TuneECU Injection Pulse reading - Screenshot

Discussion in 'Crazy-Awesome almost Dakar racers (950/990cc)' started by BigTony, Oct 30, 2012.

  1. BigTony

    BigTony Been here awhile

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    I'm trying to diagnose some rough running on my '07 990 adv. At idle the exhaust at the left pipe seems to be sputtering and weak. I already set the TPS to .57-.58v hot and sync'd the TBs as best as possible by matching the TuneECU map values at idle.

    I was checking with tuneecu and I see the following:
    http://www.flickr.com/photos/89427113@N03/8140337285/in/photostream/lightbox/
    [​IMG]

    Given that there seems to be a difference in how the two cylinders are running, based on the exhaust feel and sound, the two different values for 'Injection pulse' seem to jump out. ~2.6 on the left value and 3.1 on the right value. I also noticed when I first started the bike the O2 reading on the left read consistently lower than that on the right.



    Does anyone know if this is normal? Anything I can check/test?
    #1
  2. Zuber

    Zuber Zoob

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    First, you should post this on the TuneECU thread.

    Have you flashed a new map when this happened? My first map push from TuneECU was a bad one and it would run on one cylinder. Just pushing the map again fixed it and it ran fine.
    #2
  3. big-t

    big-t Been here awhile

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    It appears your 02s are not disabled,so I would look for an air leak on the cylinder with the higher PW reading.
    The 02 sensor is seeing more air and ramping up the pulse width in an attempt to correct.



    + what Zuber posted..
    #3
  4. BigTony

    BigTony Been here awhile

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    Ah good feedback. Sounds like a couple of tests might help:

    -Load the open exhaust map w/ o2 disabled and see if the cylinder still feels weaker
    -Re-load the stock map and see if the issue is still there
    -See if there are any exhaust leaks at the header pipes (I did remove and remount those recently)

    Anything else I should check?
    #4
  5. big-t

    big-t Been here awhile

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    While running take a long pair of needlenose pliers and squeeze off all the vacuum lines to the affected cyl while watching the pulse width.Also check the SAS for leaks at that cyl.
    #5
  6. BigTony

    BigTony Been here awhile

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    Just had a few min to do some checks...

    I loaded up the akrapovic map and found that the sputtering from the left pipe stopped, however the exhaust pulse still felt stronger (just subjectively on my hand) from the right pipe. I'd have sworn they always felt about the same in the past but I don't remember really thinking about it before, so I don't know if this difference is normal or not. I really wish I knew if the difference is normal... (the bike does have leo vince pipes w/ an h pipe, so who knows). The injector pulse reading in TuneECU was still longer for cyl 2 than for cyl 1 with this map. With this map, cyl 1 MAP read about 20hPa lower than cylinder 2 at idle, but they're matched with the stock map - not sure if this would mean anything.

    I used in IR thermometer and the front cylinder header is about 20degrees warmer than the rear but they're pretty close with either map.

    I then re-loaded the stock map and the sputtering in the left exhaust pipe returned.

    I noticed in TuneECU that my voltage drops from about 13.1V to 12.5 when the fans come on. I saw it dip as low as 11.8 at one point. As the bike runs the O2 voltage would typically be in the .75-.8V range for both cyl but would drop to virtually 0 occasionally. I was looking to see if it correlated with the voltage drop when the fans came on but couldn't really tell if it happens around the same time or not.

    Next up will be to try big-t's suggestion of squeezing vacuum lines... not sure if I'll be able to access them with the airbox on or not but we'll see - definitely a good idea.

    In the meantime - anyone have any ideas as to why the injector pulse would still be longer with the akrapovic no-O2 map loaded? I guess this could suggest some leak in the vacuum hoses huh? Do you think my voltage drop when the fans come on is abnormal (ie - do I need a new battery?)

    THANKS!!!!
    #6
  7. Dusty

    Dusty Long timer

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    I don't think they will feel the same.

    How old is that battery... it looked fishy in your screen shot...
    [​IMG]

    This is one of my first screenshots
    [​IMG]
    #7
  8. DirtJack

    DirtJack Adventurer

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    I have. A Signal dynamics voltage meter on my 990 and a new battery and a second fan. I notice a voltage drop to about 12.1. When the fans come on.
    #8
  9. BigTony

    BigTony Been here awhile

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    Hey Dusty thanks for the comparative screen shot!! That is very helpful and it does look like your O2 values are much more even. Mine are crazy because they'll just drop all of a sudden to almost 0 and then fluctuate a bit, then come back to the 0.7-0.8V range, then drop again, and the injector pulse doesn't really seem to move in lockstep with the O2 value. I really don't have any clue how to diagnose this other than fiddling with vacuum hoses at this point. I suppose I could switch the 2 O2 sensors and see if that makes a difference, but ugh I think I'd have to take the whole exhaust back off...

    So were you saying you thought that the exhaust should or shouldn't feel the same at the exhaust pipe?

