So I have been have this problem for awhile now, my TJ is an auto but every time I put it into first or second it will throw multiple codes for cylinder misfires. Usually cyclinder 3,4 and 6 and even sometimes all cylinders. I have replaced the crank sensor, cam shaft, coil pack, I’m running champion coppers and I have also changed the TPs. I’ve ruled out just about everything I can think of, really not sure what it is at this point. Any ideas?
Misfiring in first and second gear
JeepsterJake
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So I have been have this problem for awhile now, my TJ is an auto but every time I put it into first or second it will throw multiple codes for cylinder misfires. Usually cyclinder 3,4 and 6 and even sometimes all cylinders. I have replaced the crank sensor, cam shaft, coil pack, I’m running champion coppers and I have also changed the TPs. I’ve ruled out just about everything I can think of, really not sure what it is at this point. Any ideas?
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Sounds like you have changed all sorts of stuff witbout diagnosing the actual problem...
What year is your jeep? Does it do this at idle by simply shifting? If so that pretty much narrows things down to the trans.... shift position sensor maybe.
What year is your jeep? Does it do this at idle by simply shifting? If so that pretty much narrows things down to the trans.... shift position sensor maybe.
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Well that is just stuff I changed over about a one month period when I first started getting cylinder misfires and it fixed the problem so I know it’s none of those. But then I noticed it would misfire in first and second. It’s a 2001 and it only throws a code while I’m driving.
2004 Wrangler TJ, 42RLE auto trans. F/R lockers, 5.38 gears, Warn Winch, Currie 4" Suspension
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Does this problem happen no matter if the engine is cold or warmed up?
And are you sure you're running the right Champion heat range copper plug which is a RC12ECC or 438? One thing about iridium or platinum plugs, they'll fire more easily in sub-optimal engine conditions and for 2-4x as long as conventional plugs do. By the way, platinum and iridium tipped plugs are copper-core as well.
And are you sure you're running the right Champion heat range copper plug which is a RC12ECC or 438? One thing about iridium or platinum plugs, they'll fire more easily in sub-optimal engine conditions and for 2-4x as long as conventional plugs do. By the way, platinum and iridium tipped plugs are copper-core as well.
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It will misfire warm or cold, and yes I’m running the 438’s. Properly gapped and all. Yeah I don’t run any of the platinum or iridium tipped crap, she does not like it at all. I don’t think I have ever heard that, but I’m pretty sure iridium are iridium centered, hence the size difference in electrode vs. coppers. That’s also the reason the other metals besides the copper core will last longer and have lower conductivity. I could be wrong though, just never heard that.
2004 Wrangler TJ, 42RLE auto trans. F/R lockers, 5.38 gears, Warn Winch, Currie 4" Suspension
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Platinum and iridium-tipped plugs that I'm aware of all use copper for their center core, see the bottom illustration as one example.
The ONLY type of platinum plug newer 4.0L engines with the coil pack don't run well are "single-tipped" which means the platinum is only on one side of the gap. Single-tipped platinum plugs that don't run well in the newer 4.0L engine include the Champion 3034 and Autolite AP-985. The single-tipped issue has to do with the "waste spark" design of the newer 4.0L that fires each plug twice as often, and in opposite polarity directions... which is why the platinum or iridium coating needs to be on both sides of the gap, not just one. So single-tipped platinum spark plugs, as some auto parts stores will sell you out of ignorance, will cause misfires on newer ignition systems like yours Double-tipped platinum plugs like the APP-985 from Autolite or the 7034 from Champion will run perfectly without misfires.
With the proper double-tipped platinum design where the platinum coating is on both sides of the spark gap, it works beautifully and lasts 3-4X as long. Champion's 7034 and Autolite's APP-985 are double-tipped designs which is designed for waste-spark ignition systems like yours is. Or Iridium-tipped designs like Autolite's XP-985 which is what I run. Autolite looked at their iridium-tipped plugs at 200k miles under an electron scanning microscope and they found absolutely no wear, pitting, etc. They're not quite sure how long they'll last but it's at least 200k miles. I know the people who did that test, it surprised everyone. The iridium coating works so well that Autolite now gives a lifetime warranty on its iridium-tipped plugs.
