Lasse H

1.6 FSI misfire, intake cam timing adjustment not working?

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As this is relatively important thing to me now, better I do not even try writing German. But feel free to answer in German if preferred. :) 

 

The car is a 1.6 FSI with misfire problem. Misfires do not seem to be caused by spark plugs or coils. Fuel consumption is not excessive. Car is generally quite OK to drive, but misfire is occasionally noticeable. Not bad idle, but there definitely is misfire. Power OK but probably not all there. Engine went through relatively big overhaul in January after a major coolant leak, but it behaved quite similar even before it. It even passed yearly emission test.

 

But, when engine has warmed up, turned off, and restarted after some time (like 15 minutes), misfire is horrible and power is near totally lost.  After few minutes driving it is again relative OK.

 

Diagnostics shop suggests now the issue could be intake camshaft timing adjustment unit. Solenoid is clicking as expected, but they told me disconnecting the solenoids connector did not change engine idles or runs on higher revs. I was told "normally an engine dies when this solenoid is disconnected" (they are *not* VAG specialists however!) They suggest changing the whole timing unit (780€ part + 4 hours work).

 

They are not sure if timing unit is the problem, but are telling me everything else seems to be OK and have no other suggestions. Also, they are complaining how difficult to diagnose this FSI is because of so little sensor readings available. :| 

 

VCDS has never showed any cam timing related errors for this engine, only misfires. Is cam timing really not diagnosed by the ECU?

 

I have also never read about issues with this timing unit from Finnish forums or a2oc.net (for a2-freun.de my language skill is too limited). Is this normal? Should they first try just changing the solenoid (even though it clicks) instead of whole unit?

 

Any other ideas or views how to proceed?

Many thanks already, all thoughts about this will be much appreciated.

bearbeitet von Lasse H

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Your search word in this forum is Zündaussetzer ;)

 

As far as I understood, the most probable cause for FSI misfires after the ignition is the injectors. If you could post a readout of the failure codes, we could possibly help in finding solution pathways. 

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Thanks! :)

 

I could post a typical failure code log later. Anyway, there is only misfire codes, typically 'random misfire' and misfire from two or three different cylinders. I have logged cylinder-specific misfire counters. When idling, some counters increase sometimes quickly. Some misfire is audible from engine running, but not that much. Misfires appear/move in different cylinders. Is detection just not working? Changing a new coil or swapping coils did not affect it.

 

Injectors have not been checked. As far as I know, there is no way to reliably diagnose them without removing them. I guess this should be the next step anyway.

 

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Fault codes in https://a2-freun.de/forum/forums/topic/26646-fsi-zündaussetzer/ look very familiar to me.

 

Could a standing warm engine cause heat build up to injectors, and cause power loss and misfire, after asking more torque from a restarted warm engine...? I did not notice anyone else telling about similar symptom, but maybe I just missed it.

 

 

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Next to the injectors, also the high pressure fuel pump could be under suspect.

 

@Nupi as an "experienced" FSI driver, would you have more tips or suggestions? 

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Mein englisch ist so grottenschlecht , ich kann mir das erst zuhause durlchesen via übersetzer 🙈

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Is your problem really misfire. Before investigate in any expensive parts I would chance the fuel pump, which is build in the tank.  Nupi was searching for a long time about problems with his FSI and in the end this was the root cause.

 

greeting Volker 

 

my my English writing today is not good

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Vielen danke für alle! Das ist sicher besser Englisch als mein Deutsch. :)

 

Yeah, there definitely is misfire, but is it caused by too lean fuel mixture (blocked fuel system?), ignition issue or something else? The fuel pump in tank definitely could be an issue. It is most likely the original one. Maybe misfire cylinder detection just is not so good so misfire errors appear not evenly on all cylinders?

 

I was wishing that serious misfire and power loss after restarting a warm engine would have given some idea about the reason. But there is still too many possible reasons. Maybe it is something ECU does differently, and not directly caused by the mechanical problem.

 

 

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At which cylinder do the errors appear? Does the fault move when the spark plugs and ignition coils are interchanged? If it is, it is easy. Replace spark plugs and ignition coils. If the fault does not migrate, only the ignition cables (rare) or the injection nozzles are suitable. If the fault is in all cylinders, mayby  it is the high-pressure pump, or the pressure-regulating sensor in front of it.  With the pump in the tank the rail pressure collapses.  This has nothing to do with misfires and misfires. Because ignites nothing more.

In german:

Bei welchem Zylinder tauchen die Fehler auf? Wandert der Fehler, wenn die Zündkerzen und Zündspulen quer getauscht werden? Wenn ja, ist es einfach. Zündkerzen und Zündspulen erneuern. Wandert der Fehler nicht, kommen nur die Zündkabel (selten) oder die Einspritzdüsen in Frage. Ist der Fehler bei allen Zylindern, ist es wahrscheinlich die Hochdruckpumpe, bzw. der Druckregelsensor davor. Bei defekter Pumpe im Tank bricht der Raildruck zusammen. Das hat mit Fehlzündungen, Zündaussetzern nichts zu tun, dann zündet nämlich nix mehr.

 

I hope, it helps!:)

  • Danke! 2

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Many thanks for advice again. :)

 

I have never seen misfire error from all cylinders during same fault code reading. Usually they are from 2 or 3 different cylinders, and "random misfire" (can't remember exact wording or code number ). I will check old error logs at home in evening.

