Mazdaspeed 3 Stutter
- Thread starter Speedy3
- Start date
Does anyone have a picture of the MS3 EGR valve? I think I found it, but want to make sure.
I've isolated my stutter problem to commanded EGR just prior to turbo boost build up. EGR dumps exhaust gas into the intake to reduce NOx levels in the exhaust. I believe the O2 sensors determine when this should be done. When EGR occurs, potential energy is reduced because of the higher concentration of CO2 and CO, thus reducing the power of the engine. This explains the stuttering I feel. Based on my data logging, when the car has just been started and warmed up and as soon as I hit the gas, the EGR is commanded just prior to the throttle actuator being commanded and the turbo spooling up. Once the car has been run a bit, the probability that an EGR will be commanded during acceleration is significantly reduced; almost completely. I've noticed a slight increase in catalyst temperature at times when the EGR doesn't get commanded during hard accelerations. I was under the impression that EGR is not commanded under heavy loads, but apparently this car does at times.
As far as the cause of this whole phenomenen, I have checked the plugs and cleaned them. Not the problem. The only other thing I can think of is a bad O2 sensor or bad catalytic converter. Damn dealer can't even figure this out which means that I'll have to twist their arms to have the O2 sensor replaced. I turns out that any part replaced under warranty must be sent back to Mazda for analysis, so the dealers are reluctant to do it on new cars under warranty.
I've isolated my stutter problem to commanded EGR just prior to turbo boost build up. EGR dumps exhaust gas into the intake to reduce NOx levels in the exhaust. I believe the O2 sensors determine when this should be done. When EGR occurs, potential energy is reduced because of the higher concentration of CO2 and CO, thus reducing the power of the engine. This explains the stuttering I feel. Based on my data logging, when the car has just been started and warmed up and as soon as I hit the gas, the EGR is commanded just prior to the throttle actuator being commanded and the turbo spooling up. Once the car has been run a bit, the probability that an EGR will be commanded during acceleration is significantly reduced; almost completely. I've noticed a slight increase in catalyst temperature at times when the EGR doesn't get commanded during hard accelerations. I was under the impression that EGR is not commanded under heavy loads, but apparently this car does at times.
As far as the cause of this whole phenomenen, I have checked the plugs and cleaned them. Not the problem. The only other thing I can think of is a bad O2 sensor or bad catalytic converter. Damn dealer can't even figure this out which means that I'll have to twist their arms to have the O2 sensor replaced. I turns out that any part replaced under warranty must be sent back to Mazda for analysis, so the dealers are reluctant to do it on new cars under warranty.
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Problem solved. I replaced the spark plugs today and found two of them with long cracks in the ceramic. The cracks are pitted and filled with carbon depostits. Now the car runs like new again. I have been dealing with the stutter for the past 5000 miles. I wen to the dealer 4 times and they couldn't even take the IC off to access the spark plugs without a CEL. Anyways, if you have a stutter issue in this car, check the plugs.
THIS THREAD IS SOLVED!
THIS THREAD IS SOLVED!
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knowledge007
Banned
nice info haven't had that prob though but good to know...I just broke 7k
CTGrey02 said:
No, they looked exactly like the new plugs I bought. BTW, the dealer reimbersed me for the cost of the plugs and put the whole thing on record and under warranty. A salesman at the Mazda dealer told me that new MS3's are supposably shipped with a new set of plugs in the glove box that are installed during the tech inspection. Not sure if this is true, but interesting considering my experience.
hunterbrandon
Member
- :
- mazdaspeed 3
I only have 3500 miles on my car and i get a bad studder at times too but it dosent matter what rpms and when the studder stops i have A LOT of black smoke coming out of my car. Did you have the same problem?
Speedy3 said:
Glad to hear they noted it, however I think you misunderstood my point. What kind of plugs are in the car stock? Are they copper? Platinums? What brand? NGK? Autolites? I don't mind changing plugs, but they should last more than 2000 miles before you need to replace them due to driveablilty. I normally run NGK copper plugs in my Mustang. They work better than platinum plugs on FI applications.
zoom-zoomhatch
Member
- :
- Cosmic Blue MS3
Didn't you run like lower octane gas for awhile to figure out why the car was running that way, maybe that's why the plugs look so bad. Just offering ideas.
