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I saw a few other threads with P0172, but the original posters never came back and said what fixed their issues. So, this is more for anyone that comes across this for later, as I'll keep it updated. Note that these codes are pending, and my car never had a CEL.
Symptoms: Power loss on the highway, trouble idling, and trouble returning to idle.
Measurements: When in cruise, car lost all power momentarily, then retuned. During this power loss, primary O2 read 11:1. A quick run to red line shows no symptoms, pulls fine with no issues in 2nd, 3rd with normal afrs in the rich range from the stock tune. This also will temporarily fix the power loss , and reading primary O2, it'll run mid 14s ...the...drop to 11 and instant power loss, all while in cruise.
At idle, it will struggle to maintain. When it idles fine, primary O2 reads upper 14s, then it'll instantly drop to 11 and the idle will get chunky. Note that smell from exhaust at this time does not smell rich.
Cat temps are normal, 1600 on a 75mph cruise.
Car: 2005 GT, 150k miles with 51k on a reman. Ls2 coils really the only engine mod. Plugs have less than 5k miles. Cat recently checked and looked fine.
Suspect: Primary O2 failure.
I have an extra OE one, will replace and update here.
Troubleshooting P2097, it asks if P0172 is present. If yes, troubleshoot that, which I was doing anyway.
So, I put in a new front O2, and it ran fine. Drove around a bit, trims were all jacked up and it idles terribly, but it got better. Highway cruise was hovering around 15:1..little lean. So, instead of waiting for it to sort itself, I reset the ecu and now everything is back to normal.
I think think problem solved. Now, hope people find this thread when they search!
I just started getting hesitation between 3500-4500 rpm and a uneven idle. Then I got 2 codes, same as you.
Did the new primary o2 fix this for you?
Any other probable causes?
Bhr coil.kit, aem intake, cooling relay mod. I will monitor cat temps but high rpm feels good like before. Reman engine with 6k. Cat temps hover around 1600F on 90F day.
Did another run and got high rpm misfire, then ok again.
miles
Yep, primary O2 fixed it. Looks like you have Torque, so look at the live AFRs when it starts having a problem. If the signal is clipped high or low, then its most likely the primary O2.
That would be upstream or downstream o2 sensor, as that's how I see they are listed for the rx8?
You say look at afr(am I looking for rich or lean), but what about o2 voltage, or short term fuel trim?
Originally Posted by MikeTyson8MyKids
Yep, primary O2 fixed it. Looks like you have Torque, so look at the live AFRs when it starts having a problem. If the signal is clipped high or low, then its most likely the primary O2.
That would be upstream or downstream o2 sensor, as that's how I see they are listed for the rx8?
You say look at afr(am I looking for rich or lean), but what about o2 voltage, or short term fuel trim?
I can't say for certain how your trims should look, but watch the upstream O2 AFR live. When you start experiencing your symptoms, see what it reads. Looks like you've got a lot of other errors in there too?
Cooling fan error is not a problem,only because I have the cooling relay modification.
Originally Posted by MikeTyson8MyKids
I can't say for certain how your trims should look, but watch the upstream O2 AFR live. When you start experiencing your symptoms, see what it reads. Looks like you've got a lot of other errors in there too?
I saw a few other threads with P0172, but the original posters never came back and said what fixed their issues. So, this is more for anyone that comes across this for later, as I'll keep it updated. Note that these codes are pending, and my car never had a CEL.
Symptoms: Power loss on the highway, trouble idling, and trouble returning to idle.
Measurements: When in cruise, car lost all power momentarily, then retuned. During this power loss, primary O2 read 11:1. A quick run to red line shows no symptoms, pulls fine with no issues in 2nd, 3rd with normal afrs in the rich range from the stock tune. This also will temporarily fix the power loss , and reading primary O2, it'll run mid 14s ...the...drop to 11 and instant power loss, all while in cruise.
At idle, it will struggle to maintain. When it idles fine, primary O2 reads upper 14s, then it'll instantly drop to 11 and the idle will get chunky. Note that smell from exhaust at this time does not smell rich.
Cat temps are normal, 1600 on a 75mph cruise.
Car: 2005 GT, 150k miles with 51k on a reman. Ls2 coils really the only engine mod. Plugs have less than 5k miles. Cat recently checked and looked fine.
Suspect: Primary O2 failure.
I have an extra OE one, will replace and update here.
If anyone else would like to add, please do!
So was it the upstream oxygen sensor? I'm having the exact same problem. Appreciate it
Yep, primary O2 fixed it. Looks like you have Torque, so look at the live AFRs when it starts having a problem. If the signal is clipped high or low, then its most likely the primary O2.
Originally Posted by SM RX-8
So was it the upstream oxygen sensor? I'm having the exact same problem. Appreciate it
08-31-2015, 06:20 AM
