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Discussion Starter · #1 ·
Bone stock minus Cai, catback

, coilovers.Hello everyone. New here. This forum has helped me quite a bit with general info. Finally feel I need to ask for info on an issue.
The car obviously isn't a freaking race car being base auto. But it is considerably different from cold start power to after about 30 minutes of driving. At first the car feels healthy for what it is, pulls good, will even snatch second gear. But after it gets warm, I swear a d15 auto eg would walk all over me. It's like it can't breath, still has the catalytic converter but I have removed it and it's not clogged in any way. I have a code for primary o2 heater circuit. I guess my questions are: will the heater circuit code cause driveability issues such as this? And can the o2 heater wires be backwards? The o2 has been spliced back together by po. Any thoughts are greatly appreciated.
 

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Discussion Starter · #2 ·
Also, when it's warm, the power comes in like segments. Obviously there's the vtec crossover around 4800,5k. But it also feels like a similar increase around 3k and 4k.. with how it feels I swear it should have more than one code but idk. My first rsx and first k series.
 

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If you're throwing a code for your primary sensor, that means it's not working, which means your ECU can't read the a/f ratio. As a result, the ECU will dump fuel into the combustion chamber in order to prevent a lean condition. Both a rich and lean condition will cause a loss of power. If the wires on the sensor were swapped when they were spliced, that may very well be your problem. I would start here.

You won't be able to determine whether or not your cat is clogged by looking at it, it would need to be tested for flow. If it was clogged that bad, you would get a code the cat as well.
Vtec engages at 2200 rpms, the shift in power that you're experiencing at 4700 rpms is the intake valve switching from long to short runners. Any surges in power you noticed aside from this are likely due to the fluctuating a/f ratio at different rpms. The difference in power at cold vs warm temp is normal. Before operating temp, the ecu applies ignition corrections based on the reading from the ECT, so slightly advanced when it's cold. I hope you're not romping on her before she reaches operating temp.
 

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Discussion Starter · #4 ·
Thanks for the reply. Very helpful info.No not at all, it's honestly just good mpg commute car, despite the appearance. My main concern is having to apply the throttle 60% plus just to accelerate on a normal level. That's what I understood on my a/f ratio. I was just unsure if the heater circuit would cause it as well. I thought that if there was only a heater code that the sensor would still be reading. Was maybe thinking the heater code would cause some form of limp or fall back to a default a/f. I'll definitely start with the heater wires this evening, maybe that's my whole issue
 

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exhaust leaks before the O2 sensor can suck air into the system and throw off the A/F ratio readings of the O2 sensor, the exhaust leak can work like a venturi and suck air into exhaust. i am not saying this is happening, I am mentioning it b/c it is an oddity that happens and people miss it throuble shooting on the O2 sensor.
And can the o2 heater wires be backwards? The o2 has been spliced back together by po. Any thoughts are greatly appreciated.
I would start here.
 

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If you're throwing a code for your primary sensor, that means it's not working, which means your ECU can't read the a/f ratio. As a result, the ECU will dump fuel into the combustion chamber in order to prevent a lean condition. Both a rich and lean condition will cause a loss of power. If the wires on the sensor were swapped when they were spliced, that may very well be your problem. I would start here.

You won't be able to determine whether or not your cat is clogged by looking at it, it would need to be tested for flow. If it was clogged that bad, you would get a code the cat as well.
Vtec engages at 2200 rpms, the shift in power that you're experiencing at 4700 rpms is the intake valve switching from long to short runners. Any surges in power you noticed aside from this are likely due to the fluctuating a/f ratio at different rpms. The difference in power at cold vs warm temp is normal. Before operating temp, the ecu applies ignition corrections based on the reading from the ECT, so slightly advanced when it's cold. I hope you're not romping on her before she reaches operating temp.
I hope you're not romping on her before she reaches operating temp.
Indeed. I was told by my tuner (35 year ASE master tech), wait 10 mins of normal driving before laying into the engine. It is night and day in the life of the engine and it's performance reliability. Great advice you gave to the OP brother.


well said sir...

You are right the OEM ECU is designed to operate +/- 10% adjustment on fuel trims.
 

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Indeed. I was told by my tuner (35 year ASE master tech), wait 10 mins of normal driving before laying into the engine. It is night and day in the life of the engine and it's performance reliability. Great advice you gave to the OP brother.


well said sir...

You are right the OEM ECU is designed to operate +/- 10% adjustment on fuel trims.
Same advice I received from my auto teacher. That was just about the only class I paid attention in haha.
 

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Discussion Starter · #14 ·
At that time I was just testing the wheels out. They're on it now. Problem didn't go away, put a test pipe on today and seemed healthier but I haven't got to drive it long. Still have o2s on my list just to make sure its getting all the data it needs. Getting there.. yeah the color was the whole reason we got it, just a bonus low mile and unmolested. Minus paint and springs
 
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