So when we talk about platinum or iridium tipped plugs, we're only talking about a very thin coating on the electrode tip itself, not the core which remains as a copper core. It serves solely to protect the electrodes from erosion.
And don't worry about the slight added resistance which for ignition systems is a non-issue. In fact, resistance is actually added at extra cost to ignition wiring to reduce static/spark noise. All spark plugs used in automotive ignition systems are resistor-style where resistance is actually added, again at extra cost.
Like lightening has no problem arcing through the air, neither does spark voltage which is typically over 20,000 volts have any problem passing through the platinum or iridium coating. That high spark voltage doesn't even notice the microscopically thin layer iridium or platinum coating, it passes through it like it isn't even there.
We're talking over 20,000 spark voltage at a very low current where a platinum or iridium coating has zero reduction of the spark intensity. Ohm's Law (E=IR) shows why, and it has to do with the extremely low current that the spark requires. With very little current flow, there is very little voltage loss across the wiring and spark plugs. So when there is more voltage provided to the spark plug than is required to reliably ignite the air-fuel mixture, it's a complete non-issue.
P.S. That "necked down" mentioned below allows the spark plug to require less voltage to fire reliably, it makes the spark more reliable and more able to fire in conditions that could cause misfires.
I completed several industry conducted ignition system and spark plug technology courses a couple years ago so this is a subject I'm pretty up on.
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Ok so you aren't manually shifting the trans to low or 2nd to cause the misfire correct?
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Haha well okay thank you for the info, but besides the fact I still need to figure out this multiple misfire problem.
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It will throw the code when I put my jeep into 2nd and 1st from 3rd. It’s an automatic.
2004 Wrangler TJ, 42RLE auto trans. F/R lockers, 5.38 gears, Warn Winch, Currie 4" Suspension
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About the only thing that now comes to mind on your misfires is a bad upstream O2 sensor or two, or one or both of the two pre-catalytic converters have gone bad.
I bought my present '04 TJ used with some misfires happening the PO didn't tell me about, then he later admitted he tried replacing the O2 sensors to fix it which didn't cure them.
What ended up curing the misfires was replacing both pre-catalytic converters. What forced the issue was when one of the two pre-cats, likely the one causing the misfires, suddenly disintegrated internally and dumped its insides downstream into the main catalytic converter and plugged it.
No misfires since replacing all my cats several years ago.
Since your misfires occur whether your engine is cold or warm, I'd lean toward a bad pre-cat. Bad O2 sensors only cause problems after the engine starts getting warmed up.
I just wanted to make sure in my previous post that your misfires weren't being caused by something simple and inexpensive, the wrong spark plugs which it now doesn't seem to be.
I bought my present '04 TJ used with some misfires happening the PO didn't tell me about, then he later admitted he tried replacing the O2 sensors to fix it which didn't cure them.
What ended up curing the misfires was replacing both pre-catalytic converters. What forced the issue was when one of the two pre-cats, likely the one causing the misfires, suddenly disintegrated internally and dumped its insides downstream into the main catalytic converter and plugged it.
No misfires since replacing all my cats several years ago.
Since your misfires occur whether your engine is cold or warm, I'd lean toward a bad pre-cat. Bad O2 sensors only cause problems after the engine starts getting warmed up.
I just wanted to make sure in my previous post that your misfires weren't being caused by something simple and inexpensive, the wrong spark plugs which it now doesn't seem to be.
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I understand that it's an automatic but I'm trying to determine is whether it has anything to do with the transmission at all... You keep focusing on first and second gear so I'm trying to narrow down if that has anything to do with it...
Currently my best guess is that it has absolutely nothing to do with first or second gear and everything to do with engine RPM.... that it might possibly still do it in 3rd gear if you had the RPMs high enough with the same throttle input..... ie high speed or low range
Currently my best guess is that it has absolutely nothing to do with first or second gear and everything to do with engine RPM.... that it might possibly still do it in 3rd gear if you had the RPMs high enough with the same throttle input..... ie high speed or low range
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