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Isn't this the same issue you had over a year ago ??...you still didn't get if figured out ??...didn't you say you have a scope ??...did you use it ??....you have either a bad PCM driver or connection at the PCM or wiring issue between the PCM and the coil pack...could be a connection issue at the connector between the 4 and 6 coil packs....the left side is pictured...right side the same....did you look at freeze frame data with a scan tool to see when it's happening ??
This is a very simple circuit with a control wire and the ground for it...remove the connector and front probe the dark green wire...you can just use a DVOM...start the car and you should see the voltage fluctuate between .2 to .3 volts...I think you may have scoped it and seen the 0-4 volt square wave...the brown wire is the reference or computer ground...hook up a test light to B+ and the test light should light up...if you see good voltage and ground you will need to shake down the harness between the coil pack, the connector between 4 and 6 and at the PCM (C2 pin 29)...the reference ground is C2 pin 61....if ALL is good you may need a new PCM...that's all I got !!...I see you have a Picoscope so you might want to back probe the control wire at the PCM and go drive the car and see if that trigger voltage drops out...see if you were driving or at idle when the DTC set in Freeze Frame...if it does the PCM is bad but I'd do a terminal tension test at the PCM....good luck !!!!!!!
This is a very simple circuit with a control wire and the ground for it...remove the connector and front probe the dark green wire...you can just use a DVOM...start the car and you should see the voltage fluctuate between .2 to .3 volts...I think you may have scoped it and seen the 0-4 volt square wave...the brown wire is the reference or computer ground...hook up a test light to B+ and the test light should light up...if you see good voltage and ground you will need to shake down the harness between the coil pack, the connector between 4 and 6 and at the PCM (C2 pin 29)...the reference ground is C2 pin 61....if ALL is good you may need a new PCM...that's all I got !!...I see you have a Picoscope so you might want to back probe the control wire at the PCM and go drive the car and see if that trigger voltage drops out...see if you were driving or at idle when the DTC set in Freeze Frame...if it does the PCM is bad but I'd do a terminal tension test at the PCM....good luck !!!!!!!
These are the parts I need someone to double check for me. It's my first time w a picoscope
There are many YouTube videos on the Picoscope…since the control wire is a 0-4 volt square wave select 10 volts with a 10 second per division scale which will give you a 100 second sample….I see you’re an ASE Tech so this should be a piece of cake for you…someone on one of your previous posts said you’re 2 hours from me so if you don’t feel confident in your diagnosis you can drive out here to the Cape and I can help you with this.
There are many YouTube videos on the Picoscope…since the control wire is a 0-4 volt square wave select 10 volts with a 10 second per division scale which will give you a 100 second sample….I see you’re an ASE Tech so this should be a piece of cake for you…someone on one of your previous posts said you’re 2 hours from me so if you don’t feel confident in your diagnosis you can drive out here to the Cape and I can help you with this.
Many thanks for all your help this morning Rob. I feel like we are pretty certain it's a loose connection at the terminal end of the wiring harness where it plugs into coil pack 4. Ordered the wiring harness from the site you recommended and fingers across that this resolves it once and for all. I haven't felt certain about my diagnostic results on this, but I have confidence in yours. I can see you have many years of experience tackling electrical issues. I'm quite impressed with the array of pigtails harnesses test connectors and diagnostic tools that you have. What an amazing array. Clean setup in the garage and clean approach. Hats off to you man because it's obvious that you have the training that goes along with the tools. I'll keep you posted on here about how it goes with installing the replacement part.
My significant other is making a banana cream pie with those tasty bananas you gave me as well. Thanks again!
Thanks Doug !!…yes, definitely a pin fitment issue and with a 20 year old car replacing the coil pack harnesses would be a great idea…those harnesses get really heat soaked and brittle after all those years so you won’t have to be making anymore trips down this way.
