Yes, we definitely need more details describing the events, and video with sound if possible. In at least done cases I have heard it described as less like a misfire and more like a complete shutoff for a few beats then back on. Many people are now familiar with the kind of intermittent “misfire” caused by bad wiring or connectors to the cam or crank sensors, I’m assuming that this is something distinctly different. What’s been described to me sounds more like a complete electrical loss like an intermittent main relay but surely anyone running data would have spotted that by now. I gather that it happens like a light switch, instantly off then instantly back on, which could be all four injectors just stopping then restarting, but NOT something related to fuel pump for example. I hope a lot of people are responding to the survey.
Not too many yet. 37 responses so far but I will probably start reaching out to people to take down notes. I will probably try to start calling people too to get more information from the people who have not answered the survey.
The "VVT Shutoff" is NOT a pipping/popping like the bad cam sensors on the 99s, it is distinctly as if someone turned off the ignition for 3-8 seconds or so. I have many videos that I could show, Id just need to dig them up and edit them together. All the electrical for the car stays on, dash is still on, rpm signal wire is still giving data, but its like the ECU is either not allowing the injectors to pulse or that its not send the signal to spark for 3-8 seconds and then all the sudden it starts firing again.
One theory is that between the advanced timing of the slotted wheels plus the variable valve timing that the timing of the engine gets so far out of wack that the spark can not even ignite the air fuel mixture, but I don't believe that that is what is happening as then I would assume you still get some ignitions and it'd sound more like misfiring, not all together nothing for the 3-8 seconds like what is happening.
People claiming to have the shutoff issue when its misfiring is not the shutoff issue IMO.
Since I believe it is the ECU raining on the parade, to verify that the ECU is actually not sending ignition to the coil packs or the injectors to pulse it was suggested to me by Josh Smith that I hook up an oscilloscope to the Cam Sensor/Crank Sensor, Coil pack and fuel injector wires on a car that has the shutoff and record what's happening during the shutoff period. I have a car that I could do this on and definitely like the idea of doing this.
IMO the ECU is not firing one or both of the coil packs or injectors after it sees that something between the cam and crank sensor is too far out of wack due to us advancing the timing further than stock with the slotted timing wheel. For a lot of the cars that I know that have this issue it goes away after you pull the timing back to stock, base 10 timing. This to me is saying that the ECU shuts stuff down when it doesn't see something it likes when we run the VVTs as 14-16 degrees, which means we are unable to run the cars as we are trying to and or allowed to with the slotted timing wheel. This to me does not make sense to allow us to run. So then a solution to this to me would be we need to not let the VVTs run as much advanced timing, or any more and only run stock timing wheels, but then how do we help them make up for the lost power? Bigger plates? Is that enough? Else we have to allow a ECU that doesn't shut off the car with the current timings that people are running. (This again is granted that is what is happening is that the ECU is shutting things off for the 3-8 seconds).
Tyler Brown
Sneaky Moose Motorsports - Owner
2023 Majors Northern Conference Champion - SM
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2022 Majors Northern Conference Champion - SM
2020 Majors Northern Conference Champion - SM
2019 June Sprints - 1st Place
Design Engineer - Milwaukee Electric Tool
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