misfire troubleshooting... my mind is blown

[bmadd2402]

I have a s1 rb25det, which is misfiring at wot, at about 5000 rpm under load. I swaped the wg actuator with a rb20 10psi WG. FMIC, Walbro 255l, 3in turbo back exhaust. I have Datascan, and all the sensors are within spec as far as I can tell, maybe the o2 sensor is a little off. the only thing that I saw is that the injector duty cycle was kinda high. 87.61 at 6650. also the air flow from the MAF was 4.94, also kinda high. I am only running 10 psi, so these shouldn't be that high should they? all the plugs are proerly gapped. I am getting a detonation code from the ecu, and it is pulling 5 degrees of timing at idle. I have great compression, and the plugs dont SHOW any signs of detonation. And then Timing. my cas is fully advanced, and I am still at 20* (with the light). I do have an exhaust leak, if that matters. so it is either maf, cas, fuel, ignition or timing.

Maybe someone could give me a place to start. I need to get the timing sorted out first, so why would the cas be fully advanced and still show 20 degrees of mechanical timing?

Anything I failed to mention just ask.

[foulplay]

Try streching the spring in the coil pacs. My rb20 was not getting good spark on #5. The carbon tip was not making good contact with the spark plug.

[eh?]

The ecu code means there's a problem with the knock sensor circuit. IF that is the case timing will be pulled back across the board. That is probably why you are missfiring and not showing correct base timing.

[bmadd2402]

so you think that is where the problem is? I will test the sensors, anything else anyone?

[bmadd2402]

so a little update: I hooked the car up again to the datascan, and the detonation code is gone, and I have a code 21, ignition system. WTF!! I clear out the codes and the self learn, and do a few revs in neutral. the first was a part throttle, and I got to 6800 and it started missing like the rev limiter kicked in. cheked codes, and nothing. the second time it was part throttle again, till it misfired at 6862 to be exact, then I went wot and it just missed and stuttered even more. again, no codes. so I mash it, trying to go to redline, and it goes right up to 8000. now really, WTF!!! no rev limiter? still no codes. I have tried everything in the manual you can do with the active tests in the ecu. After I cleared the codes and self learn, I did set the timing to 15 and it stayed there.
Modified by bmadd2402 at 5:43 PM 6/27/2007

[bmadd2402]

here is a video of my car misfiring. situation is the same, first I rev it to 2000 to check closed loop, then go paart throttle, it misfires at 6800, then wot to approx 7800. let me know if you see anything!!! http://www.youtube.com/watch?v=aF4MfCsT6PM

[Vkoslak]

Have you checked the gap on your spark plugs? My rb20det misfired right at 5k until i redid my gap. Don't use one of those cheap quarter sized gap tools either. If that isn't it, maybe check your igniter.