yellerandahalf
Member
- :
- '03.5 MSP(Yellow!)
Finally got the car to VIR this weekend, went out for the first session in the rain, 10psi, 11.0AFR, 24 degrees of total timing. check here for full details on the car and setup. Car ran really well on track, disgustingly fast. It was raining the first session, so we were moving kinda slow, but we did get up high in 5th gear on the pit strait once. Around 5k rpm, right before I needed to brake for turn one, I noticed a slight bog. Thought I was going crazy, so I kept running. Car ran wonderfully, overtook a GT3 racecar and a new C6 ZO6. Next session out, finally got some clear track in A group, and opened it up in 5th with the race rubber (16" wheels). We hit 5th on the exit of the last corner, and hit 5k rpm in the middle of the strait while passing a porsche. Then the car just BOGGED. got off it, got back on it for more bog, looked down at the AFR gauge to see a 9.2AFR, then noticed that more throttle=less power. Braked for turn one, attempted to accelerate out of 1, noticed the huge bog and large cloud of oil smoke behind me, and trundled around the track back into the paddock.
Apparent Damage:
-oil down back side of block, from what I can see, from about the head gasket area.
-very little compression; sounds like it's running on 2 cylinders. Starts when it's warm, but very difficult.
-Runs without pinging, knocking, or any mechanical noise, just kinda sounds like a tractor.
-I pulled the plugs, to find that the electrode on #2 was broken, and #3 was a little messed up. 1 and 2 were covered in oil, and 3 and 4 looked like they had been running really lean.
-Cylinders 1 and 2 were full of oil. You can actually see your reflection through the spark plug hole.
-sounds like really low compression, won't start when cold, spins really fast, etc. Blows small amounts of oil smoke when running, lots of smoke when you step on the gas.
Ideas:
-Speed limiter?? It's running fuel and spark on Megasquirt. But what if the stock computer somehow triggered the speed limiter? That would be right around 5k rpm in 5th gear, right? What exactly does the speed limited do? Does anyone know?
-I used a non-mazda (topline gasket set) head gasket. The car has been dynoed up to 20psi before (built motor), and held fine. Perhaps the extended pressure of the track was enough to pop the gasket, and allow oil into the cylinders. Then it would burn the oil in 1 and 2, causing the O2 sensor to read really rich, and would cause megasquirt to pull up to 15% fuel, as it's programmed to do. That would cause 1+2 to look like they'd been running lean.
-Busted rings, burned pistons, etc. Not likely, due to lack of mechanical noise.
The car is with Sports and Compacts in Raleigh, NC :gasp:. It's never seen a shop before, but I don't have time to fix it and pass classes at the same time. So they're gonna diagnose and call me soon. I'm really hoping on head gasket.
My part is to figure out what happened to make it run lean like that. Any other ideas?????
Thanks a bunch, let's make this a very open brainstorming session, I promise not to knock anyone's ideas, or call you stupid for suggesting something whacky
-Mateo (zoom zoom poof)
Apparent Damage:
-oil down back side of block, from what I can see, from about the head gasket area.
-very little compression; sounds like it's running on 2 cylinders. Starts when it's warm, but very difficult.
-Runs without pinging, knocking, or any mechanical noise, just kinda sounds like a tractor.
-I pulled the plugs, to find that the electrode on #2 was broken, and #3 was a little messed up. 1 and 2 were covered in oil, and 3 and 4 looked like they had been running really lean.
-Cylinders 1 and 2 were full of oil. You can actually see your reflection through the spark plug hole.
-sounds like really low compression, won't start when cold, spins really fast, etc. Blows small amounts of oil smoke when running, lots of smoke when you step on the gas.
Ideas:
-Speed limiter?? It's running fuel and spark on Megasquirt. But what if the stock computer somehow triggered the speed limiter? That would be right around 5k rpm in 5th gear, right? What exactly does the speed limited do? Does anyone know?
-I used a non-mazda (topline gasket set) head gasket. The car has been dynoed up to 20psi before (built motor), and held fine. Perhaps the extended pressure of the track was enough to pop the gasket, and allow oil into the cylinders. Then it would burn the oil in 1 and 2, causing the O2 sensor to read really rich, and would cause megasquirt to pull up to 15% fuel, as it's programmed to do. That would cause 1+2 to look like they'd been running lean.
-Busted rings, burned pistons, etc. Not likely, due to lack of mechanical noise.
The car is with Sports and Compacts in Raleigh, NC :gasp:. It's never seen a shop before, but I don't have time to fix it and pass classes at the same time. So they're gonna diagnose and call me soon. I'm really hoping on head gasket.
My part is to figure out what happened to make it run lean like that. Any other ideas?????
Thanks a bunch, let's make this a very open brainstorming session, I promise not to knock anyone's ideas, or call you stupid for suggesting something whacky
-Mateo (zoom zoom poof)
