Bruce Amacker Posted February 13, 2011 Share Posted February 13, 2011 I was at a large training conference yesterday and struck up a conversation with one of the top instructors in the country, John Thornton. He told me about a difficult 6.0 he worked on recently. It was a no start and by the time he got there it had numerous new parts on it- ECM, FICM, sensors, harness, etc. to no avail. It had an extremely odd problem- not only would it not start, but the PCM would momentarily remove the ground from the starter control relay while it was cranking, causing the starter to audibly shudder and disengage momentarily. If the FICM relay was removed the starter would crank normally. John is one of the best scope guys I've ever met and relies on his scope as much or more than the scan tool. In checking the CKP and CMP signals he noticed a weird regular noise signature that would occur in all of the signals he scoped. He noticed this noise would occur regularly every 2 revolutions of the engine in the same spot on all scope patterns such as CKP out and CMP out, and quickly linked this to the firing of one injector. Unplugging the injector made the noise go away and the engine start! Replacing the offending injector solved the problem. Even John, who I respect highly, could not answer what was wrong with the injector to cause this EMI/RFI feedback into the FICM and piss off all of the processors to the point of a no-start. I'm just passing on a weird story in the case it helps someone in the future. Quote Link to comment Share on other sites More sharing options...
Keith Browning Posted February 13, 2011 Share Posted February 13, 2011 Mr. Amacker? Were there ANY other clues that would have led to this diagnosis such as DTC's or PID data? Was the signal noise directly related to the injector electrically or was it the result of improper fuel delivery? Quote Link to comment Share on other sites More sharing options...
mchan68 Posted February 13, 2011 Share Posted February 13, 2011 Post #41 of this thread: http://www.thedieselstop.com/forums/f23/2004-f450-no-start-265438/index3.html Quote Link to comment Share on other sites More sharing options...
Bruce Amacker Posted February 13, 2011 Author Share Posted February 13, 2011 Mr. Amacker? Were there ANY other clues that would have led to this diagnosis such as DTC's or PID data? Was the signal noise directly related to the injector electrically or was it the result of improper fuel delivery? I can't answer about the DTCs or PID data. I think the electrical noise from the injector had nothing to do with fuel delivery, it was a shorted coil or something along those lines. Quote Link to comment Share on other sites More sharing options...
joshbuys Posted February 13, 2011 Share Posted February 13, 2011 Was this an intermittent problem or was it consistently duplicable? Quote Link to comment Share on other sites More sharing options...
Bruce Amacker Posted February 13, 2011 Author Share Posted February 13, 2011 Consistently duplicable. Quote Link to comment Share on other sites More sharing options...
Keith Browning Posted February 13, 2011 Share Posted February 13, 2011 Interesting. (scratches his chin) Is there an explanation as to why the starter would be de-enrgized? I swear I have run into that with a truck or two with a bad FICM that was "trying" to start. It sounds like hell! Quote Link to comment Share on other sites More sharing options...
Bruce Amacker Posted February 13, 2011 Author Share Posted February 13, 2011 Is there an explanation as to why the starter would be de-enrgized? No real explanation. When EMI/RFI messes with signals and the PCM, strange things commonly happen. The PCM got pissed off because it was being "spiked" from the injector coil and it made bad decisions. My biggest question is how/why did a shorted(?) injector coil cause irregularities/spikes in the CMPO and CKPO waveforms from the PCM? That's my big quandary. Quote Link to comment Share on other sites More sharing options...
Keith Browning Posted February 13, 2011 Share Posted February 13, 2011 That is why I asked if the concern was electrical or a fueling error. It seems that the later model year trucks the PCM disables the starter when the engine is running, I guess to prevent damage. You know, like turning the key to the start position with the engine running? I always assumed that that what I experienced was related to that strategy in the PCM. I am wondering if that perhaps is what your friend was experiencing whether as a direct or indirect result of the injector concern. Quote Link to comment Share on other sites More sharing options...
Brad Clayton Posted February 14, 2011 Share Posted February 14, 2011 That's an awesome fix, I would have never found that in a million years. Quote Link to comment Share on other sites More sharing options...
joshbuys Posted February 14, 2011 Share Posted February 14, 2011 I've got one out with the VDR on it right now that has an intermittent no start, another tech at the dealer checked it out and changed some parts?!?! Not sure how in depth he got as he is one known for throwing parts, my manager told our advisor to be careful with what diag stuff he's given....anywho....maybe this will be something I can look at on that one. Quote Link to comment Share on other sites More sharing options...
slim Posted February 15, 2011 Share Posted February 15, 2011 I have some scope traces of a truck doing this except mine was just stalling at idle intermittently. It was loosing SYNC and then stalling and I thought I had two different problems but it was the injector causing noise on the CKP & CMP signals. I've been lazy about posting them but since you brought it up I'll get them on here by the end of the week, I need help setting up the scope too, I had a real hard time getting good pictures. Quote Link to comment Share on other sites More sharing options...
hitechmech Posted February 15, 2011 Share Posted February 15, 2011 I've got an injector drawing down the FICM voltages just after tip in, will sit and idle without any problems. No codes present, found FICM dropping off on a road test attempt. Quote Link to comment Share on other sites More sharing options...
Bruce Amacker Posted February 15, 2011 Author Share Posted February 15, 2011 Excellent! I'm thinking this could be a great thread to explain some of those vehicles we could never figure out. If you have scope traces saved, bring them up on your PC screen and push the keyboard button labeled "Print Screen". This used to print the monitor screen in the old DOS days but with all Windows apps it has a new function. It copies what is on your monitor screen into Windows Clipboard which allows you to paste it onto any Word, Powerpoint, Works, or Wordpad document. If you have a picture editing program it may also allow it to be saved as a JPEG or other graphics file to be uploaded onto DTS. I have some scope traces of a truck doing this except mine was just stalling at idle intermittently. It was loosing SYNC and then stalling and I thought I had two different problems but it was the injector causing noise on the CKP & CMP signals. I've been lazy about posting them but since you brought it up I'll get them on here by the end of the week, I need help setting up the scope too, I had a real hard time getting good pictures. Quote Link to comment Share on other sites More sharing options...
Bruce Amacker Posted February 15, 2011 Author Share Posted February 15, 2011 This is also going to be an excellent diagnostic tip in the long run, I think. If we see a regular downward spike in the FICM voltages that corresponds with an injector firing, it would make total sense that one coil is shorted. When you say "drawing down the voltages", can you elaborate? Can you provide a screen capture of this? Feel free to call me at 440-846-3885 if that's quicker. Thanks! I've got an injector drawing down the FICM voltages just after tip in, will sit and idle without any problems. No codes present, found FICM dropping off on a road test attempt. Quote Link to comment Share on other sites More sharing options...
Keith Browning Posted February 15, 2011 Share Posted February 15, 2011 I have a lot of IDS screenshots saved and plan to add a screenshot gallery to the site. If anybody can come up with a screenshot that shows this "noise" that is evident of an injector I am interested in it. Quote Link to comment Share on other sites More sharing options...
Bruce Amacker Posted February 15, 2011 Author Share Posted February 15, 2011 I'll see John Thornton again this weekend in Chicago. I'll ask him more questions about this truck, DTC's, screen captures, and anything else. He's a stickler for documenting things, I hope he took captures of this one. Quote Link to comment Share on other sites More sharing options...
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