Alfa Romeo MITO P1062

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Alfa Romeo MITO P1062

Postby RYM6746 » Sat Aug 19, 2017 12:45 pm

Hi All
I have a Alfa Romeo MITO 2013 Chassis ZAR9550000X010445 fault code P1062 CYL 2 UNIAIR actuation solenoid sticking. In layman's terms I think this is a variable valve lift solenoid. It misfires only when engine is cold (possibly due to thicker oil) and then runs perfectly the fault code only gets stored when cold. when engine is hot and fault is cleared the fault code does not return until the next cold start. The engine oil has had a flush and been changed with correct oil and filter but still fault persists only on cylinder 2. I have scoped the solenoid current of a good and suspect bad along with the MAP sensor. I have never seen this system before, so I am hoping some one can help confirm the solenoid failure. There are definitely irregularities in the waveform starting with the peak current at turn on being a slightly different shape to the other solenoid (channel B poss bad Channel C poss good) and the pulses in the MAP signal seem to match every other turn on event with suspect solenoid not sure why every other? The waveform is taken when the engine is cold and misfiring. Coil and plug have been swapped around but fault code P1062 is still the only code returning. Any help or tests that any one can think of will be much appreciated. There are 4 solenoids, 1 for each cylinder and I would need to purchase a special tool to remove the valve lift assembly and solenoid. Sorry you may have to filter MAP sensor as I have saved file without filter. Thanks
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Re: Alfa Romeo MITO P1062

Postby STC » Sat Aug 19, 2017 5:08 pm

Rym

Measuring Voltage is not the way forward here, get an amp clamp around the 4 orange wires somewhere in the loom and another clamp on coil 2. No real need for MAP as RPM can be calculated from the coil pulse.

Get that recorded as it fails and you should have your answer.
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Re: Alfa Romeo MITO P1062

Postby RYM6746 » Sat Aug 19, 2017 5:37 pm

I havn't measured voltage on the solenoids only the map sensor. I just havnt told the scope I have amps clamps on. No big deal just do the maths your self, can't see how it would help in the diagnosis? I have scoped the map to see what effect the solenoid has on the valve opening pulses (not sure if that was correct or not but seemed like the most likely place to be able to see the physical effect of the solenoid). How is a coil current ramp going to help me diagnos a variable valve lift solenoid?

You can clearly see the misfire in the map sensor zoomed in at idle when engine is started on capture 1. The misfire isn't the problem per say it's proving beyond a reasonable doubt that the fault code is correct and it is the solenoid causing the problem. I have never seen this engine/system or fault code before and there is a fair amount of work and a special tool involved so I need more than a fault code and a slightly irregular current waveform to condem it.

I have noticed that every 8th pressure waveform has a "valley" missing it is just a large upwards slope? tends to suggest that particular cylinder is not pulling the same amount of vacuum as the others on every other 4 stroke cycle? At idle with a filter of about 100Hz
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Re: Alfa Romeo MITO P1062

Postby STC » Sat Aug 19, 2017 8:04 pm

I have amps clamps on. No big deal just do the maths your self,

Then I would have to guess what amp clamp, what setting .... Not worth the bother. I saw the voltage scales on A & B then didnt look any further. Not mind readers

can't see how it would help in the diagnosis?

other than accuracy and correct description it wont.

there is a fair amount of work and a special tool involved so I need more than a fault code and a slightly irregular current waveform to condem it.

I agree, plus once you start to pull it apart any window of diagnosic opportunity is gone.It is quite clear through the trace that the Solenoid on Channel C is moving freely, it has sharper lines compared to the one in Cylinder 2. That can be seen to struggling to move as elegantly as the other.

Once again an amp clamp around the 4 orange wires might show you 3 behaving one way and another differently.

Then you can decide if you have a faulty solenoid or a mechanical issue hindering the smooth & free movement of it.

I have noticed that every 8th pressure waveform has a "valley" missing it is just a large upwards slope? tends to suggest that particular cylinder is not pulling the same amount of vacuum as the others


That raises more questions than it answers :?:

Might be an idea to pull the MAP off, long shot in the dark but could the ECU be looking at that irregular MAP and decided that a defective / sticking Solenoid is causing it ??

Dynamic Cylinder pressure measurements ?
Last edited by STC on Sat Aug 19, 2017 9:43 pm, edited 1 time in total.
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Re: Alfa Romeo MITO P1062

Postby RYM6746 » Sat Aug 19, 2017 9:30 pm

Yes sorry I forgot to mention that I had forgotten to set the scale to amps. But I can't put one amps clamp around the orange wire as all solenoids run on seperate circuits from the ecu. I only have to amps clamps so I have to compare the poss bad to the other 3 which were all identical.
That's the trouble with trying to remember every detail of the diagnosis and cramming it all into the first post.

