Who has the random misfire problem?

LightningGSX · 05-31-2005

Whos got it? I have an idea that should fix it.

StealthGST · 05-31-2005

you mean me? Although mine's just fuel problems heh, hoping a good fuel regulator and a tune will fix it

blageo23 · 05-31-2005

I got it! I just swaped a 6bolt in and it sucks. whats your idea?
Mike

LightningGSX · 05-31-2005

Quote:

Originally Posted by StealthGST

you mean me? Although mine's just fuel problems heh, hoping a good fuel regulator and a tune will fix it

You didn't have the misfire code when I checked last.

**scheides** · 05-31-2005

I don't think I do, right now I'm throwing CEL due to all my EGR stuff missing.

LightningGSX · 05-31-2005

Quote:

Originally Posted by blageo23

I got it! I just swaped a 6bolt in and it sucks. whats your idea?
Mike

Smooth out the crank angle pulses.Like average them out over say 4 pulses.The pulse edges will still be the same, so injectors and timing will trigger as its supposed too, but the ECU won't think there is RPM fluctuations anymore.I'm about 99% sure it will work.

**1ViciousGSX** · 06-01-2005

Quote:

Originally Posted by LightningGSX

Smooth out the crank angle pulses.Like average them out over say 4 pulses.The pulse edges will still be the same, so injectors and timing will trigger as its supposed too, but the ECU won't think there is RPM fluctuations anymore.I'm about 99% sure it will work.

WTF?

TalonFiero · 06-01-2005

I have RM if I unselect the check in DSMLink.

Jim

LightningGSX · 06-01-2005

Quote:

Originally Posted by 1ViciousGSX

WTF?

The ECU times the crank angle pulsewidths for RM checking.If the times change drastically, from pulse to pulse, the misfire code gets set.The injection and ignition get triggered on the falling edge of the pulse(when it goes from on to off).I'm not sure what the actual threshold is, but for example, lets say one pulse is 50 mS, and the next is 40 mS.Since normal accel/deccel can't change that quickly, the ECU interprets that as misfire.Now if you were to smooth out the pulses, like not let them change more than 2-3 mS per pulse/per 4 pulses, by extending the beginning of the pulse so the falling edge stays where its supposed to be, misfire code would be gone and nothing else would be effected.

LightningGSX · 06-01-2005

For the fixing part.I have these tiny self contained data loggers that I built a few years ago.First, I log CA signal fluctuation on a vehicle where the CA sensor is on the crank(my 2g).Second I log CA signal fluctuation on a vehicle where the CA sensor is cam mounted(1g or 2g w/1g motor).From the 2, I can figure out the threshold.After that, the actual smoothing part is real easy, I've thought up about 5 ways to do it, most cheap and reliable.

EclipseGST · 06-01-2005

How do you do it?

blageo23 · 06-01-2005

If its simple and you dont have to do much and its cheap. I am down. What does my car need for this to be done? just the code? Do I need datalogger or anything?
Mike

**1ViciousGSX** · 06-01-2005

Quote:

Originally Posted by LightningGSX

The ECU times the crank angle pulsewidths for RM checking.If the times change drastically, from pulse to pulse, the misfire code gets set.The injection and ignition get triggered on the falling edge of the pulse(when it goes from on to off).I'm not sure what the actual threshold is, but for example, lets say one pulse is 50 mS, and the next is 40 mS.Since normal accel/deccel can't change that quickly, the ECU interprets that as misfire.Now if you were to smooth out the pulses, like not let them change more than 2-3 mS per pulse/per 4 pulses, by extending the beginning of the pulse so the falling edge stays where its supposed to be, misfire code would be gone and nothing else would be effected.

I know what causes the code to set, I never heard of smoothing the cas signal.

LightningGSX · 06-01-2005

Quote:

Originally Posted by 1ViciousGSX

I know what causes the code to set, I never heard of smoothing the cas signal.

Probably because no one has ever thought of it.

Scratch that anyway, I figured out a much better way of taking care of the problem, and EGR/O2/Evap codes too.Details when I know if it works.

blageo23 · 06-01-2005

How long you thinking? cuz that would be sweet. My car would be perfect if it didnt have the Random misfire and O2 codes. Let me/us know asap.