    Dirtjack - thanks for the info on the voltage - I've got the 2nd fan also so maybe my levels are reasonably normal - at least not high on the list of possible culprits...
    #9
  10. Dusty

    Dusty Long timer

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    Mine will do that also with the o2s reading, they do a dance... i dont get it either.
    From memory i dont think mine felt equal from day one... different lenths of pipe, bends?
    #10
  11. BigTony

    BigTony Been here awhile

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    Thanks dusty - that gives some peace of mind.

    I read online somewhere yesterday that narrow band o2s are kind of binary and will typically flip from low to high voltage when the af ratio becomes rich or lean. So some fluctuation is probably normal there too when running on o2s.

    I tried a stethoscope and shooting some starter fluid around to look for vacuum amd exhaust leaks but nothing conclusive.

    It does seem like a vacuum leak is the most likely culprit based on the symptoms

    I noticed the vacuum hose that comes off of the t at the intake manifolds and runs to the pump under the dash is kinked a bit, but not leaking - I wonder if this could cause running

    One way or another looks like I've gotta start taking stuff apart to get access to those hoses
    #11
  12. big-t

    big-t Been here awhile

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    I wouldn't put a lot of faith in the o2 readings Tuneecu is showing because they operate much faster than it shows on the screen.Most diagnostic software just averages out the readings,so your not seeing a true picture of the o2 operation.You have to use a o-scope to get that.They can switch at up to 5 or 6 times a second depending on conditions.

    How about disabling the o2 s with Tuneecu and see if that evens out the injector pulse ?

    If it does I would bet on an air leak,maybe the SAS leaking air into the exhaust..at one of the cylinders..:hmmmmm or possible a dirty injector not atomizing the spray well enough for a good burn
    #12
  13. tahoeacr

    tahoeacr Long timer

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    I think your reading way too much into this. My exhausts were never the same either. Their different lengths and have a crossover. I'm reading this thread off my phone so I couldn't make out your screen shot to well. Injector pulse width should be different. Cal 1 is the rear and runs hotter do it should have more fuel. Injector pulse width is done in percentage of available time to open the injector. We are talking maybe 20 milliseconds here. If cylinder one is 2.6% and cylinder two is 3.1% we are talking about 1/2% of 20 ms. You injectors probably aren't even matched to within 3%.
    #13
  14. men8ifr

    men8ifr Been here awhile

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    I would guess air leak or the throttles are not balanced - or not close enough to get the pulsewidths very similar.

    Can you get a reading while riding the bike with more airflow going through the carbs?

    If you are happy there is no air leak there should be an adjustment to balance the throttles at idle (sorry 950 owner don't know the exact layout of the 990's) you could try adjusting that until the pulsewidths are the same. - also make a note of the idle is smother or not (should be smoother if you are balancing them). The correct way is to balance the air pressure at idle with pressure gauges of course...
    #14
  15. BigTony

    BigTony Been here awhile

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    Yeah I've come to find I think the pulse length being different is normal.

    The real problem is that the bike hunts around in RPMs at idle and there is a sputtering sound like it's missing from the left tailpipe. So I was just looking for anything in tuneecu that might help point me to the cause of this issue.

    I did turn off the O2s at one point and the sputtering sound does stop when I do that and the idle seems more stable but still not rock solid.

    One thing I noticed is that the rpm really drops and the bike seems to struggle after it warms up and I hear the solenoid click for the SAS pump at the back of the airbox. This wouldn't impact A/F ratio though would it? I thought it is just pumping fresh air into the exhaust - so why would it cause an rpm drop and the bike to start stumbling? hmm
    #15
  16. tahoeacr

    tahoeacr Long timer

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    The SAS does effect A/F ratios as it is upstream from the o2 sensors. One would think that when it is on the ECU would consider this. But then again KTM is not known for there fueling strategy. Take the SAS off. Sounds like your idle is too lean when warm. Two things you can do that might help. While warming up your bike track the temps of the radiator with your IR gun. Make note of the temp when the idle changes and what RPM it goes to. There is an idle map in TuneEcu you can adjust. Save your map. Load an Akra map and see if it idles well. If it does you can either cutand paste just the idle numbers on to your map or just go in and match them. Run your bike with TuneEcu open and watch what cells your in during idle. Most Akra maps are in the 12's from idle to 100%. Somewhere between the Akra numbers and your stock map is where you will end up.
    #16
  17. BigTony

    BigTony Been here awhile

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    Ah good info there TahoeACR - that makes sense about the SAS - it makes sense that pumping fresh air in front of the O2s would cause a change in overall AFR. Weird that this isn't compensated by the ECU tho. That is definitely the best argument to remove SAS. I told myself I wouldn't remove smog equip on this bike because I've always regretted it somewhat on previous bikes but I may just have to go that route here.

    I'll try your suggestions with the idle settings - sounds straightforward enough. It does idle better with the Akra map. The throttle body balance is also different with that map which I found interesting.
    #17