Misfires at cold start with low temperature outside

[STomHacks]

Hi, I know it's a classic subject but I didn't find the right answer and how investigate correctly.

Winter is close and the temperatures are under 0 now. My Audi A4 2.0t has some misfires during some minutes with small idle variations. To let you know, I changed the cam follower, spark plugs, pcv valve few months ago.
I also change one coil pack last month.
If I speed up a bit I don't have misfires it's only during idling and cold start.

I have vcds, do you know how can I check if it's another coil pack issue or an injector (I hope it's not the case) ?

Maybe I can try an injector cleaner product ?

If you want I can provide a video.

Tell me if you want any information

Thank you for your time

[Theiceman]

for me the pcv fixed it .. perhaps you have a small intake leak somewhere ?

[Brillo]

With a scan tool can you isolate the misfire to a particular cylinder? If not, then it could be a lean condition caused by small air leak somewhere as Theiceman stated above. If isolated to a cylinder and you move the coil packs around does the misfire follow the coil pack? How old are your spark plugs? Are you in need of a carbon clean? Fuel injector cleaner won't hurt but don't expect anything here.

[Hugh@EuropaParts]

Misfires on cold starts only are usually fuel injectors.

[STomHacks]

for me the pcv fixed it .. perhaps you have a small intake leak somewhere ?

I changed the pcv valve in June but with a Chinese part. How can I verify if it's a pcv valve issue ?

With a scan tool can you isolate the misfire to a particular cylinder? If not, then it could be a lean condition caused by small air leak somewhere as Theiceman stated above. If isolated to a cylinder and you move the coil packs around does the misfire follow the coil pack? How old are your spark plugs? Are you in need of a carbon clean? Fuel injector cleaner won't hurt but don't expect anything here.

Where on the scan tool I can isolate the misfire ? Of course if it's only on a specific cylinder I can switch a coil pack to see if it's a coil pack issue. The spark plugs are changed in June by Denso IK22 or 24 I don't remember.

Misfires on cold starts only are usually fuel injectors.

Fuck :/ I hope I don't need to change an injector. I did to much work on this car since March.

[Cyrik]

I changed the pcv valve in June but with a Chinese part. How can I verify if it's a pcv valve issue ?



Where on the scan tool I can isolate the misfire ? Of course if it's only on a specific cylinder I can switch a coil pack to see if it's a coil pack issue. The spark plugs are changed in June by Denso IK22 or 24 I don't remember.


Fuck :/ I hope I don't need to change an injector. I did to much work on this car since March.

If you bought a cheap PCV start with that first... they don't last long and getting them at a stealership is still somewhat cheap. Continuous rough idle is usually a PCV issue.

Regarding to the actual misfire... no, it's most likely not the injector itself, but rather carbon buildup on your intake valves. Any sort of intake cleaner WILL NOT remove ALL of the carbon. Simply remove the intake manifold, clean your valves (look up videos on how to do this, there's a few different ways of going about it) then replace just the o-rings on the injectors and the intake manifold gasket and you're good to go. Wouldn't hurt to clean off the injector tips as well.

[STomHacks]

If you bought a cheap PCV start with that first... they don't last long and getting them at a stealership is still somewhat cheap. Continuous rough idle is usually a PCV issue.

Regarding to the actual misfire... no, it's most likely not the injector itself, but rather carbon buildup on your intake valves. Any sort of intake cleaner WILL NOT remove ALL of the carbon. Simply remove the intake manifold, clean your valves (look up videos on how to do this, there's a few different ways of going about it) then replace just the o-rings on the injectors and the intake manifold gasket and you're good to go. Wouldn't hurt to clean off the injector tips as well.

Thanks for your reply, I'll check but maybe I have my old and original pcv valve. I changed mine just in case. I can try first with this.
I'll try to find some videos to clean the valves, I hope it's doable with my beginners skills.

Also, do you know if I can check something on VCDS to see the misfire ?

[EvolutionArmory]

Sudden misfires at cold start around this time of year are usually due to carbon build up on the valves or intake flap motor issues. You’ll probably see a bunch more posts like yours for the next 4 months.

The fact that it only happens at idle and goes away and only when it’s really cold out is almost 100% a sign you need or carbon cleaning.

[Brillo]

Where on the scan tool I can isolate the misfire ? Of course if it's only on a specific cylinder I can switch a coil pack to see if it's a coil pack issue. The spark plugs are changed in June by Denso IK22 or 24 I don't remember.

