[1.6 fsi] - Misfire or something else

Its a working document example but I haven't put a watermark on the document that says that.
Sorry for the confusion.
I'm asking @Evripidis if they have the time to point out the error I have made but I believe it to be SSP 253 is for the polo 1.4FSI
 
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PlasticMac said:
What is the purpose of:
"Take a test drive and identify speed/load of the hesitation
Remove N80 electrical connector and take a test drive and copy previous speed and load"
Is it to check the N80, (tank vent storage purge valve), is, or isn't opening?
I think you'd need to to run a log to identify the load/speed, and misfire count, pause the log, unplug the N80, restart the log, and repeat.
Mac
Click to expand...
By unplugging the N80, it will not open, so no purge. If the hesitation goes away, it would point to a leak in the tank vent, between the N80 and the tank, including the charcoal canister, so a good idea, no log required.
That was what another member had, with a leaky petrol cap, again on an FSI.
Mac.
 
I think I copied there idea to the document.
I cannot take-credit for it.
I'm using the working document to build a library if ideas. I only created it a couple of days ago, very much work in progress
 
Rolling tests will have to wait. The tires feel like playing Russian roulette.

But I wouldn't be surprised if an injector has gone. 176k miles on them with most of them running on 95 octane most probably.

Gave them an ultrasonic bath when I had them out but still.
 
Hi all,

I am back with some more information.

I drove a fair bit of distance today, comparatively to the usual trips round the block. Maybe 44 km.

I have some coolant loss at the oil cooler pipes but I think this is minimal.

The misfires get a lot worse when warmed up and then idling. It feels like the choke is pulled on a carburated motor.

On the other hand I noticed that the VVT valve is buzzing like mad when the key is off the ignition. I measured the voltages on DC and I am getting 12v on one pine and 2.5v on the other one. There is some AC in there but could not measure it precicely.

Is this normal?

Evros
 
Evripidis said:
Hi all,

I am back with some more information.

I drove a fair bit of distance today, comparatively to the usual trips round the block. Maybe 44 km.

I have some coolant loss at the oil cooler pipes but I think this is minimal.

The misfires get a lot worse when warmed up and then idling. It feels like the choke is pulled on a carburated motor.

On the other hand I noticed that the VVT valve is buzzing like mad when the key is off the ignition. I measured the voltages on DC and I am getting 12v on one pine and 2.5v on the other one. There is some AC in there but could not measure it precicely.

Is this normal?

Evros
Click to expand...
It's DC, but PWM.
Don't think it should buzz though.
VCDS to at the Cam Sensor, see what the adjustment mech is doing.
Group 091.
You may well see cam sensor fault on an ECU scan, do you have an EML?
Mac.
 
Too tired to break out the picoscope. Or vcds for that matter. I have to get a new laptop for better or for worse.

No EML whatsoever. Feels strong enough but it is evident that it is lacking somewhere. The way misfires are recorded I need a battery-powered laptop to catch them at all cylinders. When idleing it will only detect on #4.

Swapped out the old solenoid for the old one. Much better. There is still a faint hum but not a buzzing noise. Goes away after a while in both cases.
 
Evripidis said:
Too tired to break out the picoscope. Or vcds for that matter. I have to get a new laptop for better or for worse.

No EML whatsoever. Feels strong enough but it is evident that it is lacking somewhere. The way misfires are recorded I need a battery-powered laptop to catch them at all cylinders. When idleing it will only detect on #4.

Swapped out the old solenoid for the old one. Much better. There is still a faint hum but not a buzzing noise. Goes away after a while in both cases.
Click to expand...
The solenoid, and the oil pressure driven vane pump can suffer from long periods of inactivity, (bit like us). So, a bit of light excercise might help get them moving freely. No EML, so could be just a lazy valve, 🤞
Mac.
 
There is definitely some action going on for some time after the ignition is turned off, unless the ECU is toast.

The buzzing could be because of what you say, a bit tired, hopefully not retired yet!
 
