bagachin

Hi guys

This problem has been bothered me for years now (literally).

I constantly experience the jerkiness right from the second i push the gas peddle or let go the peddle at around 3000PRM range on any gear from 1~4th. It happens when the gear is engaged, not when i just about to shift gear. I need to be extremely gentle on the throttle when i accelerate/decelerate to barely avoid it. If i start tapping the accelerate peddle, the car will bunny hopping/bounce like crazy.

Coz it's very hard to describe that feeling, i am quoting the other memeber here, see if you can get a better picture. (PS. Research done!)

".... excessive rubbery jerkiness every time you accelerate or decelerate. I mean the second you depress the accelerator pedal or the second I decelerate, it feels like you are being chain-pulled by another car. It's like a double or triple bounce.."

I have done almost everything i can here.

Long battle with Mazda dealership, they claimed they've checked everything include, throttle body, engine mount, ignition coil, change clutch, spark plug, clear memory. No improvement. At the end, dealer just told me it's the "characteristic of the car when it gets more mileage"........ya....sure....

I went to rotary engine specialist, ProMaz, they also checked those things which normally could cause this symptom, but the mechanic can't find anything. They acknowledged the problem, but just can't find where it is. $250 labour, nothing changed at the end......erm.............surely not going back...

I then changed the spark plug & lead and gearbox oil and clear the memory. It helps a bit, but still jerky after all.

I am out of idea now. I have driven other RX8s, and they don't behave like this, so i do not accept this behavior as "normal" just like what Mazda dealer BS me....Please help if you have similar problem in the past......it's a very nice car, but with this kind of jerkiness, it's way too excessive to my taste......and i don't want to admit defeated!!!! Thanks!



Cheers


Eian

DeViLbOi

iTrader: (1)

Year?
Miles?
Mods?
Redline Often?
Grade of Gas?
Change with engine or exterior temps at all?

zoom44

which of them- dealer or ProMaz- actuallyu dropped the exhaust and looked in the cat?

you're in australia?

tanky41

I have the same problem, mazda have given up also, i had a new engine, new catalytic converter,engine mount, mine has the same symptoms as yours and mine has a fluctuating idle which revs from 1000-3000 revs on its own and stalls easy at roundabouts and junctions ,,has anybody had these problems and been succesful at curing them ? very jerky at excellerating and decellerating

ShinkaEvo

iTrader: (3)

When is the last time you replace coil?

bagachin

Year - 2005

Miles - started from around 25000KMs

Mods - started from only has the aftermarket exhaust fitted, but took out and replaced with stockie, but symptom still exists.

Redline Often - Well....not as often as i have been told to.

Grade of Gas - Shell Optimax 98 octane

Change with engine or exterior temps at all - I can feel the jerkiness is VERY slightly, yet noticeably less pronounced when the car is cold. Or maybe I don't want to damage the engine when it's still cold, so give very little gas when starts.

bagachin

It's the Mazda dealer replaced my aftermarket exhaust with stock one. However, at that time, my setup is aftermarket exhaust with aftermarket high flow CAT (new). And when they put the stockie back, it's the stock exhaust with stock CAT. But no difference at all..

Yap...from Australia

bagachin

So you meant after the engine is replaced, it's still jerky? if yes, at least i know it's not the engine...?

bagachin

The car is done 50000+KMs now, haven't changed the coil. However, at the time Mazda dealer as well as ProMAZ were checking, none of them think my coil has any problem and need replacement. Mazda even replaced one when testing (not sure if they took it back though :P)

bagachin

Is it the one you reset by stepping on the brake for around 20 times? If yes, i have done that too....helps a little, but problem still there

bagachin

Anyone?

oltmann

Ever tried lower octane? 92 RON I think it is. Lots of us run better on 87 AKI.

Just a random idea.

SARRAS

In Australian cars there's a big sticker inside the fuel flap that states 95RON Minimum...

My 20cents worth... if it isn't the engine then surely it could be one or both of the electronic controllers in either the accelerator pedal or the throttle body. This would obviously be expensive as new parts so maybe score one of each from a wrecker and see if they make any difference.

felix92

I doubt you're still around but if you are, did you ever find a solution?

I've got an '07 6sp and it started doing exactly this about 2 weeks ago.

I've had the car from when it was 25k miles to now (47k), so it's not that I don't know how to use a clutch or am changing gears too soon as has been suggested in https://www.rx8club.com/series-i-tro...speeds-168961/

Sparks and plugs Plugs, coils, and leads were done at ~30k. I just did a 0-60 test and it was under 8s with a very bad 1-2 shift, so I don't think it's lost power. I don't really have the roads here to test again.

Oils I do as often as I should. Gearbox was filled with redline at ~35k (everything is in miles for our american brothers btw). Filters etc. too.

Reset the KAM and NVRAM, couldn't notice any difference. No CEL or codes (except one U0073 from probably an abs module, been there a while).