The error code will tell you which cylinder(s) is misfiring.

I changed the pcv valve in June but with a Chinese part. How can I verify if it's a pcv valve issue ?

Regarding the PCV valve, first carefully pry the top round cap off. The rubber diaphragm and spring are underneath. Make sure the diaphragm is not torn and the area under it is clean. If not, clean with brake cleaner (not carb cleaner) and Q-tips, then reassemble. It's very easy to do. Carefully detach the corrugated tube that runs to the IM at the IM and PVC valve and inspect it for cracks and degraded rubber O-rings. The connection points are easliy broken so take you time disconnecting the tube. (It helps to push the tube on with a little wiggling, then press the lock ring and then pull off also with gentle wiggling.) Make sure the check valve in the PCV valve is working by blowing into the port towards the valve cover. Absolutely no flow should occur, but when sucking on it (don't let the neighbors see this part) it should flow freely towards the IM. Also, carefully inspect for cracks the other corrugated tube that runs from the most rear port of the PCV valve to the oil filter housing.

If you want to run your car with the PCV valve isolated to see if it runs any differently, do the following: Leave the rear tube connected to the PCV valve. Securely place a rubber cap over the IM port. Also, block the port on the PCV valve that attaches to the tube going to the IM (2nd to the rear). In this configuration the IM will not be drawing any blow-by gas directly into the IM. Also, in this configuration, the diaphragm valve will not be activated so all blow-by pressure should flow through the PCV valve directly to the right front pre-turbo breather port. To verify you are not pressurizing your crankcase, run engine at idle RPM with the oil fill cap loosened but still in place. There should be no pressure trying to push the oil fill cap off the VC. Have your mother-in-law in the driver's seat raise the engine RPM (no more than 2000RPM) to see if there is any increase in pressure pushing the cap off the VC. If no pressure increase secure the oil fill cap and take the car for a short drive to see if it runs any differently. If not, you can conclude that the PCV valve is not the source of your problem. Reconnect the tubes to the IM and PCV valve.

[Brillo]

Oh, I almost forgot. At the earliest convenient time get rid of that POS Chinese PCV and get the proper OEM replacement.

[Cyrik]

Oh, I almost forgot. At the earliest convenient time get rid of that POS Chinese PCV and get the proper OEM replacement.

I was waiting for this 🤣

[esandes]

There's a rough cold idle too right?

[Theiceman]

I changed the pcv valve in June but with a Chinese part. How can I verify if it's a pcv valve issue ?



Where on the scan tool I can isolate the misfire ? Of course if it's only on a specific cylinder I can switch a coil pack to see if it's a coil pack issue. The spark plugs are changed in June by Denso IK22 or 24 I don't remember.


Fuck :/ I hope I don't need to change an injector. I did to much work on this car since March.

by putting in an OE one ?

[pezgoon]

If you have VCDS under engine module using monitor blocks or whatever it is called the misfires are group #14 and #15


Sent from my iPhone using Audizine

[pezgoon]

Oh, I almost forgot. At the earliest convenient time get rid of that POS Chinese PCV and get the proper OEM replacement.

Just curious, pcv relationship to misfires?

I’m pretty sure my coils are bad, but I’ve also broken half the connectors, in half, that hold my various pcv tubes on. Do they REALLY matter?

[Brillo]

If you have a torn diaphragm in the PCV valve or a leak in either corrigated tube going to the PCV valve that would allow unmetered air into the induction system which would cause a lean air/fuel charge and consequently a possible misfire.

[STomHacks]

Thank you everybody for all you replies. It's really appreciate to have so much help.
Tomorrow I'll send you a video. But I saw your messages about the tube going to the pcv, I didn't change this tube. I'll check but maybe mine has a leak, I need to check and listen.
I'll also check on VCDS. And finally my coils connectors are broken. I ordered new connectors to fix this correctly.

[blakefife]

mine misfires on cold start in cold weather. But i also just noticed i have a tiny air leak in my passenger intercooler. It will be replaced with a genuine audi one and Ill rescan to see whats going on... I also swapped engines and forgot to change over the newest revised PCV valve i had on the old engine, so Ill do that too and post back with results.

