Tune/Misfire Question?

[mtuggle86]

I had a plug wire slip off the coil the last pass before driving home from the track. I drove around 1-15 mins while it was off then pulled over to check why the car was running so pour at that time I found the wire found my misfire.

The thing Im wondering is my engine never throw a misfire code or and code at all is that normal? Im sure the knock sensors where tuned to be less sensitive when my car was tuned but should they be tuned down that much?

[Fbomb]

Check the plug in that cylinder. I'm not sure if the knock sensors actually detect misfires or not.

[1BADAIR]

mil light should blink with a misfire like that. back in the day they used to turn the code off but that should not be needed with a 224. i am not sure they do that at all these days

[prorac1]

It all depends on who did the tune. Who tuned the car?

[mtuggle86]

It all depends on who did the tune. Who tuned the car?

S&B did the tune. BTW I checked the plug it still looked good and replaced the wires.

[mtuggle86]

mil light should blink with a misfire like that. back in the day they used to turn the code off but that should not be needed with a 224. i am not sure they do that at all these days

I would imagine he had to of turned it off after 10 mins I cant see any reason why it shouldn't have tripped a misfire code by then. Its not really an issue I was just wondering if it was normal or not.

[ezcruisn71]

The engine knock sensors will only respond to spark detonation. The sensor will decrease spark advance when detonation is observed in the engine. When the engine is misfiring the knock sensor will not detect a misfire.

[DETROITMUSCLE]

I would call Steve and ask but I'm almost 100% sure he turned the codes off, same thing on a buddys car.

[meissen]

The engine knock sensors will only respond to spark detonation. The sensor will decrease spark advance when detonation is observed in the engine. When the engine is misfiring the knock sensor will not detect a misfire.

Yup - knock sensors are for knock, not misfires.

[mtuggle86]

The engine knock sensors will only respond to spark detonation. The sensor will decrease spark advance when detonation is observed in the engine. When the engine is misfiring the knock sensor will not detect a misfire.

Yes your right the crank sensor is used to detect misfires. I figured he set the misfire values back when he did the tune I just wanted to make sure though thanks guys

[prorac1]

My experience with OBD2 tuning is limited. I understand that it is referanced off of the crank sensor, but why would a tuner, tune it out? When tuning my flashable OBD1 stuff, I try to keep as many stock peramiters and saftey measures included as possible to make it user friendly. Is there a reason to desensatize it like that? Thanks Eric L

[Fbomb]

Would tune out misfires because it would detect any misfire, even those caused by a lopey cam. Don't want an MIL to go off every time you idle.

[prorac1]

Ok, thats kinda what I was thinking, but wasnt sure. Thanks Eric L