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Thread: 3A90 Intake valves stuck open, carbonized, full of gunk and car won't start

  1. #91
    Quote Originally Posted by ahausheer View Post
    I can't recommend you do anything against the owners manual, but no, I do not think the California engines are set up differently. I just think for cost, legal, or emissions reasons, Mitsu didn't bother to certify it in America as e20 compatible. The engine specifications thread on this website specifies its E20 compatible as does public marketing material from a few other countries.
    California has had different emissions equipment for as long I recall.


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        click to view fuel log View my fuel log 2014 Mirage SE wussie cvt edition. 1.2 automatic: 37.7 mpg (US) ... 16.0 km/L ... 6.2 L/100 km ... 45.3 mpg (Imp)


  2. #92
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    Quote Originally Posted by Fummins View Post
    California has had different emissions equipment for as long I recall.
    I didn't think that was true any more, maybe I'm wrong. Thought all OEMs (for cars sold in the US) simply decided to build all vehicles to comply with the strictest emissions standards, IE, California. Do you know of any current Japanese oem examples or even current Mitsu examples who's engines are modified for California emissions compliance compared to the rest of the USA?

    Even if true I would be surprised if it made a car that is otherwise e20 compatible in many global markets into one that can technically only handle e10. Open to your feedback.

    Side note - CA cars can run at least one tank of approximately e30 without exploding, at least my old girl can. Not sure about 2 tanks though.
    Last edited by gone.a; 08-04-2020 at 05:07 AM.

  3. #93
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    Quote Originally Posted by Fummins View Post
    Good to know?
    Attachment 18848
    Now tell me there are 48 states and I'll be happy lol

    I wouldn't doubt if many engines aren't changed to appease California, but I would be surprised if Catalytic converters were the same in California as other parts of North America. Even my 2020 Kawasaki Sxs would come with California emissions if sold in California.....Looking something up, it's not hard.
    Fummins - I appreciate the wealth of info you contribute to this forum as it has helped me significantly with my own vehicular decisions, but sometimes, you come off like a jerk.

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  5. #94
    Quote Originally Posted by ahausheer View Post
    Fummins - I appreciate the wealth of info you contribute to this forum as it has helped me significantly with my own vehicular decisions, but sometimes, you come off like a jerk.
    I can't argue with you there. I may be slightly too sarcastic at times.... I'm working on that. Covid and alcohol withdrawals made me intolerant or something.
    Mirage videos:

        __________________________________________

        click to view fuel log View my fuel log 2014 Mirage SE wussie cvt edition. 1.2 automatic: 37.7 mpg (US) ... 16.0 km/L ... 6.2 L/100 km ... 45.3 mpg (Imp)


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  7. #95
    Senior Member AtomicPunk's Avatar
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    Quote Originally Posted by Fummins View Post
    I can't argue with you there. I may be slightly too sarcastic at times.... I'm working on that. Covid and alcohol withdrawals made me intolerant or something.
    I'm sorry, but I won't tolerate intolerance.

  8. #96
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    Quote Originally Posted by foama View Post
    @Dabullfrog91: The carbon incident of 2016 (see first post) was a freak event. It happened to mine and several other identical cars that filled-up at two particular fuel stations. No similar problems since, and the valves remain clean ever since.
    How fast? These cars don't have much acceleration, but are fast enough to keep up with the average traffic in the fast lane of the German Autobahn, and thats fast enough for me.


    UPDATE September 2018:

    The valves look clean, just as clean as last year.

    The cause for the incident must have been a tank full of bad fuel.


    UPDATE September 2019

    Valves look just as clean as ever. Perfectly clean, just as inside combustion chambers.

    However, ever since the car was "repaired" and carbon removed, the compression has been much lower at around 9bar (about 130 psi) on all cylinders, and fuel consumption is consequently about 10% or so higher than before.
    This car has a compression ratio of 11.5 : 1 and so compression should be much better.



    UPDATE August 2020: IT HAPPENED AGAIN!

    Until very recently the valves looked clean as new.
    It happened again! Last week the car wouldn't start. It had been resting in the garage for a few days after a long drive on the autobahn, just as in the first incident in post 1. A quick compression test showed almost nill compression on two of three cylinders, and very low on the third. Looking with the endoscope the intake valve stems were seen full of brown or black-brown gummy sticky goo and therefore could not close all way. Valves open means no compression means no start.

    Since the warranty had expired years ago, I repaired it like this:
    The intake manifold was removed and three new aftermarket gaskets manifold-to-head bought.
    I stuffed a narrow strip of cotton rag saturated with acetone into the intake hole leading to the valves of the first cylinder and added some acetone to it about every few minutes. After a half hour or so removed the rag and saw the gunk had softened. With a bundle of cable ties wrapped together as a tool, the gunk was mechanically scratched off, adding a little acetone every minute or so while doing it. Put the rag back into the intake, repeatedly added acetone, repeated the entire procedure again a few minutes later. Did the same on the second cylinder. When turning over the engine by hand, I could tell the valves were now moving properly. Some of the goo was still there, but most gone and the remaining much softened. Put everything together quickly, started the car and drove off to fill up the half empty tank with some fresh fuel. Checked it a few days later and everything looks perfectly clean again. Compression is unchanged as after the first warranty "repair" see first post of the thread.