I know this is a very common problem with these 2.0 tfsi engines

[STomHacks]

Hi, I didn't check the intercooler yet and also I didn't try to do a scan with VCDS because I have an issue with my battery, is totally out after only 2 days. But I did a quick video today.

https://streamable.com/1nbl8k

[EvolutionArmory]

Hi, I didn't check the intercooler yet and also I didn't try to do a scan with VCDS because I have an issue with my battery, is totally out after only 2 days. But I did a quick video today.

https://streamable.com/1nbl8k

See post 8.

Get a walnut blast carbon cleaning.

[STomHacks]

See post 8.

Get a walnut blast carbon cleaning.

Do you have a brand to recommand ?

[EvolutionArmory]

It’s not a brand. It’s a service most European mechanics offer.

[STomHacks]

It’s not a brand. It’s a service most European mechanics offer.

Oh, you mean a carbon cleaner for injectors isn't enough ? Like this https://www.amazon.ca/-/fr/gp/product/B06XHTRR79

[EvolutionArmory]

No. Goggle walnut blast carbon clean cold start misfires and watch your whole world open up to hundreds of people who have gone through this already.


Sent from my iPhone using Audizine

[STomHacks]

Hi, I reply about my idling problem at cold on my car. I did a scan with VCDS and I have this :

3 Faults Found:
000768 - Random/Multiple Cylinder Misfire Detected 
               P0300 - 008 -  - Intermittent
             Freeze Frame:
                    Fault Status: 00101000
                    Fault Priority: 0
                    Fault Frequency: 1
                    Reset counter: 255
                    Mileage: 207808 km
                    Time Indication: 0

             Freeze Frame:
                    RPM: 799 /min
                    Load: 42.3 %
                    Speed: 0.0 km/h
                    Temperature: 9.0°C
                    Temperature: 3.0°C
                    Absolute Pres.: 1000.0 mbar
                    Voltage: 13.970 V

000769 - Cylinder 1 
               P0301 - 008 - Misfire Detected - Intermittent
             Freeze Frame:
                    Fault Status: 00101000
                    Fault Priority: 0
                    Fault Frequency: 1
                    Reset counter: 255
                    Mileage: 207808 km
                    Time Indication: 0

             Freeze Frame:
                    RPM: 827 /min
                    Load: 43.9 %
                    Speed: 0.0 km/h
                    Temperature: 9.0°C
                    Temperature: 3.0°C
                    Absolute Pres.: 1000.0 mbar
                    Voltage: 13.843 V

005489 - Left Engine Mount Solenoid Valve (N144) 
               P1571 - 001 - Short to Plus - Intermittent
             Freeze Frame:
                    Fault Status: 00100001
                    Fault Priority: 0
                    Fault Frequency: 25
                    Reset counter: 255
                    Mileage: 207808 km
                    Time Indication: 0

             Freeze Frame:
                    RPM: 1495 /min
                    Load: 25.1 %
                    Speed: 19.0 km/h
                    Temperature: 32.0°C
                    Temperature: 3.0°C
                    Absolute Pres.: 1000.0 mbar
                    Voltage: 14.224 V

Readiness: 0000 0100

Does this confirm the carbon buildup issue ?

Thank you

[esandes]

No. The whole carbon buildup talk is BS.

Those 22 and 24 plugs are too cool. Stock heat is 20. I had horrible misfires with cooler plugs. Go with the NGK 92400. If theres still misfiring I'd get a set of new coilpacks. Not sure about that other code.

[EvolutionArmory]

No. The whole carbon buildup talk is BS.

Those 22 and 24 plugs are too cool. Stock heat is 20. I had horrible misfires with cooler plugs. Go with the NGK 92400. If theres still misfiring I'd get a set of new coilpacks. Not sure about that other code.

So you know more than Audi, BMW, Ford, or EVERY other car maker in the world that makes DI cars and offers this service which is ROUTINE MAINTENANCE? 🤣🤣

It not BS. I’ve performed MANY carbon cleanings and guess what, the problem goes away.

Educate yourself on how the whole cold start system works and why carbon build up on the valves causes it to misfire only when cold.

[EvolutionArmory]

Esandes, his misfire goes away after it’s warmed up. If it was a bad coil pack or plug it would misfire constantly.

Listen. Not every problem can be solved by replacing coils, plugs and PCV valves. I know that’s all you know but when you tell someone a problem that happens on ALL DI cars that don’t have additional injectors is BS, you just look silly.

I don’t know why I care but someone needs to tell you these things.