The symptom could suggest a burnt valve guide. After searching for hours on and on on VAG forums.

Cylidner 4 sitting next to the EGR contributes.
 
OK, riddle me this...

I unplugged the EGR, 30 miles round trip, mox of thrashing it and babying it. Missfire definitely still there....NO EML!
 
Decided to come on this morning...on second startup. Haven't plugged it in yet.

All vag forums say burnt valve. I think this one two has had a couple of threads.

Does bot always show on compression test.
 
Hi to all,

I am chasing the long-term and short-term fuel trim values in vcds for the fsi.

I cannot make any sense! Where are they and in what for do they appear.

I have searched the forum but still could not make it out. Very few threads.

From what @PlasticMac says in his file these values should be in the groups 33 through 37.

EDIT: OK, I think I made sense of it. I'll come back with some more questions or results.

Evros
 
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I don't think the average fuel trims are accessible, or even if they are stored.
Recent posts in @AndyBa Azure Blue FSI thread might be helpful. (#82 onwards).
Groups 003, 007, and 031, show what's going on quite well.
Mac.
 
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@PlasticMac Hi Mac, so groups 32 and 33 show nothing for us?

I had some time this afternoon to sit down and do some more reading as you suggested. The car has been returning 47mpg daily for 40km rountrips.

I was getting nearer to a conclusion after inspecting the following:

032 Idle = -2.3%
032 Partial = 10.2%

033 STFT = +/- 2-4%

These figures along with the constant misfire on #4 cylinder could suggest:

1. On idle it is running too rich.
2. On throttle it is running too lean.

So if an injector is not performing correctly across its duty cycle range I would get such indicators, i.e., too much fuel on idle and too little under load.

I will get to @AndyBa's thread in a minute.

Evros
 
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The Lambda should be around 1 for startup, Once running, it'll increase, as the engine warms up.
Once it's hot, mine runs a Lambda of close to 2, very lean, because of the inlet flappery, and higher running temperature, it's all part of the FSI magic.
There's a spreadsheet log on the @AndyBa thread.
Mac.
 
Still very vague on what the rest of the groups say or mean. Every youtube video and forum post on VAGs only mentions 32 and 33 to the point that is is standard to refer to these readings as long term idle/partial and short term fuel trims.
 
A very interesting read over here:

forums.audirevolution.net

Mother says clean your FSI fuel injectors

Justin suggested starting a thread about FSI fuel injectors and the potential problems caused by carbon buildup on/in the injectors. There’s not much information specific to the RS4 available on the subject so this is a good place to start. I’ll start with my recent symptoms and the diagnosis...
forums.audirevolution.net forums.audirevolution.net

including the comment section.

Evros
 
Evripidis said:
Still very vague on what the rest of the groups say or mean. Every youtube video and forum post on VAGs only mentions 32 and 33 to the point that is is standard to refer to these readings as long term idle/partial and short term fuel trims.
Click to expand...

I'm not convinced that generic YouTube content is much help when trying to understand the FSI/BAD engine.

The only definition of FSI/BAD ECU Groups, that I know of, is based on the label file.
Here's what is shows for Groups 31, 32, & 33:

Group 031, Lambda Control (Lambda Sensor Voltage)
Block 1,Sensor 1,voltage (actual)
Block 2,Sensor 1,voltage (setpoint)

Group 032, Lambda Control (Learning Values)
Block 1, Sensor 1,idle (sum),Value range: -25.0...+25.0 %
Block 2, Sensor 1 partial,load (product),Value range: -25.0...+25.0 %

Group 033, Lambda Control
Block 1, Sensor 1,,Value range: -25.0...+25.0 %
Block 2, Sensor 1,voltage

I understand Group 031. Lambda Voltages, Actual and Setpoint.
I don't understand Groups 032 & 033. When I can, I'll log them, and that'll, probably, give me a clue.

If we can find data that would help diagnose injector problems, that would be a very useful.

Mac.
 
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