I am glad I have a second opinion on the current waveform that matches mine. Thanks for your time and help and any more tests or advice is welcome as always. I will be informing customer of my findings on Monday and will see how far he would like to go. N197 is the actuators in question so again there is no 1 amps clamp connection easily they are too far apart and it would involve extending the wires (too much work involved much easier to use 2 seperate clamps)
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Re: Alfa Romeo MITO P1062

Postby STC » Sat Aug 19, 2017 9:51 pm

. But I can't put one amps clamp around the orange wire as all solenoids run on seperate circuits

I know, they may need a capacitor each to keep up with the inrush current demand to dance, but all 4 wires will be together in the loom somewhere.

The loom of wires is taped up to keep it together and out of harms way - Not to keep the Diagnostician out ?? :)

Please read my post again as I edited and added to it as you were writng yours. There is confusion due to that.
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Re: Alfa Romeo MITO P1062

Postby RYM6746 » Sun Aug 20, 2017 11:38 am

I will try and do an in cylinder pressure waveform and see if it will help pin point this solenoid.
Is anybody familiar with this system and knows of a test that can help me to accurately eliminate or condem this system?
To be honest I am amazed that the ECU is picking up a so called sticking solenoid. I find it hard to believe that the ECU is monitoring the MAP or solenoid current in that much detail. There doesn't appear to be a feedback sensor? A misfire code I could understand but that would just enlarge the list of possibilities. So how is it accurately producing this code every time?
I have found this information so is it plausible that if I manually operate the solenoid (if possible due to capacitors being involved) whilst monitoring in cylinder pressure it shouldn't open the inlet valve? I may be scratching around here but there has to be away to prove this. I understand this is not a common system but if we all put our knowledge together and develop a test we will all benefit from it for years to come

I don't think monitoring all the current waveforms through 1 amps clamp will help as they are fired and held on over the top of each other (if that makes sense ) I think it will probably confuse matters as you won't see 4 individual events
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Re: Alfa Romeo MITO P1062

Postby STC » Sun Aug 20, 2017 2:57 pm

I will try and do an in cylinder pressure waveform and see if it will help pin point this solenoid.

Worth doing but I doubt if it will do much more than confirm cylinder condition. I imagine it would see the misfire and possibly shut down the solenoid too - I don't know for sure.

To be honest I am amazed that the ECU is picking up a so called sticking solenoid. I find it hard to believe that the ECU is monitoring the MAP or solenoid current in that much detail.

I'm sure it is not the first time an ECU strategy has amazed you ?

I don't think monitoring all the current waveforms through 1 amps clamp will help as they are fired and held on over the top of each other (if that makes sense ) I think it will probably confuse matters as you won't see 4 individual events

Good Point, makes sense, But we would see the 4 current peaks, that is all we are interested in with this one. Or all with 2 clamps - more separation.

Multi Air 1.jpg


I would like to see the same capture above but with voltage to each solenoid too - without the MAP. That should show what it is "asked" to do and what it is "doing" - A hike in PWM Command is what I would be asking Santa for! :)
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Re: Alfa Romeo MITO P1062

Postby RYM6746 » Sun Aug 20, 2017 3:16 pm

I have noticed that there is definitely a relationship between the peak current irregularities and the irregularities in the pulses of pressure. It would seem that after starting with the misfire present the missing dip has a "tick" like peak current shape. The normal looking pressure dip has a "reclining arm chair" like shape to the peak current (both shapes are still different to the the "good" solenoids). This is definitely on every other turn on event. Then not long after(still at idle) the misfire goes away and the pulses return to normal and the "tick" shape current disappears then when the engine is revved an irregularity in the pulses can be seen once again with a direct relationship in the change of the peak current shape. Still with the every other event pattern.

As rightly pointed out in your pic (overlapping posts again)
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Re: Alfa Romeo MITO P1062

Postby STC » Sun Aug 20, 2017 10:56 pm

that every 8th pressure waveform has a "valley" missing it is just a large upwards slope? tends to suggest that particular cylinder is not pulling the same amount of vacuum as the others on every other 4 stroke cycle?


That is messing with my mental health too !! As you say Every Other Cycle ??!! That cannot be ?? I am not so sure that this is a solenoid fault anymore either. Perhaps an Interfered Command.
Multi Air 2.jpg

As we can see from the Purple Arrow something is occurring every 4 turns of the crank so 1/4 crank speed (RPM).

It is too accurate and regular to be coincidental.

I would now consider taking the auxiliary belt off, Blower and Fan Motor Fuses Out - And scoping anything that rotates or is pulsed such as a throttle Body.
Wheel Speed sensors in a particular gear .... .... ....
KV's
Oil Pump and supply lines ?????
...

You will either chase your tail or make a massively rewarding diagnosis.


In light of this, measuring Voltage command may explain Current irregularities.
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