high idle RPM problem ? help!!!!!
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high idle RPM problem ? help!!!!!
my car has high idle RPM ( about 2500 RPM) when i start the car, it go down after about 5 minutes idling (back to 900 RPM). this happen after i strip the Oxygen sensor on the header due to the header replacement so the guy at the local shop replace it by using the same wire on the sensor and hard wired with some old sensor and install it into the new header. at the same time i changed the spark plugs and wire ( bigger set) myself too.
the problem occurred after that so i'm not sure which one causing the problem, new set of spark plugs and wire or the used Oxygen sensor on the new header.
also i notice a dramatic decrease in the fuel consumption. i think i'm running about 12 to 14 miles per gallon after that. another problem is that my car after driving for about 15 minutes and part or stop at the red light, the idle is start to go up and down,(not smooth idling like it use to be before). and yes the check light engine is on permanently after the old sensor being installed, and flashing sometime when i'm driving on high way at high RPM.
can anyone have any idea what is going on. I personally think that it was the used sensor that cause the problem. or maybe it the old coil with the new wires and spark plug. please help me out guys. thanks alot.
the problem occurred after that so i'm not sure which one causing the problem, new set of spark plugs and wire or the used Oxygen sensor on the new header.
also i notice a dramatic decrease in the fuel consumption. i think i'm running about 12 to 14 miles per gallon after that. another problem is that my car after driving for about 15 minutes and part or stop at the red light, the idle is start to go up and down,(not smooth idling like it use to be before). and yes the check light engine is on permanently after the old sensor being installed, and flashing sometime when i'm driving on high way at high RPM.
can anyone have any idea what is going on. I personally think that it was the used sensor that cause the problem. or maybe it the old coil with the new wires and spark plug. please help me out guys. thanks alot.
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Last edited by lancer; 07-13-2009 at 01:21 PM.
#2
I'm placing my money on the used O2 sensor. The car obviously picked up that the efficiency range of the O2 sensor was not adequate - therefore throwing a CEL light.
Go switch the sensor, reset the NVRAM following procedures, and try that out.
The coils and plugs wouldn't affect the fast idle speed.
Go switch the sensor, reset the NVRAM following procedures, and try that out.
The coils and plugs wouldn't affect the fast idle speed.
#3
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I think you should replace the 02 sensor.
what type of spark plugs? Which wires?
Sounds like your car is misfiring. Are you 100% certain that the plug wires at the spark plugs are properly secured? (they should click / pop when you fasten them all the way)
Are you positive you routed the wires from the coils to the appropriate spark plugs?
I know this seems trivial but it's always best to rule out the simple things first.
Also: you should get the CEL code pulled
Originally Posted by lancer
at the same time i changed the spark plugs and wire ( bigger set) myself too
Originally Posted by lancer
and flashing sometime when i'm driving on high way at high RPM.
Are you positive you routed the wires from the coils to the appropriate spark plugs?
I know this seems trivial but it's always best to rule out the simple things first.
Also: you should get the CEL code pulled
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I think you should replace the 02 sensor.
what type of spark plugs? Which wires?
Sounds like your car is misfiring. Are you 100% certain that the plug wires at the spark plugs are properly secured? (they should click / pop when you fasten them all the way)
Are you positive you routed the wires from the coils to the appropriate spark plugs?
I know this seems trivial but it's always best to rule out the simple things first.
Also: you should get the CEL code pulled
what type of spark plugs? Which wires?
Sounds like your car is misfiring. Are you 100% certain that the plug wires at the spark plugs are properly secured? (they should click / pop when you fasten them all the way)
Are you positive you routed the wires from the coils to the appropriate spark plugs?
I know this seems trivial but it's always best to rule out the simple things first.
Also: you should get the CEL code pulled
I pretty positive that i routed the wires from the coils to the appropriate spark plugs because i changed it one by one.
I will also order the new oxigen sensor today. should i buy a used one (12k) from one of the member on here. he has it for sale for $120 and he said it was working when he took it out of his car. the oxigen sensor for the header are so expensive. any place where they have it for good price?