I suspect its either a clutch issue or a throttle sensor/actuator issue. I think I noticed the clutch slipping randomly in 3rd the other day but that stopped immediately and hasn't come back. The clutch gets squishy after I park it hot and come back the next morning, but that has been happening for a while too. Fluid level is fine and there's no visible leaks.


So if you're still around bagachin or anyone has any suggestions please let me know

UnknownJinX

When you say sparks and plugs, does that include coils? Older OEM coils don't last very long.

When was the brake/clutch fluid last changed? It should be done every 2 years regardless of mileage as brake/clutch fluid is hydrophilic and will absorb water over time, which diminishes its effectiveness.

felix92

Thanks UnknownJinX, whoops yes I meant sparks and coils (and leads). Will edit my post.


That is a good point actually, I haven't done the fluid in the 2.5yrs owning the car so it's probably been more than a few years. It is still clear though and not really what I'd expect bad fluid to feel like. The squishy clutch I mentioned goes away after pumping the clutch a couple of times and is supposedly due to the line routing near the exhaust and not something to worry about. Though it was a forum post so who knows.

I will definitely flush the system when I get the time.

Until then has anyone got any other suggestions or easier to test theories?


Thanks

hufflepuff

fuel pump or fuel pulsation damper..? i'm having somewhat similar driveability issues and am trying to run down the mazda troubleshooting chain.

M A Z D A

felix92

I resolved my issue purely by luck.
I went away for a few weeks in the middle of our winter, and parked the car outside.
When I got back I went to start the car on quite a cold night and the engine would run but would barely respond to the accelerator. I checked the OBD error code and it was in limp mode because of a throttle issue. I let the car idle for a while, tapped the throttle body a couple of times, shut down the car, cleared the codes and restarted. Limp mode was gone, but the idle was bouncing around from 1k to ~3k.

After a good hard drive this resolved, but the initial jerkyness remained. I figured it must be an issue in the throttle body, so pulled the intake apart and felt a bit of a ridge where the throttle blade rests when it's closed, so cleaned as far up into the intake as I could reach without disassembling the throttle body with some brake clean and rags and a fair bit of oil/carbon came out. I suspect that the jerkiness was a result of this old and very thick, sticky oily mess jamming up the throttle blade a bit, and that it sitting cold for a while jammed it to the point of causing limp mode.

However, at the same time I pulled the MAF sensor out for no real reason other than to take a look, thinking maybe I should clean it while I was in there. Instead when I removed it I noticed that the O-ring that seals the MAF sensor housing was broken. I replaced it with an O-ring from the local hardware store, put everything back together, and now things are running fine.

Some jerkiness remains, but it's much, much better, I think I only notice it now because I am looking for it, had I not had the issue before I wouldn't notice at all.

tl;dr, check to see if there is any build-up in the throttle body, and check to see if the MAF sensor is properly installed (with o-ring)


-Michael

hufflepuff

Hey Michael,

Thank you very much for sharing. I wanted to confirm your exact symptoms to compare to mine. i am logging actual throttle position vs commanded throttle position and haven't seen much error. i have another post that talks to my symptoms and car condition (https://www.rx8club.com/series-i-trouble-shooting-95/sometimes-lean-sometimes-rich-hesitation-power-loss-%5Bdata-log%5D-268268/#post4867930)

But in essence:
- Car will lose some power, or almost cut all power, while accelerating. Variable severity and duration of power loss.
- Issue happens at both part load and WOT.
- Issue happens at all RPMs, have felt it happen at 2500 and 8500 rpms.
- No CEL, no misfire code.
- So basically, no consistency with respect to throttle position or RPM.
- Issue tends to happen once the car has been fully warmed for minutes.

felix92

Your issue sounds a little different to mine, it's somewhat difficult to explain but it definitely wasn't coming and going, it was every time I stepped on the accelerator. This thread has a bit of a description of the issue https://www.rx8club.com/series-i-tro...speeds-168961/
If I was off the gas pedal, but in gear, foot off the clutch, anywhere from 2k up to maybe 5k, and mashed the accelerator quickly to the floor, I would get 3 or 4 surges that felt kind of like the bunny hopping you get when first learning to drive, or as if you were bouncing your foot up and down on the clutch or accelerator.
I tried logging and graphing the pedal and throttle position sensors, and if i did the same as above but tried to only depress the gas pedal to ~50%, the pedal position and throttle position seemed to spike up to ~75% then drop to 40 then up to 50. This was most likely due to my foot being fairly inaccurate and the jerking of the car itself.
I did find if I rolled onto the gas a bit more gently I didn't experience the jerkyness nor the spike in the sensor positions. Once I was already on the gas (pedal position at maybe 10%), and then mashed the pedal to the floor, there wouldn't be any jerking.
I'm not sure if it was an issue above ~5-6k RPM as I'm cautious mashing the pedal up there in first or second and it's fairly illegal in any other gear here. I think it was fine though.

I also didn't notice any major lack of power (once the jerking subsided) and accelerating hard from a stand still was fine, it was really only a problem going from coasting to accelerating.

I hope this helps in some way