ive heard of shiver me timbers but this?
LOL !!! and welcome back.
my guess is that cyclical action, is the ECU trying hard to correct this.
Keep in mind, a scan tool can show many errors, some of which newer glow the CEL. at all. and in Canada less. (on some kicks, like 25 things) never fail to scan, at the first odd engine symptoms..
it's just misfire. the causes are many.
misfire is bad spark , bad fueling or bad engine compression. the 3 classics.
is spark timing right?
is the rotor not on the wrong way? one way , can allow the rotor to cross fire cylinders, the the other (1 of3) wrong ways kills all spark.
injector leaks or clogs.?
(most oxy sensors are past their prime at 100k miles, for many reasons. and are cheap parts, like $50 or $20 for generic)
O2 sensor slammed lean (exhaust leaks near it) causing ECU to slam fuel mix rich and it rich misfires. (super easy to see even with a $9 scan tool) you see say pending p0300s, and dead 02 and LTFT way off.
the O2 , is the driving force to the LTFT. (if the 02 lies, so does LTFT) The key word there is trim, what if the silly thing trims in the wrong direction, I'm all over that bad act...
weak compression on one cylinder can make it misfire. the ECU injects for fully good cylinders (a shared 02 is reason). (a weak cylinder goes rich and misfires.)
a leaking injector causes misfire, and will make them all misfire due to Oxygen passing fro the intake (unused) past a dead cylinder to the 02 sensor, causing it to lie like a dog. (false lean) (the ECU never knows fuel mix only OXYGEN)
IF the, Intake air leaks real bad, can cause lean misfire, but not at 3000 rpm. (the leak become tiny, in the total huge flow of air....)
the AC on ,just tells the ECU to go to fast idle mode , nothing more.
Your engine is misfiring at many points in the RPM load curve.
Id use only idle misfire in my ATTACK, because why?, it's easy, i'm not moving, it does it over and over and i can fix it. finding under load misfire is vastly more hard and complex. (and some risk , use 2 persons to do moving checks)
but at idle, the 02 must work right, if it don't?, it will misfire, especially if the 02 is fibbing, (it can help or hinder. that is its deal)
on my 96/97 the O2 come on line fast in about 15 seconds on a warm spring day.
keep in mind the 02 drops out , accelerating and going up hills. (load) So that is why it misfires only with static RPM and no loads. It's because the 02 is ACTIVE. At idle and light flat cruising..
my scan tool has this.
http://www.fixkick.com/ECU/Authority/A_F..._scan.html
oxygen sensor closed loop status (CL or Active)
see that. that is the 1st thing i do.
see me do it here (link above), step by step, my checks.
the ECu tries hard to get the engine at STOIC (no smog) and trusts the sensors. If the sensors fib, the ECU will in fact mess up injection or even make it worse. (02 sensors love to do that worse thing)
you see it misfire, that is its way of crying for help. it will get worse.
key causes, advanced.
1: exhaust crack near the front 02 sensor.
2: the exh. donut gasket bad, (more are by now, shunk or pound to death flat and leaks)
3: #4 exhaust tube cracked (02 will be dead, (even if good) for leaks.
![[Image: 96-num4-cracked.JPG]](http://www.fixkick.com/look/96-num4-cracked.JPG)
amazing it not enough to make front 02 go nuts yet but will soon.
i 'd get this. the CALmini,
only if cracked any only if it effects my 02, as it surely will soon.
http://www.fixkick.com/buy-parts.html#calmini
LOL !!! and welcome back.
my guess is that cyclical action, is the ECU trying hard to correct this.
Keep in mind, a scan tool can show many errors, some of which newer glow the CEL. at all. and in Canada less. (on some kicks, like 25 things) never fail to scan, at the first odd engine symptoms..
it's just misfire. the causes are many.
misfire is bad spark , bad fueling or bad engine compression. the 3 classics.
is spark timing right?
is the rotor not on the wrong way? one way , can allow the rotor to cross fire cylinders, the the other (1 of3) wrong ways kills all spark.
injector leaks or clogs.?
(most oxy sensors are past their prime at 100k miles, for many reasons. and are cheap parts, like $50 or $20 for generic)
O2 sensor slammed lean (exhaust leaks near it) causing ECU to slam fuel mix rich and it rich misfires. (super easy to see even with a $9 scan tool) you see say pending p0300s, and dead 02 and LTFT way off.
the O2 , is the driving force to the LTFT. (if the 02 lies, so does LTFT) The key word there is trim, what if the silly thing trims in the wrong direction, I'm all over that bad act...
weak compression on one cylinder can make it misfire. the ECU injects for fully good cylinders (a shared 02 is reason). (a weak cylinder goes rich and misfires.)
a leaking injector causes misfire, and will make them all misfire due to Oxygen passing fro the intake (unused) past a dead cylinder to the 02 sensor, causing it to lie like a dog. (false lean) (the ECU never knows fuel mix only OXYGEN)
IF the, Intake air leaks real bad, can cause lean misfire, but not at 3000 rpm. (the leak become tiny, in the total huge flow of air....)
the AC on ,just tells the ECU to go to fast idle mode , nothing more.
Your engine is misfiring at many points in the RPM load curve.
Id use only idle misfire in my ATTACK, because why?, it's easy, i'm not moving, it does it over and over and i can fix it. finding under load misfire is vastly more hard and complex. (and some risk , use 2 persons to do moving checks)
but at idle, the 02 must work right, if it don't?, it will misfire, especially if the 02 is fibbing, (it can help or hinder. that is its deal)
on my 96/97 the O2 come on line fast in about 15 seconds on a warm spring day.
keep in mind the 02 drops out , accelerating and going up hills. (load) So that is why it misfires only with static RPM and no loads. It's because the 02 is ACTIVE. At idle and light flat cruising..
my scan tool has this.
http://www.fixkick.com/ECU/Authority/A_F..._scan.html
oxygen sensor closed loop status (CL or Active)
see that. that is the 1st thing i do.
see me do it here (link above), step by step, my checks.
the ECu tries hard to get the engine at STOIC (no smog) and trusts the sensors. If the sensors fib, the ECU will in fact mess up injection or even make it worse. (02 sensors love to do that worse thing)
you see it misfire, that is its way of crying for help. it will get worse.
key causes, advanced.
1: exhaust crack near the front 02 sensor.
2: the exh. donut gasket bad, (more are by now, shunk or pound to death flat and leaks)
3: #4 exhaust tube cracked (02 will be dead, (even if good) for leaks.
amazing it not enough to make front 02 go nuts yet but will soon.
i 'd get this. the CALmini,
only if cracked any only if it effects my 02, as it surely will soon.
http://www.fixkick.com/buy-parts.html#calmini
http://www.fixkick.com