looks like it is trying to turn on the injector but no current is going through when it cuts out.  Is that something that would be in the injector winding?  If it was a open I would not think there would be voltage at the supply and contorl side at the same time.  Am I anywhere on the right track?

Hi Sam,

Would you agree that an injector winding fault will be more than likely consistent?

Also, I agree with your statement in regards to an open. We wouldn't see supply voltage on the control side if it were open. What if there was high resistance instead? Would this not show us supply voltage while the circuit was unloaded?

Hi Sam,

I sent you the psd file.  You can open it with the current software.  Just switch converters in the software.

If any other Pico users want to have a closer look:

http://www.autonerdz.com/downloads/mf.psd

         I have to admit I was confused by what thought I saw in the movie.  An engine that seemingly was running alternately between mostly four cylinders and no cylinders without rpm change? The download sure helped. The rpm was fluctuating! Blowing UP one signal sure helped me to see a problem.

          BTW don’t ever try to play Techardy with Matt. Nice guy nervousness but cool as a cucumber under fire   What a natural! Thanks for the cool capture Matt!

I read good pertinent stuff in a manual by Linder (of injector reputation) and in a waveform reference manual by Motor.
  Linder calls these injectors TBI injectors(TBI was a peak and hold injector in GM applications).I noticed ours have a pattern like the peak and hold.One injector fires all six poppets at once, thus ,once per revolution.I think the reference voltage is perhaps a modulated cam position signal -maybe a hall effect with six vanes-the injector would fire once per crank revolution.That would be why we see a consistent injector firing every third cycle of the reference voltage, once per crank revolution..SO, the signal for the injection for the cam position is fair to good.
         In the Motor reference manual is a case history of a bad peak and hold injector- the shorted injector ruins the driver. I think it looks like the injector in our case follows the pattern of a shorted injector because it has low or non-existant voltage peaks(That is the way MOTOR explains it)-they ought be consistently around fity or eighty volts depending on the system.Ours are all over the place.I could say it ruined the driver because of the way the driver is firing the injector(that is what happened in the case history -the shorted injector ruined the GM injector driver-new PCM time).It looks like the driver has no rhyme or reason to the way it fires the injector and it looks like the short is an intermittent that would only get worse.
 They put diodes in the COP spark systems in series with the secondary to prevent voltage surges from it going backwards into the PCM and shorting it.
                    This explanation is relative to the books I have read, but not due to practical experience.Practical experience can be embarassing.Go to open forum and read about mine today for sure.
   

Quote:


Fisher,

There are no signs of a shorted peak and hold injector in that capture. If that were to happen, we would see a quick vertical rise in current at turn on to about the midway point typically, and then ramp up at an angle to about 4 amps. Current limiting would kick in and lower it to approx 1 amp. This doesn't hold true for a saturated switch style injector. Since there is no current limiting feature with that type, we would see higher than normal current peaks accompanied by the quick vertical rise at turn on. You are correct in stating that the voltage peaks are dimished with a shorted P&H injector, however, we would still see current flow until it got to the point the driver shut down. Remember what Tom said, "everything is there to diagnose this vehicle." A shorted injector taking out the driver is not there. Hope this makes since.

What a great capture. 8)  Thanks Matt... It sure looks like a bad ECM driver to me.

Edwin