 

However, I remember in some point some cylinder stopped giving misfire codes, it "moved" to another. I do not remember if there is one cylinder which has never given any misfires codes. Probably not. However, ECU's misfire diagnosis probably is not 100% robust and codes can be "parasitic"...?  I assume misfires are calculated from crankshaft speed sensor.  But maybe some other inputs or conditions are considered also... I am only guessing.

 

Does a fuel pump (low or high pressure) issue show misfire error codes for every cylinder? Sounds reasonable that it would, but does it work like this in reality?

 

Swapping coils, or changing the worst misfiring to a new coil, did not change anything. I have not swapped spark plugs myself, but thought a Bosch Service diagnosis shop did it. Spark plugs were changed in January during other repairs.

 

bearbeitet von Lasse H

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I had a brief phone call with the diagnosis guy again. He was telling the typical (at least I thought so...) sound during BAD start is actually coming from the intake camshaft timing adjustment unit, and that it should not make that sound. Could it be?  I thought it was from high-pressure fuel pump or hydraulic valve lifter, and completely normal. 

bearbeitet von Lasse H
Improve wording.

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Hello @Lasse H I have now translated the wholete times so I can say: D So I guess the spark plugs and ignition coils are fine. Mostly, a yellow MKL appears in the cockpit. How does your driving profile look? What are you tanking? Are you going short? Are you coming with the A2 still at 200km / h? How many Kilometers? Is the yellow MKL illuminated in the whole time? What would still be the question: -AGR valve? -AGR pipe? (Only with faulty 4th cylinder, mostly) -Einspritzdüsen? (But then the misfires would not be uneven, right?) Alternative evlt. Times an additive reinschütten z.b. Lambda Otto Tank and look for improveme

 

I notice the translator is bullshit 

 

@Nupi

Er hat doch geschrieben das der Fehler unterschiedlich ist, mir käme ja dann eher an etwas elektrischem? Wenn der Fehler über die Zylinder springt und nie wirklich auf einen bleibt, was könnte es dann sein? Motorsteuergerät? Ich denke zwar das es mit die Additiven auch nicht besser wird aber wie @KugelwiderWillen schon mal geschrieben hatte, der Fehler kann so vielsichtig sein. Wenn er keine gelbe MKL hat müsste man evlt. mal das ganze loggen oder?

 

Gruß

Mikey

 

@Lasse H Ich hoffe wir beheben dein Problem :(

 

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Well my English is far from good, but I would say it's o.k.

So I try my best😉!

Well... for me it sounds like the High Pressure fuel pump or maybe the normal pump which influence also the HP Pump.

Maybe the low Pressure pump dont deliver the ~3bar (but this you cant Check via VCDS what I know so far)

You can check the HP Fuel Pump via VCDS for Example the Field 140/3?! It should be the HP Fuel Pressure!

In Idle the HP should be around ~70bar.

With load more...

Maybe you could log this also with the 4 Cylinders  who had the missfire and the "Water/Oil temperature. 

Maybe you also could  do a short "Run " with the FSI and Check if the HP is fluctating under load...

 

But I would say.. if you cant see something in ths logs... change the low pressure Fuel pump,( the solenoid) and Filter in the back and if this doesnt help  the HP Fuel Pump.

 

Or first..., post all your error codes here.😉

 

Hope it helps!

 

Or wait for more answers.😉

 

 

 

bearbeitet von KugelwiderWillen
  • Danke! 2

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Great tips! Thanks everybody! :)

 

The car has 180000km. Driving profile has been mostly city driving (30-70km/h) with some weekly motorway (usually max 100km/h) and highway (80-100km/h) driving. No speeds over 120km/h. Daily driving to work about 10km through city. Generally the engine feels quite good, but has never idled super smooth (during 4 years I've had it) and very slight misfire has been noticeable certain occasionally (for example driving slight downhill with cruise control) .  I've always fueled 98E and twice used injector cleaner (no change). The EGR valve got broke and was changed to a new part a couple years ago. The EGR pipe is original I think. The head was cleaned and rebuilt in January 2017 (checked thoroughly after major coolant leak -- exact reason not known -- sudden high pressure in coolant system which broke from 3 locations). Normal misfire does not light the engine fault indicator in dashboard. But after heated properly and restarted, the light blinks. Sometimes it stays on. The car even passed yearly inspection in early summer, no issues with emissions. But I went there while engine not yet fully heated and had cleared error codes week ago or so.

 

I had chance to get the car back from the diagnostics shop, and already did a bit logging. Fuel pressure readings were not obviously wrong, but I'll take a better look at it still and do more logging.

 

I also logged camshaft timing. First it was OK, but after running engine hot, waiting some minutes and restarting... Intake cam timing really did stop following the setting! Engine fault light blinks, but only misfire codes get logged. Worst misfire and power loss happened exactly during this camshaft issue.

 

 

So definitely there is a problem with camshaft adjustment. I checked the control solenoid N205, but it looked clean. No obvious damage. Electrically it works too (makes clicking sound). Either it malfunctions only after properly hot, or the issue is in the timing adjustment unit (in front of the intake camshaft).  I tried cleaning the N205 but it was essentially clean already. Replace it, or still try better cleaning? The timing adjustment unit is expensive and a lot more work is needed to replace it.

 

 

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