4.7 intermittent mis fire user load during light throttle no codes
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Disconnecting the sensor WILL set a code, but, aside from that, no other issues. The PCM won't have feedback from the sensor to adjust mixture ratio, so, it will just run off of tables programmed into the PCM, which tend to be a tad rich.....
O2 sensors have a variety of failure modes that won't set a code. Mainly because the PCM doesn't know that it is getting bad data..... It has nothing to compare it to. A lazy O2, or one that isn't quite accurate, can give you an overly rich, or lean... mixture, which can lead to misfires. At larger throttle openings, the PCM ignores the O2 sensor anyway..... thus, the problem goes away if you step on the gas harder. (if the problem IS related to the O2 sensor.) The fact that the front sensor is spliced into the wiring harness, is NOT real confidence inspiring.
O2 sensors have a variety of failure modes that won't set a code. Mainly because the PCM doesn't know that it is getting bad data..... It has nothing to compare it to. A lazy O2, or one that isn't quite accurate, can give you an overly rich, or lean... mixture, which can lead to misfires. At larger throttle openings, the PCM ignores the O2 sensor anyway..... thus, the problem goes away if you step on the gas harder. (if the problem IS related to the O2 sensor.) The fact that the front sensor is spliced into the wiring harness, is NOT real confidence inspiring.
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From: Clayton MI
Rear O2 just monitors the cat, so, if you aren't getting any codes relating to that, don't worry about it for now.... Likely not a contributor to the problem. Still, I would unplug the front sensor, and go for a drive. See what happens. It's cheap, it's easy, it's free.
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yes your correct I’m the event it’s not the O2 sensor and problem remains what would be next thing to look at considering how quiet and smooth it’s running?
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Given the intermittent nature..... I am thinkin' it is highly likely to be an electrical problem somewhere. Who knows, maybe a crappy connection on that spliced in sensor has enough of an effect to cause it??? I don't *think* the rear O2 has much, if any, control over fueling, but, I've been wrong before. I know, shocker, right? Not sure I would be all that concerned about it, if I didn't have a warm place to work though.
I know, shocker, right? Not sure I would be all that concerned about it, if I didn't have a warm place to work though.
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Given the intermittent nature..... I am thinkin' it is highly likely to be an electrical problem somewhere. Who knows, maybe a crappy connection on that spliced in sensor has enough of an effect to cause it??? I don't *think* the rear O2 has much, if any, control over fueling, but, I've been wrong before. I know, shocker, right? Not sure I would be all that concerned about it, if I didn't have a warm place to work though.
I know, shocker, right? Not sure I would be all that concerned about it, if I didn't have a warm place to work though.
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Given the intermittent nature..... I am thinkin' it is highly likely to be an electrical problem somewhere. Who knows, maybe a crappy connection on that spliced in sensor has enough of an effect to cause it??? I don't *think* the rear O2 has much, if any, control over fueling, but, I've been wrong before. I know, shocker, right? Not sure I would be all that concerned about it, if I didn't have a warm place to work though.
I know, shocker, right? Not sure I would be all that concerned about it, if I didn't have a warm place to work though. So I disconnected the front O2 sensor and it's definitely driving smoother. I can't say it's 100%. It still sounds and feels a little funny. Very light throttle in the bottom of fourth gear but it's not banging and sputtering intermittently like it was before
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the fact it’s not throwing a code is what’s really a mind **** though it happens if the rear o2 wouldn't cause that to happen. And my engine is running quietly I’m at a loss ! I’m going to disconnect that from o2 sensor . I know there is a pin hole exhaust leak on a weld near the cat but that wouldn’t cause a misfire and lack of power guess it’s time to pull the sensor then if that don’t do it pull the remaining coils
Last edited by apjcustoms; Jan 30, 2025 at 03:28 PM.
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From: Clayton MI
These trucks really don't like aftermarket sensors.... Yeah, I know, the mopar fellers are NOT cheap.... but, they actually WORK right. Might be tempted just to score some from a nearby wrecking yard, if there is one.... install those, reset the computer, and see what you get.
Denso or NTK O2 sensor ONLY please. Don't bother with Bosch.....
Denso or NTK O2 sensor ONLY please. Don't bother with Bosch.....
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These trucks really don't like aftermarket sensors.... Yeah, I know, the mopar fellers are NOT cheap.... but, they actually WORK right. Might be tempted just to score some from a nearby wrecking yard, if there is one.... install those, reset the computer, and see what you get.
Denso or NTK O2 sensor ONLY please. Don't bother with Bosch.....
Denso or NTK O2 sensor ONLY please. Don't bother with Bosch.....