P0300 Random Misfire
Jan 22, 2004, 03:42 PM
#16
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CJ:
I'm way out of my element here, but I think your guy may be talking about adjusting the sensitivity of the "scanner" and not really modifying the sensitivity of the ECU to detect a misfire.
If you do find that your guy can adjust the sensitivity for detecting a misfire, that would be some info that could be very helpful to the forum.
Regards,
JS
I'm way out of my element here, but I think your guy may be talking about adjusting the sensitivity of the "scanner" and not really modifying the sensitivity of the ECU to detect a misfire.
If you do find that your guy can adjust the sensitivity for detecting a misfire, that would be some info that could be very helpful to the forum.
Regards,
JS
Jan 22, 2004, 04:03 PM
#17
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causes
How does the computer 'sense' a misfire? Is there a signal coming back from the coil to see if it actually discharged?
I'm sure if the EVO continually 'misfired' the motor would be ... rough? Or...this happens so rarely there is nothing to 'really' worry about?
Tanks,
jcnel.
I'm sure if the EVO continually 'misfired' the motor would be ... rough? Or...this happens so rarely there is nothing to 'really' worry about?
Tanks,
jcnel.
Jan 22, 2004, 07:57 PM
#19
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Why do you have DROVE on your avatar?
Originally posted by SAEVO
What other problems are guys having with there XEDE? I still have mine sitting in box for I guess 3 months now, just waiting for a dyno tune. I would love to hear all the problems with the XEDE so I can get them all ironed out.
thanks
What other problems are guys having with there XEDE? I still have mine sitting in box for I guess 3 months now, just waiting for a dyno tune. I would love to hear all the problems with the XEDE so I can get them all ironed out.
thanks
Jan 23, 2004, 06:14 AM
#21
Re: causes
Originally posted by jcnel_evo8
How does the computer 'sense' a misfire? Is there a signal coming back from the coil to see if it actually discharged?
How does the computer 'sense' a misfire? Is there a signal coming back from the coil to see if it actually discharged?
Toyota had a hard time figuring out how to do this on OBDII manual transmission Supras because road noise was making it back through the transmission and making the crank rotation vary. That is why you could only get an automatic Supra for a year or two while they figured it out. The torque converter shielded the crank from the road noise.
Jan 23, 2004, 07:49 AM
#22
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hmmm....interesting
Thanks Shape,
That's interesting because as a electrical engineer (with some background in signal processing) at 9000 rpm (assumed max. for the EVO), one would get a signal from the crank at 150Hz. (9000 cyclespermin / 60 secpermin). Anyways...a 100 rpm difference would equate to approx. 1.67Hz variation.
My gut feeling is this would be a hard situation to 'test' for in the computer, requiring a lot of engineering development, hence your Supra comment.
One would have to 'hold' the car under load for 'long' enough so that the computer can think it made a good estimate as to if the rpms 'should' be steady, increasing, or decreasing. If the sensitivity were turned up on this algorithm, I'm sure a good front gust of wind could cause a load wild enough for the computer to kick off a misfire error.
Its interesting to note also that some here have actually used the misfire code to check for sparkplug gap problems. Is that just happenchance, or is the misfire algorithm doing what it should be doing?
Hmmm...food for thought.
Later,
jcnel.
That's interesting because as a electrical engineer (with some background in signal processing) at 9000 rpm (assumed max. for the EVO), one would get a signal from the crank at 150Hz. (9000 cyclespermin / 60 secpermin). Anyways...a 100 rpm difference would equate to approx. 1.67Hz variation.
My gut feeling is this would be a hard situation to 'test' for in the computer, requiring a lot of engineering development, hence your Supra comment.
One would have to 'hold' the car under load for 'long' enough so that the computer can think it made a good estimate as to if the rpms 'should' be steady, increasing, or decreasing. If the sensitivity were turned up on this algorithm, I'm sure a good front gust of wind could cause a load wild enough for the computer to kick off a misfire error.
Its interesting to note also that some here have actually used the misfire code to check for sparkplug gap problems. Is that just happenchance, or is the misfire algorithm doing what it should be doing?
Hmmm...food for thought.
Later,
jcnel.
Jan 23, 2004, 07:58 AM
#23
Are you getting the misfire codes at wide open throttle, or when you are just putting around?
With 2G DSMs, the misfire check (I have it turned off), is only performed under certain circumstances. Usually at steady cruise or at idle, etc... But never in open-loop operation.
With 2G DSMs, the misfire check (I have it turned off), is only performed under certain circumstances. Usually at steady cruise or at idle, etc... But never in open-loop operation.
Jan 23, 2004, 08:11 AM
#24
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nope...
If you're referring to me Shape,
I'm not getting misfires yet...but as I 'continue' to modify the EVO I may. To be prepaired as to what the computer is actually doing to determine a misfire, may help me hopefully treat, or ignore a problem.
BTW This is a great board, with really good expertise on hand!
Thanks again,
jcnel.
I'm not getting misfires yet...but as I 'continue' to modify the EVO I may. To be prepaired as to what the computer is actually doing to determine a misfire, may help me hopefully treat, or ignore a problem.
BTW This is a great board, with really good expertise on hand!
Thanks again,
jcnel.
Jan 23, 2004, 09:17 AM
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I just went to the dealership and they confirmed that I was getting the 0300 cel also. They installed some new spark plugs (correctly gapped this time) and wires. It has been about 100 miles since....no cel.
Symptoms= brief but random engine hesitation at various rpm's and load. But it mostly occurred while accelerating moderately in 5th around 75-85mph.
SC~
Symptoms= brief but random engine hesitation at various rpm's and load. But it mostly occurred while accelerating moderately in 5th around 75-85mph.
SC~
Last edited by Secret Chimp; Jan 23, 2004 at 09:24 AM.
Jan 27, 2004, 06:57 PM
#29
Originally posted by Secret Chimp
But it mostly occurred while accelerating moderately in 5th around 75-85mph.
SC~
But it mostly occurred while accelerating moderately in 5th around 75-85mph.
SC~
Jan 28, 2004, 11:44 AM
#30
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Sorry guys. The cel came back on this morning. So it was more likely that the dealerships clearing of the cel from the ECU was the reason it didn't come back on right away. But after the ecu did some 'learning' the cel came back on....and the stuttering....and the annoyance of knowing that I have a 10 month old car with an electronics problem.
SC~
SC~