Correct, The OE ignition system does not provide multiple sparks. However, which I should have mentioned in the beginning, this has a Crane Fireball ignition controller. I believe it is a HI-6S Digital Multi-Spark Ignition (an inductive design).


OK, that makes more sense. When I first saw that I was disturbed by it and I did not get passed that. Wow, this is an inductive Multi-Spark ignition system and not a capacitive ignition system? Very interesting. Does this system only multi-spark at idle? Is this to achieve a smoother idle?


No need to see the coil current ramp.

Maybe, just for fun.

The problem is isolated to one cylinder as seen in the movie. From left to right, the firing events are 5718436572. This is using #7 as a sync because it was easiest to get to. A faulty coil would have shown up in other cylinders as well.

Like I said before I could not get passed the multi-spark. Would the firing events be 57218436572? I never thought it was a faulty coil.

You want to see ignition control? You did. I think what you meant was ICM inputs, correct?


Yes that is correct. I wanted to see if the inputs match the outputs.


Now its time to determine from the secondary ignition capture of where the fault is based on the irratic spark line disturburbances.


The problem is in cylinder number 5. I see good conductivity at the start of the firing line and normal spark KV. At first the air fuel ratio is normal but some where in the middle there is a lack of conductivity. It does not look like it is running lean to me but rather a lack of HC and 02. I think it may be a mechanical problem on the cylinder. I would want to hook up a vacuum gage or use the First Look sensor to verify if this is the problem.  Depending on the results I may do a cranking and running compression test.   

Edwin

With the firing order of 18436572 and the pattern being synced/triggered by #7 cyl, I believe at this point that #5 is exhibiting a fuel distribution issue, and the First Look sensor is not indicating a restricted flow to any cylinder, I suspect a faulty /poor spray pattern from that injector.

Edwin -

Your observations on the fuel trim numbers may be correct.  But I think that they could be caused by an ignition misfire. 

First, the fuel trim numbers are from the vehicle accelerating under load on a test drive (do we know only one cylinder was misfiring at the time?).  The secondary ignition waveform was captured at idle (do we know what the fuel trim numbers were at idle?).

Second, the short term fuel trim for bank 1 really wasn't that high (133).  This could be easily be caused by a single cylinder misfire.  I could be completely wrong here, but I believe that the high long term trim for bank 1 is showing the cumulative effect of the misfire over a long period of time.  In other  words:

Misfire occurs --> O2 swings low --> More fuel added (short term nudged slightly higher) --> Long term follows and is nudged higher --> 

Misfire occurs --> O2 swings low --> More fuel added (short term nudged slightly higher) --> Long term follows and is nudged even higher --> etc.

Of course each time fuel is added it actually does more harm than good since the cylinders don't need more fuel.  It is just that the O2 sensor sees excess unburned oxygen and doesn't see the unburned HC's from the misfire.  So, the computer responds by over fueling.   Additionally, this actually makes the engine run worse since it now has gone from having one cylinder misfiring due to an ignition fault to now having four over fueled cylinders.

Though I must add that I would be the first to admit that my understanding of fuel trim diagnosis is not as good as I would like it to be.

loren

Edwin,

I need to elaborate on something here. I pulled those idle trims numbers off of the tail end of my recording. This was after a decel sitting at the intersection ready to make a turn. My focus was more on traffic rather than how the engine was running at the time. It is very possible that the engine was running ok at that time. I wasn't watching trims at the time I captured secondary. The idle instability was not consistant. I'm not so sure I could pick out an intermittent misfire using fuel trims regardless. No, I didn't attach a vacuum gauge, but that is a very good suggestion. Something very basic that often gets overlooked even by me. I assure you there was not a mechanical issue. When I seen the ignition capture, one thing came to mind. There is a ____ to ______. What is your method of converting counts to percentage regarding fuel trims?

Man, I was hoping you guys didn't catch that rotor KV being higher than plug KV on that first event. Anybody want to take a stab at it? It doesn't happen during the next firing of #5.

Romain, take a look at the third strike on the first series of strikes for #5. Poor injector spray pattern?

No, you didn't get wrong information. What I said is true. It did have a lumpy idle and the trims I gave are correct. I should have mentioned the lumpy idle was intermittent. Sorry, that is my fault. I did see where you drifted off the right path is why I mentioned it. You are doing real well with this Edwin, I'm glad you joined in on this post. My apology for misleading you.

Wouldn't you agree that FTs would not necessarily reflect an intermittent misfire?

Hi All,
        
     I am not a fan of secondary ignition diagnostics. I am of the firm belief that one thing can look too much like another.

     When I look at the #5 pattern it looks like to me it could be caused by a poor injector spray pattern. (as Romain pointed out)

    When I look at the #5 pattern it looks like to me it could be caused by EGR turbulence (as Romain pointed out)

    When I look at the #5 pattern it looks like to me it could be caused by turbulence from a valve sealing issue. (as Romain pointed out)

    When I look at the #5 pattern it looks like to me it could be caused by a loose spark plug.

   When I look at the #5 pattern it looks like to me it could be caused by carboned valves soaking up fuel on #5.

   When I look at the #5 pattern it looks like to me it could be caused by maybe something else that doesn’t occur to me. 


   Personally the only thing I believe it’s possible to see for sure in secondary ignition patterns are patterns of normal, high and low resistence.

    When I take a look at #5 pattern all I feel confidant in saying is that I see high resistance in the burn line. However since Carl seemed to highlight the rotor gap I’ll do what I don’t like to anyway and take a SWAG and say:
   
       When I look at the #5 pattern I see high resistance in the burn line that looks like to me it could be a crossfire to another cylinder ......or it could be something else that doesn't occur to me.

       If block learn of 128 is 0 LTFT then I guess 158 / 128 = 1.23 would mean an LTFT of +23% ? The clues from the block learn if Edwin and I are doing close conversions sure don’t add up though. I'll have to go along with Edwin here. A +23 or +26 sure indicates a lambda issue that could easily be single cylinder lambda related misfire. Maybe this truck has another bank 1 issue totally unrelated to the misfire. I don’t see an ignition misfire causing this much +LTFT

    Darn! I hate trying to do this with secondary patterns. They make me SWAGGER 
   
    Personally when it comes to misfires give me a vacuum guage,O2 waveforms, and most times FT’s (but even better a gas analyzer) any day 

Hi JT,

Nice to hear from you.  I know you and me have traveled this road before about secondary ignition wave forms.  You definitely make really good points. 

Carl, I like to use fuel trims and a vacuum gage for misfires to give me a direction where to go.  You asked if I used fuel trims for an intermittent misfire, that would depend...  If the system cannot give you fuel trims, I like to use the gas analyzer along with a vacuum gage and the O2 sensor.  You didn't give me the wrong information, but the way you presented it, it made it seem to me that those fuel trim numbers were happening at the same time as the misfires.  In order to use fuel trims for misfires the misfire has to be happening at the same time.  The way I was calculating fuel trim as a percentage was like John is calculating it, except I was using total fuel trim.  Definitely John put it the best way by saying that this is a SWAG because we don't have any fuel trim numbers, vacuum readings, or gas readings.  So if I was to take a SWAG at it now, I said you have a possible ignition misfire and it cross firing to another cylinder under load and maybe two cylinders are misfiring causing those high positive fuel trims under load.  Is the rotor gap the same in the other cylinders?  Can you give us more detail?  Can you post the secondary during the acceleration?

Edwin