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#6
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lancer: My personal opinion here...I'd spend the extra money and get a new O2 sensor. It could have been working when he took it off but if it's damanged in transit, you'll be back in this same boat.
I believe Expo1 found the sensors for a pretty good price. Let me see what I can find.
I believe the NVRAM is reset with the 20 brake pedal stomp procedure.
I believe Expo1 found the sensors for a pretty good price. Let me see what I can find.
I believe the NVRAM is reset with the 20 brake pedal stomp procedure.
#7
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Lancer: here's the ECU reset procedure. (see post 3)
https://www.rx8club.com/series-i-tech-garage-22/ecu-clear-reset-27548/
https://www.rx8club.com/series-i-tech-garage-22/ecu-clear-reset-27548/
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Lancer: here's the ECU reset procedure. (see post 3)
https://www.rx8club.com/showthread.php?t=27548
https://www.rx8club.com/showthread.php?t=27548
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#9
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you're welcome Lancer, I'm here to help.
$200 for OEM? Nice.
just as an added bonus, here's the order for the spark plug wires
$200 for OEM? Nice.
just as an added bonus, here's the order for the spark plug wires
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sorry Lancer, only the 1st question is free.
#12
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inconsistant idle can come from a few different sources.
I know I had it with a bad spark plug wire once but I wouldn't doubt that a bad O2 sensor could cause it as well.
the car would be getting bad readings and trying to compensate on false data?
I know I had it with a bad spark plug wire once but I wouldn't doubt that a bad O2 sensor could cause it as well.
the car would be getting bad readings and trying to compensate on false data?
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#14
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unless you're redlining the car like crazy or are doing ALL stop and go, that mpg figure does seem a bit low. I average 17 mpg with mixed driving but I've got a heavy right foot. ![Wink](https://www.rx8club.com/images/smilies/wink.gif)
Let us know how the spark plug inspection goes.
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Let us know how the spark plug inspection goes.
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ok, here is the results. i did check the spark plugs and wire. disconnected and reconnected again and make sure it was tight enough. check the routing too, and it was all corrected. turn the car on, the problem still exist. rough idle, idle go up and down ( not much, about 100 to 300 RPM, but with the custom exhaust that make it noticeable enough when idling). i'm runng 80 miles for .......half tanks of gas now.
for all that, i came to the conclusion to myself that,.....it was all because of the used oxygen sensor. so i hope after changing the sensor, it will be gone.
for all that, i came to the conclusion to myself that,.....it was all because of the used oxygen sensor. so i hope after changing the sensor, it will be gone.
#19
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is it possible something is screwy with your maf? maybe you've got a vacuum leak? I ask because i had similar symptoms when my secondary vacuum inlet was not capped tightly at the throttle body.
all that moving around in there, you may have broken or knocked off one of the hose parts. better check it before you go getting another 02 sensor, i would think.
also, i think you should reset your ecu if you haven't already. that will clear the cel at least temporarily. and it may clear up your problem.
but i don't really know much about anything.
good luck.
all that moving around in there, you may have broken or knocked off one of the hose parts. better check it before you go getting another 02 sensor, i would think.
also, i think you should reset your ecu if you haven't already. that will clear the cel at least temporarily. and it may clear up your problem.
but i don't really know much about anything.
good luck.
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will replace it in the couple days. order for a new one today, and should be here in two days. hope will solve the problems.
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is it possible something is screwy with your maf? maybe you've got a vacuum leak? I ask because i had similar symptoms when my secondary vacuum inlet was not capped tightly at the throttle body.
all that moving around in there, you may have broken or knocked off one of the hose parts. better check it before you go getting another 02 sensor, i would think.
also, i think you should reset your ecu if you haven't already. that will clear the cel at least temporarily. and it may clear up your problem.
but i don't really know much about anything.
good luck.
all that moving around in there, you may have broken or knocked off one of the hose parts. better check it before you go getting another 02 sensor, i would think.
also, i think you should reset your ecu if you haven't already. that will clear the cel at least temporarily. and it may clear up your problem.
but i don't really know much about anything.
good luck.
