now has a far greater following there.
 

xhuli

Member
Ok guys, a week has passed and I'm back to give you some news. A lot has happened so I'll be dividing this by day and by post so bear with me. I'll try to summarize as best as I can and give you all the details. So here it goes.

MONDAY (next day following my first post)

The morning I went to work with the car tryin' to put some miles on it telling myself that the new fuel I added might add a difference in the misfiring issue. No difference so far.

In the meantime, my 3 new Ignition Coils (BOSCH 0 986 221 023 - OEM 036 905 715 G) had arrived. Late afternoon I went ahead and installed them. After installing them, the engine was already starting to feel much better. And guess what no more engine light. Finally, I'm seeing the end of the tunnel I said to myself.

I still noticed some misfire though in Cylinder 3 (the one with less compression). I hooked up the VCDS and it was misfiring like 20 counts per cycle*. Before that it was like 200 counts per cycle, so a huge difference there. Next step was the Iridium Spark Plugs which came the next day.

*cycle = 1 or 2 minutes period and then it resets the count
 

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xhuli

Member
TUESDAY

While driving to work I noticed my coolant temperature gauge in the instrument cluster was acting weirdly, going down as soon as it reached the 90°C mark and going up again randomly. I had already purchased that part just in case (STARK SKCTS-0850019 - OEM 059 919 501 A) (G62 - 4 Pin - Green - Ths one communicates with the Instrument Cluster). My new Iridium Spark Plugs (DENSO 4702 IK20TT) also came in that day. So I decided to replace them later that afternoon. I began with the most difficult part, the Coolant Temperature Sensor (CTS) (G62). It was a huge pain in the ass as I had to unbolt the two 12 point screws from the EGR Hose, it was in the way and blocking the access. I was hoping to inspect that hose for any leak but I found out that you can only remove it by removing the High Pressure Fuel Pump first so I let it go. I was only able to slide it back and forth and accessed the CTS. When removing it, I lost all of my coolant but it was ok as I had some G12 coolant layin' around. Ok so CTS replaced with new o'ring, filled the car with new coolant, waited for the thermostat to open (at 105° I believe), adjusted the level and the coolant temperature stayed at 90°C. The problem was resolved. But In the process I broke a junction coolant piece (OEM 1K0121087B). I did a quick fix thinking that it would hold the time the new part would arrive from Audi.

I then replaced the BOSCH Spark Plugs with the DENSO ones and my God the engine was running so smooth and no more misfire issue (monitored it closely with VCDS over a 30min period while driving). I was so happy at that point, you cannot imagine.

I bought this car for my wife for practical reasons and for her birthday at the same time. I was so happy to see her reaction when I announced to her the car was finally repaired. Priceless.
 

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xhuli

Member
WEDNESDAY

That day my wife took the car for a ride, enjoying herself you know. A few hours later I got a call from her saying she got a big red alert light in the instrument cluster. I told her to get back right away as I guessed what the problem might be. And I was right, it was that fix I did in the junction coolant part which didn't hold. I went right away to a tool and equipment shop and bought a plastic T piece for gardening purpose. I was afraid that it might melt at those temperatures but it did the job (at least it still holds at this day, Sunday).

Did the whole coolant procedure and the car was running great again. Late afternoon I decided to polish the front headlights as they were on the yelloish side of things. The result turned out to be great.

But the next day is the day where things get complicated again.
 

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xhuli

Member
THURSDAY

My wife takes the car doing some shopping and when she came back to the car, she noticed a huge puddle underneath the car and it smelled gasoline. She decided to start the car but the engine was like coughing and then I got the call and told me the car leaked gasoline. In my head I started to worry, wondering what was that about. She left the car there and I went there to see. I started the car and went underneath only to see in my disappointment a huge gasoline leak. Nothing was leaking from above the engine, followed the fuel line till the bottom/lower intake manifold but everything was ok. I started to worry thinking it might be a leak from the injectors. Checked also the return hose from the bottom/lower intake manifold, nothing there. Huge disappointment at that moment because I knew in order to investigate further I had to remove the intake manifold again and it's not a 10 min job.

