Choppy Power Delivery at ~4000rpm
05-18-2006, 07:27 PM
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Choppy Power Delivery at ~4000rpm
Hi guys, I don't post much but I thought this was worth a mention. I'm having some problems with the car that are explained in the little report I am going to give the Service guys (better than trying to explain it verbally):
I do not wish to diminish the respect and credibility of the RX-8 or my dealer. Stuff happens 
Though it was kinda funny leaving a Commodore literally in the smoke.
My first thought is there's something wrong with the SDAIS (hopefully?). If you guys have any comments or ideas they would be appreciated.
Cheers,
PS. I should mention that it was suggested that I replace the O2 sensor after the stone damage (the part is $2000 or so), but that it would not cause problems if I did not.
35000kms
Major Issues
• Severely choppy power delivery at around ~4000RPM (feels like driving over a few small smooth bumps)
o Seems to rev freely after 4000RPM, though I have not redlined the car
• Running extremely rich
o White residue around exhaust tips (but seems to be burning oil normally)
o Strong petrol smell when idling and just after stopping
• Large cloud of white smoke left behind occasionally when accelerating from stand-still
Notes
• Engine is idling smoothly and running smoothly apart from at ~4000RPM
• No Check Engine light (WDC may not diagnose any problems)
• Oil checked and topped up regularly
• Has only ever run on 98RON fuel (BP Ultimate)
• Minor stone damage to catalytic-converter. I don’t believe this is to blame for the problems as there is usually a CEL if it is not running efficiently
• Car is well maintained and serviced every 5000kms
The Power dip is most noticeable when changing into 2nd or 3rd at a fairly low rpm (3000) then revving up to 4000 from ~2000 with over 50% throttle.
At the last service I mentioned the dip in power at 4000RPM. Only the ECU was checked for software upgrades. This definitely did not fix the problem; it seems to have escalated since then.
Major Issues
• Severely choppy power delivery at around ~4000RPM (feels like driving over a few small smooth bumps)
o Seems to rev freely after 4000RPM, though I have not redlined the car
• Running extremely rich
o White residue around exhaust tips (but seems to be burning oil normally)
o Strong petrol smell when idling and just after stopping
• Large cloud of white smoke left behind occasionally when accelerating from stand-still
Notes
• Engine is idling smoothly and running smoothly apart from at ~4000RPM
• No Check Engine light (WDC may not diagnose any problems)
• Oil checked and topped up regularly
• Has only ever run on 98RON fuel (BP Ultimate)
• Minor stone damage to catalytic-converter. I don’t believe this is to blame for the problems as there is usually a CEL if it is not running efficiently
• Car is well maintained and serviced every 5000kms
The Power dip is most noticeable when changing into 2nd or 3rd at a fairly low rpm (3000) then revving up to 4000 from ~2000 with over 50% throttle.
At the last service I mentioned the dip in power at 4000RPM. Only the ECU was checked for software upgrades. This definitely did not fix the problem; it seems to have escalated since then.
Though it was kinda funny leaving a Commodore literally in the smoke.My first thought is there's something wrong with the SDAIS (hopefully?). If you guys have any comments or ideas they would be appreciated.
Cheers,
PS. I should mention that it was suggested that I replace the O2 sensor after the stone damage (the part is $2000 or so), but that it would not cause problems if I did not.
Last edited by Evergrey; 05-18-2006 at 07:33 PM.
05-18-2006, 07:39 PM
#2
not sure I'm reading this correctly, but at 4k rpm the car doesn't make a lot of power. you might just be bogging it. Do you have a friend or someone nearby that you can compare cars with?
05-18-2006, 07:46 PM
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It is a definite dip in power, imagine releasing the throttle a little bit then back on it.
Sometimes it feels like going over a few bumps, if you can imagine pressing and releasing the accelerator quickly a few times.
Edit: I don't have any other car to compare, though I can compare when I would smile every time I got in the car, to now, knowing something is not quite right every time get in the car.
Sometimes it feels like going over a few bumps, if you can imagine pressing and releasing the accelerator quickly a few times.
Edit: I don't have any other car to compare, though I can compare when I would smile every time I got in the car, to now, knowing something is not quite right every time get in the car.
Last edited by Evergrey; 05-18-2006 at 07:54 PM.
05-18-2006, 08:35 PM
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sounds like an electrical thing.
I have had something similar when using cruise control. Felt like sudden lifting and reapplication of throttle, giving a surging effect. So maybe the computer is getting confused. Why don't you try it with traction control on full off?
I have had something similar when using cruise control. Felt like sudden lifting and reapplication of throttle, giving a surging effect. So maybe the computer is getting confused. Why don't you try it with traction control on full off?
