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Quota1100ES - big fuel consumption and choking

Discussion in 'Quota & TT' started by dera, Jul 19, 2015.

  1. dera

    dera Just got it firing!

    Jul 19, 2015
    Likes Received:
    I'd like to get some help with my MG Quota ES1100 1999year, on injectors of course.

    there are two main problems:
    - to much fuel consumption, aprox (I'm listing values in the three standards: Europe/UK and US :))
    from 7.5 to 8.5l/100km
    or from 33 to 37,5mgp (UK)
    or from 27.5 to 31mpg (US)
    I know that it shoud take from 5 to 6.5 l/100km- not more.

    - engine chokes and interrupts. When crusing at 3000rev (on every gear) it chokes, doesn't work smooth but has interrupts - it's so annoying

    - when it was cold (lower than 10 celciu degrees) it was starting very hard, I couldn't touch a throttle for about two minutes because it stops immediately. After it was warmed up - it was warking quite vell (of corse it was choking and

    so on - see the FIRST and the SECOND problems :)) Now it is summer in Poland so I don't have problem with starting but I assume it is going to back when the weather is colder.

    Ok - now my findings:

    I have been fighting with this issue for a half year (I have this motorcycle for a half a year and previous owner said that he also had problems with choking and too much consumption):
    - I changed oils/filters
    - I set tappets clearance (0,1mm inlet, 0.15mm outlet)
    - I replaced sparkplugs and sparkplug caps
    - I chekced the throttles synchro with carbutune pro - everything is ok - on 3000revs vacuum is synchronized on both cylinders
    - I checked the cylinders compression - it was identical for both cylinders
    - I checked a fuel pressure - it is ok both when engine is working and in the first phase when only a fuel pomp is working
    - what's more - I've recenlty installed the M18 weld-in bosses to install a lambda sensor to measure AFR - just for testing. I installed the bosses on the exhaust manifold, about 20cm down to the cylinders - and now I'm able to meassure AFR on the both cylinders, the results are in the jpgs-attachments. On the jpgs are are the logs from the two test drives when I was cruising 3000revs/min on the fifth gear. You can see that the left cylinder has bigger AFR (mixture leaner) than the right one - especially when idling - the LEFT is idling on AFR=15 and the RIGHT is idling on AFR=12.5). During riding the LEFT one is still leaner (difference in AFT when cruising 3000revs/min is minimum 1).
    Regarding AFR: I swapped the left and the right injectors - but the left cylinder was still leaner. I swapped the left and the right coils including high voltage cables and still the left cylider is leaner (so - not problem with injector nor coils). I also installed new exhaust manifold gaskets - but the result has't changed.

    - TPS. I've tried only two or three seting on TPS - so It's not an area I have explored completely. I started from 150mV when butterflies were fully closed (as a servicebook said). It was about 313mV when idling. Fuel consumption was about 7.5l/100km and engine was choking and interrupting on 3000rev/min.
    Then I set TPS to 430mV when idling - consumption increased to 8.5l/100km but the engine started to work in the perfect manner - It wasn't choking nor interrupting. But the consumption is too big.
    Now I set TPS to 375mV when idling - I don't know the consumption yet.
    - another word to TPS - when I'm tampering with the TPS on the runngin engine - I can see that if TPS i set below aprox 350mv when idling - then the engine is choking when I'm holding it on 3000revs/min. When the TPS is set above aprox

    350mV then the engine is working smooth, without choking when holding on 3000revs/min. I wasn't observing a vacuum synchro when I was tampering with TPS - maybe I should be doing that?

    What do you suggest?
    My results show that there is something wrong withe the left cylinder - it has problem with compression leak (piston rings or valves)? Or maybe with some false air in the inlet manifold (but Carbutone shows that vacuums are equal on both cylinders).

    This is link to movie where my Quota is choking: drive.google.com/file/d/0B1_dnXFLfaMbUDYtLUdmb2ZSR1U/view?usp=sharing
    see somwhere from 10s of the movie, the engine is choking and revs are decreasing. You can hear tick, tick noise and the revs are decreasing in these moments...

    Ok, sorry for that little long post, but maybe someone has some wise ideas.

    Kind regards,

    Attached Files:

  2. john zibell

    john zibell Moderator Staff Member GT di Razza Pura

    Oct 28, 2008
    Likes Received:
    Huntsville, AL
    For TPS settings take a look at the PDF here http://mphcycles.com/the-pdf-mike-sent-that-i-dont-know-what-its-about-write-a-real-title/ Also this http://mphcycles.com/tuning-the-guzzi-efi/ Pay particular attention to the last paragraph.

    If you have access to diagnostic software, make sure the air and engine temperature sensors are in range. Most starting and running problems are a result of faulty reading sensors. If you don't have access to software, the P8 manual will help you get resistance for temperature data.

    Attached Files:

  3. Akadak

    Akadak Just got it firing!

    May 9, 2016
    Likes Received:
    ADK Mts.
    I too have had starting issues you stated. Most likely a sensor as John said. So far I have just delt with it. When it happens I turn ignition off wait a minuet then try again. Using the start/lever makes it worse, not even a pop.

    Have you checked for intake leek on the lean side? Change the fuel filter?

    I also DO NOT drive my bike In 5 gear at 3000 rpm. The motor does not like it at all.
    Drop down to 4th and 4000+. The ride should be much better.

    As for my fuel milage I get 42 mpg and have gone almost 200 miles with out running out.

    Good luck. Ak

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