I left the car there over night and came back tomorrow.
 

xhuli

Member
FRIDAY

I towed the car with my good old loyal A6 C5 1.9TDI and drove it back home. I started the whole disassembly procedure and find out a snapped o'ring on the brass injector insert cylinder 3. How in the world could that happen as I had drove the car around 300 km since Sunday and believe me I did put the car in some stress test and everything was running fine at that point. How can it snap this easily and why? Could I have mounted the lower manifold wrongly? But then the leak would have started right away, no? I did everything as specified in the workshop manual, lubed those o'rings with clean engine oil, put the o'ring on the brass inserts and then the brass inserts to the lower manifold insert housing and the whole thing on the engine block carefully placing the lower manifold on top of the injector and pressing them in place and finally screwed it down as specified in the manual.

I had a spare o'ring from 1 injector seal kit (BOSCH F 00V H35 001 - OEM 036 198 149) and replaced the damaged one. By eye they seem to be the same as for the brass insert o'rings.

When assembling I broke another junction coolant piece (OEM 1J0 121 087 D). So brittle those parts. But it wasn't the only piece I broke. When re-installing everything, I found out I had a gasoline leak from the return pipe from the lower intake manifold (OEM 036 133 713 F). I was so fed up at this point. This car the whole time has been like repairing one thing and breaking an other. I decided to leave it for that night.
 

xhuli

Member
SATURDAY

Knowing that I would never receive the coolant junction part in time to finish the car for the weekend I went to cross-reference that part and found out it was used in many cars such as Golf MKIV 1.9TDIs (OEM 1J0 121 087 B) (a common car found everywhere and abundant in parts where I live). So I bought it from someone in a used engine and bought also some furniture like fuel line/pipes, new clamps (hate those stock clamps, too tight and damage the pipe too easily), new G12 coolant and a proper clamp pliers.

I took the rest of the day off as I needed a break here. I left it for Sunday (today).
 

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xhuli

Member
SUNDAY

I took back the operations early this the morning as I wanted to have the rest of the day to proper testing the car but nothing went as I was hoping for.

First thing I noticed, the used part I bought from the used MKIV engine was not the right part, it was too big for the coolant pipe/hose to fit. I thought great it already begins badly. I thought the letter in the end of the part number was like a new production run but I was wrong. In some cases it applies I think but not on this one unfortunately. In the end I ended up modifying the original broken part with a Dremel and it did the job quite well. I will order the proper part shortly.

In order to replace the return fuel pipe from the lower intake manifold, this time I just proceeded to take out all the screws from the upper intake manifold and putting it aside to the right not removing it completely, just creating enough space to take off that pipe as it's kind of hidden/blocked by the upper intake manifold.

Mission accomplished. Everything was back in order again, put the new coolant and let the engine rise in temperature. Everything was running fine and I decided to take the car off the jack stands in order to do a quick test drive. 5 minutes later I began to smell gasoline inside the car and I was completely hopeless, I was like no no not again please give my satisfaction of working on a car for so long and this intensely. I was physically and mentally tired so much at this point that I reached almost the critical point of giving up. It was huge huge disappointment. After inspecting visually the car from underneath, I found out it was another leak. What the hell? What is going on?

I took it upon myself and give it another try to see what happened this time. So I repeated the disassembly procedure again, I gave up counting how many times I have done this, only to found out yet another snapped o'ring on the brass injector insert, only this time it happened on cylinder 1.

I mean come on what's going on? What am I doing wrong here? Are these TOPRAN 111 414 o'rings the issue? They were cheap I recognize (0.53€) but lasting 4/5 days that's not normal. Factory defect?

I left the car disassembled and tomorrow I'll go directly to the Audi dealership to order new Injector Brass Insert (OEM 036 133 235) and new Injector Brass Insert O'Rings (OEM 035 906 149 A). I hope they'll have it stock.

Right now this car has made me paranoid from any sources of noises, smells and other things. It's like I'm driving a car made from glass. And even if I replace these o'rings I will still live in fear of the idea that the car might go haywire at any moment, unexpectedly. This is how I'm feeling right now, I'm not optimist anymore.

So what are your thoughts on this guys? Need some insights, some Guru expert on this.
 

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xhuli

Member
I admire your determination, don't give up now, sounds like you are almost there.
Thanks man! Appreciate it!

It is so frustrating to know that I’m almost there and that those small tiny parts (o’rings) can cause such a hassle.

Anyway I just got back from the Audi dealership and bought 4 new OEM Insert O’Rings. The part number has changed since 2016 and they are gray now (OEM WHT 005 422 B). If those snap too then I’m definetely doing something wrong here.

I have to go to work soon so I’ll leave it maybe for tonight or tomorrow.

I’ll keep you updated regardless the outcome.
 

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