Esandes, please read this, watch the video and try to understand it so you don’t look like a noob and say carbon build up isn’t real. Of course it is. Learn how direct injection works before you give advice about it.

https://www.google.com/amp/s/blog.fc...%3fhs_amp=true

[esandes]

STomHacks there's obviously a lot of misinformation on internet forums.

I had massive oil consumption and carbon buildup. I used IK20/22/24 plugs. I live in a cold winter climate.

The issues you state started after changing to cooler plugs than required and with cold ambient weather.

Take my advice. Start with the plugs. Forget about the nonsense. Show a picture of the carbon buildup on your cooler plugs. You need stock heat range to clean off the plug to promote sparking.

[STomHacks]

Hi guys, thanks for your replies. For now I can't did the thing to remove the carbon. Idk if it's a carbon buidup issue or a spark plugs issue but the temperature is too cold to work multiple hours on the car without a garage. I purchased a fuel system cleaner for now, I know it's not the best thing but maybe can help.

An about the spark plugs, I have on my car the NGK 2667 BKR7EIX. I have also my old spark plugs BOSCH FR6KPP332S. Do you think it's better with those temperatures ? I can test maybe.

[esandes]

My engine was barely drivable with IK24 plugs.

[STomHacks]

If I check this guide https://www.audizine.com/forum/showt...ent-Guide-v2-0
my plugs are on the right range of temperature. Yours are much colder right ?
But I suppose I need warmer spark plugs no ?

[EvolutionArmory]

You need a 7 heat range. The stock plug is NGK PFR7S8EG so if you’re running a NGK BKR7EIX, you’re running the right heat range for the car already.

Don’t listen to Esandes. He means well but quite frankly, he doesn’t know what he’s talking about most of the time. I won’t be the only one to tell you.

Listen, if you want to rule out a spark plug and spend zero dollars to do it, just move plug 1 to 2 and 2 to 1. Logic tells you that the misfire will now jump to cylinder 2. If it stays on 1, it ain’t plugs.

And the simple fact that the misfire goes away once the car is warmed up tells you it isn’t the plug. Why would the plug stop misfiring once it warms up if it’s bad? It would continue to misfire all the time if it was bad.

[STomHacks]

Ahah, make sense
Yes maybe I can try to change the plugs between cylinder 1 and 2. Do you know how can I indentify the cylinders ?
But I think like you, most probably a carbon buildup problem I guess. But to be sure I'll test with my previous spark plugs maybe.

[EvolutionArmory]

1-2-3-4 from front to back. Swap the first 2 around. Don’t change anything else. Keep the coils in the same place as they were. Just move plugs. And don’t change the plugs. Use the ones that are already in there.

[STomHacks]

Thank you, I'll try this tomorrow

[STomHacks]

Hi, I tried to put the spark plug 1 on the cylinder 2 and the spark plug 2 on the cylinder 1 like we said yesterday. But it's still the same :

000769 - Cylinder 1
P0301 - 008 - Misfire Detected - Intermittent

[esandes]

If I check this guide https://www.audizine.com/forum/showt...ent-Guide-v2-0
my plugs are on the right range of temperature. Yours are much colder right ?
But I suppose I need warmer spark plugs no ?

Those bosch and ngk plugs you quoted are stock heat range-which is what is required to burn off carbon from the electrodes.

[EvolutionArmory]

Hi, I tried to put the spark plug 1 on the cylinder 2 and the spark plug 2 on the cylinder 1 like we said yesterday. But it's still the same :

000769 - Cylinder 1
P0301 - 008 - Misfire Detected - Intermittent

So like I said, never listen to Esandes. I’m sorry Esandes but you do this to yourself. 🤣

You need to have a carbon cleaning done. Fuel additives will not remove the carbon. It can’t since the fuel never touches the valves.

The fact that the car drives normal after it warms up is a dead give away that it just needs a carbon cleaning. The carbon on the valves interfere with clean combustion during the cold start process. Once the car warms up and starts using a different strategy, it runs right.




Sent from my iPhone using Audizine

[STomHacks]

Thank you ElolutiomArmory, I think you have totally right with my car. Unfortunatly I can't do this job by myself during the winter without a garage. I hope the car can continue like this until the spring. Because I suppose this operation by a professional will be really expensive. Do you have an idea of the price for a carbon cleaning by hydrogen by a pro ? Is it efficiency ?