Diagnosis Wanted
02-17-2009, 04:52 PM
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Diagnosis Wanted
Well I have an 04 AT rx8 with around 55,000 miles, and she has been pretty consistant but has a problem that comes and goes and seems to be getting worse recently, so i'm looking for some help.
There are 3 main symptoms that are troubling me, and i'm convinced that they are all related because they come and go as a group.
First there is a sound like a grinding, or a card in the spokes of a bike tire, that parallels the revving of the engine which will first occur only at higher rpms (4500+), but if it has been doing this for a while during my trip then i can hear this noise from the beginning of my acceleration.
Next I sometimes experience what feels like fuel cut off, I will be sitting at a rest then press on the gas and my acceleration will be very slow even with the pedal to the floor, after a few seconds when i get to around 4000 rpms she usually starts to act normal, but this would be about when the clanking would starts. This "fuel cut off" doesn't only happen from rest, but is when it is most noticable. This leads into the final and most irratiting part of the problem. It has only happened to me on a few occasions but i will come to a complete stop then try to accelerate and my rx8 will bog out and stall (this is an AT). It feels similar to the "fuel cut off" but the rpms will drop below normal idle speed and cause a stall. Following this i have always had trouble starting her up again. It will usually take a few seperate long cranks before it finally catches.
Ill set the scenario for the worst occurance of these problems. - I started my rx8 with ease and drove across town with no problems. I was headed to my bank across town, which is about a mile off a highway outside of town. I came to the stop light at the beginning of the mile stretch and accelerate quickly getting up to 60 mph, and I started to hear the the clanking at high rpms. I pull off to my bank and wait in line (drive through), then when i'm done i pull back onto the highway and trying to accelerate quickly to get up to speed with trafic, but i experience some of the slower acceleration i was describing, and more clanking down the mile stretch. Then I come to the stop light and have to wait for a minute, and when the light turns green and i try to accelerate, she stalls. I hold up traffic while i try to start my car, but the light turns red again before i am able to. Finally she starts and the next green i go. Then another mile or so down the road (of intown driving) at a stop light she bogs as I am waiting (before i started to accelerate, unlike the first time). She died another time that same trip at a 3rd light.
I have only had the problems happen that severely that one time. And later that day she seemed to be running fine.
The noise and the slow acceleration are more common than the stalling, but none of them are a regular occurance.
If anyone thinks they know what may be wrong I would love to hear your imput. I am trying to do some preventative maintenance.
There are 3 main symptoms that are troubling me, and i'm convinced that they are all related because they come and go as a group.
First there is a sound like a grinding, or a card in the spokes of a bike tire, that parallels the revving of the engine which will first occur only at higher rpms (4500+), but if it has been doing this for a while during my trip then i can hear this noise from the beginning of my acceleration.
Next I sometimes experience what feels like fuel cut off, I will be sitting at a rest then press on the gas and my acceleration will be very slow even with the pedal to the floor, after a few seconds when i get to around 4000 rpms she usually starts to act normal, but this would be about when the clanking would starts. This "fuel cut off" doesn't only happen from rest, but is when it is most noticable. This leads into the final and most irratiting part of the problem. It has only happened to me on a few occasions but i will come to a complete stop then try to accelerate and my rx8 will bog out and stall (this is an AT). It feels similar to the "fuel cut off" but the rpms will drop below normal idle speed and cause a stall. Following this i have always had trouble starting her up again. It will usually take a few seperate long cranks before it finally catches.
Ill set the scenario for the worst occurance of these problems. - I started my rx8 with ease and drove across town with no problems. I was headed to my bank across town, which is about a mile off a highway outside of town. I came to the stop light at the beginning of the mile stretch and accelerate quickly getting up to 60 mph, and I started to hear the the clanking at high rpms. I pull off to my bank and wait in line (drive through), then when i'm done i pull back onto the highway and trying to accelerate quickly to get up to speed with trafic, but i experience some of the slower acceleration i was describing, and more clanking down the mile stretch. Then I come to the stop light and have to wait for a minute, and when the light turns green and i try to accelerate, she stalls. I hold up traffic while i try to start my car, but the light turns red again before i am able to. Finally she starts and the next green i go. Then another mile or so down the road (of intown driving) at a stop light she bogs as I am waiting (before i started to accelerate, unlike the first time). She died another time that same trip at a 3rd light.
I have only had the problems happen that severely that one time. And later that day she seemed to be running fine.
The noise and the slow acceleration are more common than the stalling, but none of them are a regular occurance.
If anyone thinks they know what may be wrong I would love to hear your imput. I am trying to do some preventative maintenance.
02-17-2009, 06:08 PM
#2
Certified Mazda Tech
possible compression loss, depending on maintenance history. start off with zoom decarb, fresh plugs, and check coils/wires.
maybe look at cat just because of whats going on in the motor (misfires, unburnt gas etc kill cats)
kevin.
maybe look at cat just because of whats going on in the motor (misfires, unburnt gas etc kill cats)
kevin.
02-17-2009, 06:15 PM
#4
Is this title ok?
Check for a clogged cat and bad coils. You can also test by trying to free rev sitting still; if you have a really bad clogged cat you will feel and see how the car react like fuel cutting out as rpm climb and most likely it will not be able to reach redline without struggling. Take it to the dealer if you had a clogged cat.
If you have bad coils, engine light might flash and you will hear the pop pop... sound like back fire. I had ran thru a couple set of OEM coils in the past. Since you didn't mention anything about replacing the coils, you're coils are due for a check up/replacement at your current mileage.
The other ideas? maybe the torque converter or engine is toasted
If you have bad coils, engine light might flash and you will hear the pop pop... sound like back fire. I had ran thru a couple set of OEM coils in the past. Since you didn't mention anything about replacing the coils, you're coils are due for a check up/replacement at your current mileage.
The other ideas? maybe the torque converter or engine is toasted
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