misfire under load; thoughts?
#1
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New motor. Dynotuned by genius Miata Wizards . Road tested on a recent BMW track day. It ran strong;a minimal hot start issue. Ready to race, or so I thought...
A double race weekend, so no test/practice sessions; just (1) qualify and (1) race. Car is rich on start-up and fouls the plugs. Replace with one heat range hotter (NKG 7-->6). Still issues. I just figure that I'd get the car running well in advance of the race and then roll into grid at the 1 min mark (after the "racers start your engine" thing)... no worries. I'd have to start last, but that gives me more slow cars to pass. Fun right?
I get out to qualify and then problem #2 crops up. The car misfires (pop,pop,pop)... like a rev limiter consistently at 6200rpm. I did 2 laps and then came in to change out the plugs/wires... (the local auto store didn't stock coilpacks). As it turned out, this played right into my plan... you see, since I did in fact qualify last place, I didn't have to loose any positions on the grid when I rolled in late!
The first 5-6 laps it was like the Megasquirt rev limiter had been re-set. 6200 rpms at every shift.. pop,pop,pop. I could still pass and work thru traffic but it left me dead slow in the straights. Lap 7 and 8 gave me 6500 rpm. Then, viola! 7400 rpm!! I just had a great time... those back markers never even saw me coming. While I still had an occasional misfire, it was random.
This leaves me a bit reluctant to enter the next race. I just hate showing up unprepared/unreliable; 'hate getting pushed or towed. What are your thoughts? Coilpacks going south? Can a Megasquirt do this? (2004 msm, ms3, moderate boost levels, oem coilpacks (60k miles).New wires, NKG 7,6 plugs tried, oem crank sensor looks to have a .060-.090" gap by eyeball method, lightweight alt and lithium battery recently removed and replaced with oem 80amp charging system and a new oem style lead battery.)
A double race weekend, so no test/practice sessions; just (1) qualify and (1) race. Car is rich on start-up and fouls the plugs. Replace with one heat range hotter (NKG 7-->6). Still issues. I just figure that I'd get the car running well in advance of the race and then roll into grid at the 1 min mark (after the "racers start your engine" thing)... no worries. I'd have to start last, but that gives me more slow cars to pass. Fun right?
I get out to qualify and then problem #2 crops up. The car misfires (pop,pop,pop)... like a rev limiter consistently at 6200rpm. I did 2 laps and then came in to change out the plugs/wires... (the local auto store didn't stock coilpacks). As it turned out, this played right into my plan... you see, since I did in fact qualify last place, I didn't have to loose any positions on the grid when I rolled in late!
The first 5-6 laps it was like the Megasquirt rev limiter had been re-set. 6200 rpms at every shift.. pop,pop,pop. I could still pass and work thru traffic but it left me dead slow in the straights. Lap 7 and 8 gave me 6500 rpm. Then, viola! 7400 rpm!! I just had a great time... those back markers never even saw me coming. While I still had an occasional misfire, it was random.
This leaves me a bit reluctant to enter the next race. I just hate showing up unprepared/unreliable; 'hate getting pushed or towed. What are your thoughts? Coilpacks going south? Can a Megasquirt do this? (2004 msm, ms3, moderate boost levels, oem coilpacks (60k miles).New wires, NKG 7,6 plugs tried, oem crank sensor looks to have a .060-.090" gap by eyeball method, lightweight alt and lithium battery recently removed and replaced with oem 80amp charging system and a new oem style lead battery.)
#8
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I was running lower boost (12-13lbs) with my prior configuration. It ran great for 8+ years. This time I am running 16lbs. I guess a few lbs makes a lot of difference.
Also,' is the LS coil pack the most reliable option? I remember having a LS coilpack failure back in 2001 when I raced a T1 corvette.
Also,' is the LS coil pack the most reliable option? I remember having a LS coilpack failure back in 2001 when I raced a T1 corvette.
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