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Decarboning

Discussion in 'CARC' started by double.d, Aug 25, 2010.

  1. double.d

    double.d Cruisin' Guzzisti GT Contributor

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    After installing the PCV-Autotune on the Griso it gradually began runnung a lot richer, to the extend where you could see black smoke at idle and it also started pinging. After having the rich running part rectified ( that's another story, thanks Mike.C) i am left with the motor pinging, and would like to work at solving this problem.

    Two topic posts i have read recently gave me two starting points to work from,
    1. The use of 10-60 oil instead of the 10-40 i am using now.
    2. Carbon build up on the pistons and valves, which i am sure would be the case since the motor has run way rich for 12 months.

    The oil part i have sorted but can anyone suggest the best safest way to decarbon the inards ?
     
  2. DanPez

    DanPez Cruisin' Guzzisti

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    Hey double.d,
    Fuel has a lot to do with the pinging ......but decarboning
    I always heard opening the engine up under load helps. (Highway driving)
    I actually do this on our (town vehicle) and therafter feel the difference ...... but never opened the heads to physically check!
     
  3. GTM®

    GTM® Administrator Staff Member GT di Razza Pura

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    "Gradually began" -- ??
    The programming I suggested is much richer then (critically lean as delivered in) stock trim, yes. However, it is for better power and cooler running. If you are not happy with it, simply adjust the AFR's in AutoTune. I do not recommend much higher then 13.8, and I suspect a great deal of pinging will be back if you do, along with warmer engine temps. Try it, and post again.
    Also, do keep in mind I have well over 100k miles on my Jackal motor using 13.2 AFRs, with ZERO issues, in running or with carbon build up, etc. You can ask anyone who has ridden it. Don't be critical about it, as I've done the research for you, just ride and enjoy it.
    :silly:
     
  4. double.d

    double.d Cruisin' Guzzisti GT Contributor

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    The auto tune module has never worked until we just recently found the problem. During this time it began running richer to the extent that the rear end of the bike was covered in soot and you could see black smoke at idle. The 02 sensor was caked with soot as well.

    When the auto tune was fixed i set some of the afr's to 13.6, but have since set them all at 13.2 and have done a few hundred k's since then, so plenty of time to adjust. The % changes when i plug in the software are now minimal so all is working ok and i am now working on a map for each month of the year to take into account changes in temperature.

    Before the PCV was fitted i could get the motor to ping by using 91-93 octane fuel. I used this only when 98 was not available. I fill with only 98 octane and have tried various outlets.

    The motor pings in 3rd gear up under load so i am discounting the fuel theory, and looking at any other external option. Due to the length of time the motor was running way rich i figured there must be some serious carbon deposits in there.

    95% of the riding i do is out in the country with cruising speeds of 130klm +.
     
  5. DanPez

    DanPez Cruisin' Guzzisti

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    As mentioned its not a critical issue ...... you've taken a look at the plugs? (Their clean?)
    As you said having access to the O2 sensor gives you an good indication of the carbon deposit ....
    As an option....
    Like Todd mentioned you can try running the AFR a little lean this will heat up the engine more and eventually remove the soot. (checking the sensor condition.... occasionally)
    If you push the bike hard you'll be hearing pops from the engine .... under compression ..... giving you an indication your running lean!

    Once you see the sensor is cleaner and plugs have no accumulation you can work on the mapping.
    Cheers!
     
  6. double.d

    double.d Cruisin' Guzzisti GT Contributor

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    So what you are saying is that if the plugs and 02 sensor look good now there will be no carbon evident on the pistons and valves. :cool:

    I went to hoon's superstore and bought a fuel additive for FI engines that breaks down carbon and cleans the fuel system. I figure it can't do much harm :geek:
     
  7. rturo

    rturo Cruisin' Guzzisti GT Contributor

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    Blimey.. I last decoked an auto engine about 25 years ago. It needed it but it was high mileage and built to 60s/70s tolerances and running the basic oils and fuels of the day. I was under the impression that a lot of the coke in those days was from oil getting into the combustion chamber.I now expect (hope :D ) modern tolerences, synthetic oils and modern fuels with cleaners in them keep things sweet and hope coking up is a thing of the past!

    I would be surprised if the rich fuelling you have been experiencing on a modern engine (yes I know its an air-cooled Guzzi but still modern relatively speaking) would have led to much coking up.

    Like you I'd try a dose of cleaner in the fuel (I use it lightly diluted - a 10 gal treatment in a couple of gallons in my diesel car to clean the injectors for the annual emissions test and it works a treat, then fill the tank with fuel to dilute it to normal strength). Then just monitor things now its running as required.