05-18-2006, 10:45 PM
#5
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35000km...
Try to floor the car from stand still to end of 3rd gear... (red line please)
A country highway recommended...
Any hesitation high above? https://www.rx8club.com/australia-new-zealand-forum-37/hesitation-high-rev-found-solution-87376/
It is worth taking the spark plug down and have a look.
Try to floor the car from stand still to end of 3rd gear... (red line please)
A country highway recommended...
Any hesitation high above? https://www.rx8club.com/australia-new-zealand-forum-37/hesitation-high-rev-found-solution-87376/
It is worth taking the spark plug down and have a look.
05-18-2006, 11:19 PM
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Yep, I was thinking spark plugs. 
Have you ever had any difficulty starting the car cold? (if such a state can be said to exist in Cairns
) And by difficulty, I don't mean it won't start, just that it cranks a little more than usual 
There has been an "upgrade" available from dealers for cars built pre- March 05 comprising new starter, battery and plugs.
The other possibility is that stones may also have damaged either of the O2 sensors relating to the cat, causing a faulty signal back to the ECU, although I would have thought the WDS would pick this up.
Have you ever had any difficulty starting the car cold? (if such a state can be said to exist in Cairns
) And by difficulty, I don't mean it won't start, just that it cranks a little more than usual There has been an "upgrade" available from dealers for cars built pre- March 05 comprising new starter, battery and plugs.The other possibility is that stones may also have damaged either of the O2 sensors relating to the cat, causing a faulty signal back to the ECU, although I would have thought the WDS would pick this up.
05-19-2006, 12:22 AM
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Does this happen when engine is warm? ie in the optimum operating range. I have had something similar happen to me but it was when I stupidly tried to over rev the engine when cold. D'OH 
Last edited by generis; 05-19-2006 at 12:32 AM.
05-19-2006, 02:47 AM
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Thanks guys.
I did some 'testing' this arvo (with traction controll off off and in operating temp). That's my excuse for being a hoon anyway!
I'm thinking that it is spark plugs as you say. I should've thought of that but sometimes you forget the simplest things when you're problem solving :P
Its going in for a service on monday and I'll let you know how that goes also. If it turns out to be spark plugs I'll have to appologise for the double post
Thanks again
I did some 'testing' this arvo (with traction controll off off and in operating temp). That's my excuse for being a hoon anyway!
- There is hardly any power above 6000rpm (I didn't get up to 9k but the revs were building very slowly it seemed)
- Left a cloud of smoke behind when accellerating from stand still to near redline (in first), but not subsequent trys (perhaps happens on first WOT). The cloud seemed to be near where I first started WOT (or wind blew it back)
- Still a hesitation at 4000 with Traction off
I'm thinking that it is spark plugs as you say. I should've thought of that but sometimes you forget the simplest things when you're problem solving :P
Its going in for a service on monday and I'll let you know how that goes also. If it turns out to be spark plugs I'll have to appologise for the double post
Thanks again
05-19-2006, 03:09 AM
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Haha, I hope so. Though I'm worried that they will blame it on the O2 sensor.
But dirty spark plugs would probably explain the hesitations, and a dirty MAF sensor would explain the richness wouldn't it?
Now that I think of it, I recall my service sheet saying that they used some sort of cleaner on the injectors, I also remember somewhere saying that you're not supposed to do that. Hmm...
But dirty spark plugs would probably explain the hesitations, and a dirty MAF sensor would explain the richness wouldn't it?
Now that I think of it, I recall my service sheet saying that they used some sort of cleaner on the injectors, I also remember somewhere saying that you're not supposed to do that. Hmm...
05-19-2006, 03:12 AM
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Originally Posted by Evergrey
Now that I think of it, I recall my service sheet saying that they used some sort of cleaner on the injectors, I also remember somewhere saying that you're not supposed to do that. Hmm...
BTW, dirty plugs would explain the miss/choppiness, but not the rich smell of petrol you report. I think they need to look at the MAF and other sensors
05-19-2006, 06:49 AM
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I'd say if it's a "Choppy" power delivery you talk to the man himself at www.rx8club.com.au
Hahahahaha, God I'm funny.
Hahahahaha, God I'm funny.
05-22-2006, 02:38 AM
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Alright, put the car in today, all I have to say is *cheezy grin*. I think I had almost forgotten..
Here's a summary of what they did:
The spark plugs were replaced with hotter ones as apparently the original ones are too cold.
Interesting thing is the engine mounts on order...
The car runs beautifully now, it's producing the power up past 6000 as well, and I couldnt reproduce the hesitations in my short time testing. I couldnt pick up any strong petrol smells after stopping the car (this was done in the open though)
They are going to replace the engine mounts when they arrive as apparently its happened before. What do you guys reckon?
