#7 - Time to play detective...
Receiving confirmation from FiveO that my injectors tested out healthy was a little disappointing, but, not entirely surprising. This now removes fueling as a possibility for my minor missfire issue between 1900-2400 RPM, 1-2% throttle, and 500-620 hpa.
I went and dug through my logs and tunes and there is nothing indicating a cause, the easiest to see example is below. Dashed lines are the right side value in the graph, solid left side, you can see its a stead state section of 1% rising to 2% throttle, and as RPM falls it goes into misfire mode right at 2570 RPM, inexplicably. I know my fuel pump, filter, and pressure regulator are healthy, I know I’ve no vacuum leaks. My TPS checks out and isn’t sticky.
The cause can be only a handful of things, but, I’m going to start with converting to a Coil on Plug setup. This solves a few issues at once, but, critically it replaces the less than stellar stock coils and removes the prone to failure coil connectors Triumph chose to cheap out on.The weapon of choice will be a COP system from a 2002 Yamaha R1, well, R1s to be more precise. This adds a nice secure weather resistant connection to each coil. It also clears up space under the tank and cleans up the wiring as a whole.
Concurrent with the coil system swap I’ll be swapping from DPR8EA9 plugs to DPR9EA9 plugs and using some old world knowledge, potentially, unlock a handful of horsepower using a couple of tricks. Indexing and sidecutting the strap to expose the spark. If it’s worth a documented 10hp on a 500hp v8, it my give me a couple more, it may yield nothing, but it’s free to try so here we go.
If this doesn’t work to fix the misfire, the options that remain all involve mechanical changes to the motor...
I have been running Torco Accelerator recently, for safety while I try to work through the misfire, unfortunately, Torco Accelerator has a LOT of MMT in it, so it turns your plugs, valves, and exhaust runners a dull red, rust like color. As a result, it makes the plugs almost impossible to read anything useful from.
You can see the color change mid turn on the strap, so ignition timing is good, you can't see any black speckling, another good sign, and the ring face isn't caked in deposits, so it's not insanely rich. What these photos do reveal to me, is confirmation that they're too hot a range of plug. The discoloration on the threads goes too far down them, and the MMT being cooked off the back of the strap are both signs of being too hot.
A lean misfire is just that. Lean. Add more fuel. This problem is found in every R3 I have worked on. If you slowly roll on the throttle bringing rpm up the R3 will likely stumble at 1,900 and again around 2,700. It may be an artifact of the ECU or more likely a characteristic of the intake runner volume, combustion chamber and piston speed combining to change vapor pressure rapidly. This changes the fuel droplet formation and size.
ReplyDeleteI have had to add more fuel in these areas of the map than "should" be needed to keep the engine firing normally. More powerful ignition may light it off but it will remain lean without more fuel. (Give it what it wants, not what you think it should need.)
Don't read too much into your plugs' condition until you run straight, unadulterated fuel.
Indexing ground straps, thinning them and other plug tricks work best on crappy combustion chambers. The R3 has pretty could swirl and tumble so I suspect you will find very little to gain from plug "tricks."
Good to hear about the plug tricks, I am dubious about any gains indexing in a pentroof 4 valve head using dual plugs as well.
ReplyDeleteThe inconsistency of the misfire is why I suspect an abnormal condition. It can’t be tuned out, I’ve tried lots snore fuel and less, it does it intermittently regardless of fueling.