    If I wanted to be certain one option I just found that I might consider before a strip down is an inspection camera used through the plug hole, either pay any auto shop who had one (2 plugs out, inspection and plugs back can’t be more than an hours work max) or might even consider buying one... look at this in the US - http://cgi.ebay.com/ebaymotors/Snap-On- ... 645wt_1252. Worth doing if it saves a stripdown.

    Don’t know if it’s a concern for you but I recall reading a while ago that catalytic converters are very sensitive to overfueling and can be damaged... wouldn’t bother me if it didn’t affect the running as I’m still looking to ditch the cat on my Breva1100.

    Hope all is well and keep us posted.

    Art
     
  8. GuzziMoto

    GuzziMoto GT Reference GT Contributor

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    Some of those work and some don't. Either way, you may want to consider removing the wide band senor for the Autotune while running the cleaner.
     
  9. double.d

    double.d Cruisin' Guzzisti GT Contributor

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    To late, already done. made no difference.
     
  10. Mi_ka

    Mi_ka High Miler

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    ... for now - the problem is you can never be sure about the health of a wideband sensor ...
     
  11. GTM®

    GTM® Administrator Staff Member GT di Razza Pura

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    Which was? There is a test you can run using the AutoTune module to test the sensor... though it sounds like it is working OK now(?).

    Andrew/SpaceClam has a similar problem on his G11, and he went as far as to mill the heads to adjust the squish. It helped in performance, but not pinging. You should do a search... he was more focused on heat and thermal coatings to resolve it, though he hasn't to date. Hope that helps, keep us posted.
     
  12. Mike.C

    Mike.C GT Reference

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    I haven't wanted to shove my oar in on DD's thread, but there seems to be a bit of misunderstanding of the problem caused by confusion with AT and rich running problems so maybe I should set the record straight.

    Dave called me to see if I could help get his PCV to run right as he wasn't able to get the AT trims to work, so one Saturday a month or so ago he brought his Grisso round.

    When we had a look, it was obvious that something was seriously wrong with the fuelling, the exhaust pipe looked like one from a MAC truck it was so black with soot.

    Hooked up the PCV software on my pooter that I know works and eliminated his computer from the picture as the readings on my computer were identical to his. After a bit of head scratching I ran the O2 test sequence and it came up "problem", so pulled the O2 sensor to do a swappsy with a spare that I have.

    Now here is the thing, I am surprised that the exhaust could get out of the motor at all with the amount of soot that was all over the sensor. Without a word of exageration, it looked like the inside of a London tenament chimney from 1830 that had not seen a chimney sweep for 30 years and even Mary Poppins would not use :dry:

    So what was certain at this point is that the fuelling was way too rich and given that the bike didn't run like that prior to PCV install the combined PCV/AT/revised GT ECU Map was definitely not working right.

    Assuming that the O2 sensor was bad we tried to replace it, but found that the new spare I have has a bad thread and we couldn't get it to start in the exhaust bung, (I will have to get a thread chaser to fix it at some stage, anyone know what the thread specs are? .... another job added to the list :cry: )

    Eventually while I was poking around at the wiring for the AT module I found the problem. The small blanking plug required in the spare port on the AT had come out, stuck it in and all was good.

    So having thought about it since, the rich running problem was caused by the combination of a changed map in the ECU and a map saved in the PCV that I presume came pre-installed in the PCV running on top of that with no AT correction.

    It would not surprise me if there was a lot of carbon in the cylinders given the state of the O2 sensor and exhaust, and certainly some carbon hot spots in the combustion chamber might cause some pre-ignition of the fuel charge that would show up as "pinging" but my experience of that sort of thing is from de-coking Honda XL500 dirt bikes in the mid 80's and so a fuel injected modern engine is outside my ability to comment and I'm interested to hear the outcome of this thread.

    So to get it absolutely straight, the rich running and pinging were two separate issues but the pinging may now have an added causing factor of carbon as a result of overly rich running.
     
  13. double.d

    double.d Cruisin' Guzzisti GT Contributor

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    Thanks for explaining that Mike. I have saved 5? Maps since you sorted it and all seems to be working well with most variances under the 10% range.

    I pulled the plugs before running the fuel additive and they were both white. I ran the full tank with the additive through and there was no difference that I could discern.

    I know it probably won't make any difference but as a last resort I am going to put the Staintune back on and return the air box lid to original.

    Other than that when it gets to hot to ride I will send the ecu over to Todd for a bit more manipulation.
     
  14. DanPez

    DanPez Cruisin' Guzzisti

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    I found this very good explanation from Spaceclam concerning pinging:
    https://www.guzzitech.com/forum/topic. ... ion#p18168
    This may help for the adjustments of your AT and type of fuel you use.

    If a product is used for decarboning it would have to be specially blended for fuel injection systems ..... for the O2 is an Electro-Chemical sensor .... any strong chemical product used to clean may and will deteriorate the sensor response.
     

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