I will update the main post with the solution once they complete the work so that this thread may be of use to people searching.
Here's a summary of what they did:
Replace Spark plugs as per mazda tech bulletin for Running rich
Engine Mounts are on order for the "Running Rough"
Spark Plug Leading H x2
Engine Mounts are on order for the "Running Rough"
Spark Plug Leading H x2
Interesting thing is the engine mounts on order...
The car runs beautifully now, it's producing the power up past 6000 as well, and I couldnt reproduce the hesitations in my short time testing. I couldnt pick up any strong petrol smells after stopping the car (this was done in the open though)
They are going to replace the engine mounts when they arrive as apparently its happened before. What do you guys reckon?
I will update the main post with the solution once they complete the work so that this thread may be of use to people searching.
05-22-2006, 03:05 AM
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Evergrey.
Sounds like it is the spark plug and it is nothing to do with the 'coldest' of your plug. I run colder plug than stock. It is just dirty!
I don't think you have to pay for those - since there is a letter out for dealer to install hotter than stock plug as a warranty measure.
Engine mount replacement are common place. I must find a way to change mine before warranty runs out. Do you have vibration noise on idle?
Sounds like it is the spark plug and it is nothing to do with the 'coldest' of your plug. I run colder plug than stock. It is just dirty!
I don't think you have to pay for those - since there is a letter out for dealer to install hotter than stock plug as a warranty measure.
Engine mount replacement are common place. I must find a way to change mine before warranty runs out. Do you have vibration noise on idle?
05-22-2006, 03:07 AM
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Hmm that's what they told me anyway. I do have a vibration noise, now that I think of it, it's more noticeable in neutral with the clutch out.
Yeah this was all done on warranty.
Yeah this was all done on warranty.
05-22-2006, 03:28 AM
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Taka
Possibly writting a letter to Mazda asking them to extend the warranty on a known engine mount fault , they may agree to fix it even after the 3 year warranty period if you require it .
Possibly writting a letter to Mazda asking them to extend the warranty on a known engine mount fault , they may agree to fix it even after the 3 year warranty period if you require it .
05-22-2006, 04:56 PM
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Originally Posted by Evergrey
I do have a vibration noise, now that I think of it, it's more noticeable in neutral with the clutch out.
This whole engine mount thing is getting way too common for it to be a simple case of some bad apples. I recommend everyone get their engine mounts replaced before warranty runs out. This really should have been a recall - or do they only have to do that if it's a safety issue?
Ditto the starter motor, battery and plugs - also under engineered from factory (until later cars).
05-23-2006, 02:24 AM
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Originally Posted by Revolver
Precisely my symptoms Evergrey. They changed the mounts and hey presto back to quiet, smooth idle.
This whole engine mount thing is getting way too common for it to be a simple case of some bad apples. I recommend everyone get their engine mounts replaced before warranty runs out. This really should have been a recall - or do they only have to do that if it's a safety issue?
Ditto the starter motor, battery and plugs - also under engineered from factory (until later cars).
This whole engine mount thing is getting way too common for it to be a simple case of some bad apples. I recommend everyone get their engine mounts replaced before warranty runs out. This really should have been a recall - or do they only have to do that if it's a safety issue?
Ditto the starter motor, battery and plugs - also under engineered from factory (until later cars).
05-23-2006, 05:19 PM
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Originally Posted by RXVIII
I believe I have a similar noise that Mazda claims is “normal” clutch noise and not a problem. Is there a way of checking whether the engine mounts are giving rise to the problem? If the dealer is not willing to consider, under what pretence can you have them changed under warranty?
Do you only hear a noise or have you also noticed increased vibration in the drivetrain? Tell tale sign is increased movement of the gear stick at idle and in neutral (i.e. clutch OUT). If it's only a noise what does it sound like, when do you hear it and does it increase or decrease?
Where are you located and who is the dealer?
The quickest way to demonstrate that your dealer is trying to avoid the problem might be to arrange simultaneous service bookings with another forum member's car (assuming his/her car doesn't have the noise). Bit tough to say it's normal if the other car doesn't have it.
05-23-2006, 06:46 PM
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Mine (the drivetrain) sounds a bit like a tractor or something diesel powered when I take the clutch out, when I put it back in it kind of sounds like a drill winding down for a short time. Obviously easier to hear with the door open. Hard to explain any other way.
05-23-2006, 11:52 PM
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Originally Posted by Evergrey
Mine (the drivetrain) sounds a bit like a tractor or something diesel powered when I take the clutch out, when I put it back in it kind of sounds like a drill winding down for a short time. Obviously easier to hear with the door open. Hard to explain any other way.
You'll certainly know once the mounts are done. When is that happening?