    A chemical engineer explained to me that E10 fuel (10% alcohol) plus acidic greasy combustion products cause exactly that sort of residue. I didn't really understand what he said, but understood it had something to do with chemical reactions, the higher alcohol content of the fuel, and the blow-by reentering the intake. Although the car uses practically no oil, I ordered a little catch can that might help condensing some of those combustion byproducts. It will be intalled in the 10mm hose between valve cover and intake manifold. I wonder if it makes any difference...




    UPDATE: CATCH CAN

    I installed a catch can and tested it.
    It does collect oil at a rate of about 4cc every 1000km.

    There will be an extra thread about that.
    Last edited by foama; 09-01-2020 at 08:22 AM.

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  10. #97
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    Quote Originally Posted by Eggman View Post
    Of course, and I mention that it doesn't necessarily apply to your situation.

    But it makes me wonder how it happens to your 3A90. Could it really be a single tank of bad gas, or is it possible that it is an accumulation over time that doesn't become a problem until... ? Just speculating.

    I've been following the phenomena of intake valve carbon fouling more lately as I look to replacing an aging car in the driveway. Crazy how carbon fouling is affecting so many engines and interesting how owners and shops are addressing the problem. The BMW crowd has a neat solution with the walnut bead blasting through the intake port. But as we all know this shouldn't be a problem in this day and age of advanced engineering.

    And bummer that it's happening to you.
    That's what i'm wondering too.

    I wonder if this issue is more common to a specific regional fuel type blend in Europe vs. North America / Asia?

    Have any people outside of Europe experienced this issue?

    Almost all of the Gasoline here in Canada is E-10, so one would assume we should be having similar issues here if Ethanol is to blame.

  11. #98
    Quote Originally Posted by AtomicPunk View Post
    I'm sorry, but I won't tolerate intolerance.
    I meant incoherent not intolerant.
    Mirage videos:

        __________________________________________

        click to view fuel log View my fuel log 2014 Mirage SE wussie cvt edition. 1.2 automatic: 37.7 mpg (US) ... 16.0 km/L ... 6.2 L/100 km ... 45.3 mpg (Imp)


  12. #99
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    Congratulations on your repair.

    I do suspect that both instances of intake valve deposits were probably caused by bad fuel. Your theory about the fuel tanker being polluted by a previous load is one possibility. Another is that fuel is being intentionally polluted by dilution with some other chemical, probably an agricultural use fuel on which there is less tax. I have read of this happening in Ireland where gasoline/petrol fuel is diluted with agricultural use diesel fuel. I don't know how fuel quality testing is done at the fuel pump in Germany.

    I am somewhat perturbed by your loss of compression pressure though, as I believe this may be caused by a change in camshaft timing. To remove the intake valves and clean them, your garage would have had to remove the cylinder head and camshafts, so there is the possibility of it being assembled wrongly, and this could cause a change in compression pressure, and then also a change in fuel consumption.

    My service manual only covers my 1.2 engine, so I don't know if the 1.0 has variable valve timing like the 1.2, but I would expect it does.

    As you obviously have the skills to clean your intake valves, you should be able to measure your camshaft timing and verify it is set correctly. Another more remote possibility is a problem with the variable valve timing, but I would have expected the cam and crank position sensors to have detected this.

        __________________________________________

        click to view fuel log View my fuel log 2014 Mirage ES 1.2 manual: 46.0 mpg (US) ... 19.5 km/L ... 5.1 L/100 km ... 55.2 mpg (Imp)


  13. #100
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    Answers between the lines:

    Quote Originally Posted by mpaton View Post
    Congratulations on your repair.

    I do suspect that both instances of intake valve deposits were probably caused by bad fuel.


    Agreed!

    Your theory about the fuel tanker being polluted by a previous load is one possibility. Another is that fuel is being intentionally polluted by dilution with some other chemical, probably an agricultural use fuel on which there is less tax. I have read of this happening in Ireland where gasoline/petrol fuel is diluted with agricultural use diesel fuel. I don't know how fuel quality testing is done at the fuel pump in Germany.

    They do check in Germany, especially the tax authorities, but nobody wants to even think about getting in trouble with them.

    I am somewhat perturbed by your loss of compression pressure though, as I believe this may be caused by a change in camshaft timing. To remove the intake valves and clean them, your garage would have had to remove the cylinder head and camshafts, so there is the possibility of it being assembled wrongly, and this could cause a change in compression pressure, and then also a change in fuel consumption.

    I thought so too. Cam timing is thoroughly checked and OK.
    When it happened the first time, the dealer repaired it. Maybe the piston rings were gunked up too? I don't know, and they were not taken out during repair.


    My service manual only covers my 1.2 engine, so I don't know if the 1.0 has variable valve timing like the 1.2, but I would expect it does.

    The 1.oL has shorter stroke but otherwise identical.

    As you obviously have the skills to clean your intake valves, you should be able to measure your camshaft timing and verify it is set correctly. Another more remote possibility is a problem with the variable valve timing, but I would have expected the cam and crank position sensors to have detected this.



    Last edited by foama; 09-05-2020 at 05:47 PM.

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