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#23
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well, just troubleshooting.
you've told us you got a cel. you haven't told us what that cel is. have you read the code?
you also said the cel stays on. after replacing the stripped o2 sensor, did you reset your ecu? you didn't say either way. if so, can i assume the cel came back on after that?
everyone including you has assumed that since you did all this stuff with your 02 sensor and plugs that one or the other is what's causing your problem. And likely that's right. But what if you've presented a false dichotomy?
i have experienced similar symptoms as you. the idle would start out high. i got bad gas mileage. but the issue was not the 02 sensor. It was rather that the secondary vacuum was sucking in unfiltered air.
i am suggesting that in the process of changing the plugs and o2, you've inadvertantly knocked loose one of those lines that sucks air into the intake manifold. And that before you go out and buy something, have a look to see if that's the case.
you've told us you got a cel. you haven't told us what that cel is. have you read the code?
you also said the cel stays on. after replacing the stripped o2 sensor, did you reset your ecu? you didn't say either way. if so, can i assume the cel came back on after that?
everyone including you has assumed that since you did all this stuff with your 02 sensor and plugs that one or the other is what's causing your problem. And likely that's right. But what if you've presented a false dichotomy?
i have experienced similar symptoms as you. the idle would start out high. i got bad gas mileage. but the issue was not the 02 sensor. It was rather that the secondary vacuum was sucking in unfiltered air.
i am suggesting that in the process of changing the plugs and o2, you've inadvertantly knocked loose one of those lines that sucks air into the intake manifold. And that before you go out and buy something, have a look to see if that's the case.
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well, just troubleshooting.
you've told us you got a cel. you haven't told us what that cel is. have you read the code?
you also said the cel stays on. after replacing the stripped o2 sensor, did you reset your ecu? you didn't say either way. if so, can i assume the cel came back on after that?
everyone including you has assumed that since you did all this stuff with your 02 sensor and plugs that one or the other is what's causing your problem. And likely that's right. But what if you've presented a false dichotomy?
i have experienced similar symptoms as you. the idle would start out high. i got bad gas mileage. but the issue was not the 02 sensor. It was rather that the secondary vacuum was sucking in unfiltered air.
i am suggesting that in the process of changing the plugs and o2, you've inadvertantly knocked loose one of those lines that sucks air into the intake manifold. And that before you go out and buy something, have a look to see if that's the case.
you've told us you got a cel. you haven't told us what that cel is. have you read the code?
you also said the cel stays on. after replacing the stripped o2 sensor, did you reset your ecu? you didn't say either way. if so, can i assume the cel came back on after that?
everyone including you has assumed that since you did all this stuff with your 02 sensor and plugs that one or the other is what's causing your problem. And likely that's right. But what if you've presented a false dichotomy?
i have experienced similar symptoms as you. the idle would start out high. i got bad gas mileage. but the issue was not the 02 sensor. It was rather that the secondary vacuum was sucking in unfiltered air.
i am suggesting that in the process of changing the plugs and o2, you've inadvertantly knocked loose one of those lines that sucks air into the intake manifold. And that before you go out and buy something, have a look to see if that's the case.
i did reset my ecu. the cel was gone for awhile and pop up right back. i didn't have a chance to read a code.
thanks for your comments.
#25
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just check all the hoses on your intake downstream from your maf sensor.
the one that gave me trouble is on the underside of the throttle body which is the metal part in front of your intake manifold. if you're standing in front of your engine bay standing in front of it, you'll be looking in the top right corner.
the one that gave me trouble is on the underside of the throttle body which is the metal part in front of your intake manifold. if you're standing in front of your engine bay standing in front of it, you'll be looking in the top right corner.
Last edited by myriadshalaks; 07-14-2009 at 12:18 PM.