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First gear accelaration feels flat after 6k rpms

Old 10-27-2010, 10:15 PM
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First gear accelaration feels flat after 6k rpms

I do not know if there is something wrong with a car or it is how it suppose to be, but when i am going WOT - pull in first gear feels slower then in second (as I go WOT through the gears).

It feels like from 6k rpms to 9k rpms there is not much change in acceleration, I do not get any push in to the seat as rpms climb (as if power is about the same through that rpm range), while after shifting to second - it feels slightly better compared to 1st gear -- Car acceleration increases as rpms rise from 6k to 9k.

I am not sure if I am just used to my tiburon (drive it most of the time) and RX8 just feels like it has lack of power (although car should feel faster in 1st gear then 2nd) or something is indeed wrong.

Car has 34,000 mi new plugs, seafomed 2 months ago, acceleration has always been this way since i got it with 23,000 mi

Last edited by tibyABv6; 10-29-2010 at 04:57 PM.
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Old 10-27-2010, 10:40 PM
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Mine is about the same. You blow through first, the flat torque curve is more noticeable.

Was it strong before? You should feel a dip at about 6k RPM when the secondary ports open, so you get that slight hesitation.
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Old 10-27-2010, 10:54 PM
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the acceleration in 1st is limited by engine resistance (which you can feel it just by doing WOT in Neutral), in 2nd gear when wind resistance is still relatively low, speed goes up faster as rpm climbs. after that wind resistance starts to affect.
but 1st gear should always be the quickest acceleration no matter what. its physics.

Last edited by jasonrxeight; 10-27-2010 at 10:57 PM.
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Old 10-28-2010, 12:14 AM
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Probably a bad cat
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Old 10-29-2010, 04:31 PM
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Originally Posted by CyberPitz View Post
Mine is about the same. You blow through first, the flat torque curve is more noticeable.

Was it strong before? You should feel a dip at about 6k RPM when the secondary ports open, so you get that slight hesitation.
No accelaration always been the same. I feel hasitation some times when shifting in to second - and landing at around 6.1-6.2k rpms
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Old 10-29-2010, 04:43 PM
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Originally Posted by jasonrxeight View Post
the acceleration in 1st is limited by engine resistance (which you can feel it just by doing WOT in Neutral), in 2nd gear when wind resistance is still relatively low, speed goes up faster as rpm climbs. after that wind resistance starts to affect.
but 1st gear should always be the quickest acceleration no matter what. its physics.
Yes...the lower the gear is the more torque you have - thus it should accelarate faster.

I just cant understand why 2nd gear would feel slightly faster then 1st in rx8,... although i have somewhat of the similar thing in Tib where 4rth feels like it pulls better then 3rd.
There are no CEL light so i hope everything is ok mechanically - cant really know if cat is fine unless it will throw a cell - but car only has 35k mi so it should not be to bad. I thought that coils might not be at top condition, but i dont have time right now to finish my LS-2/Yukon coil kit.

Last edited by tibyABv6; 10-29-2010 at 04:59 PM.
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Old 10-29-2010, 05:55 PM
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It's your Tiburon and butt dyno.
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Old 10-29-2010, 06:34 PM
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My car and at least one other literally went flat from 6K up on the dyno... yes, a real one.
It turned out to be intake related: the SSV actuator was leaking vacuum.

No CEL and no other symptoms
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Old 10-30-2010, 06:05 PM
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Originally Posted by DarkBrew View Post
My car and at least one other literally went flat from 6K up on the dyno... yes, a real one.
It turned out to be intake related: the SSV actuator was leaking vacuum.

No CEL and no other symptoms
hmmm...maybe it is something vacuum related. Because i would think that there would be more difference in acceleration between 6k rpms and 8k rpms (as there is differance of 15whp)

Does any one knows if removing intake tube extension and the actuator (the thing that sits in front of air box and opens up shorter air path-way at high rpms) will hinder performance?

I just plugged up vacuum hose that was going to the actuator part.
SSV actuator is worth checking too
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Old 10-30-2010, 06:15 PM
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Originally Posted by tibyABv6 View Post
I just cant understand why 2nd gear would feel slightly faster then 1st in rx8,...
Because you are starting from a higher RPM in 2nd and 1st goes by too fast to notice the pull much, by the time you get into the power band in 1st it's about time to shift. Also, when starting from a stop in 1st you have to overcome inertia to get the car moving. Lack of low-end grunt with the rotary makes 1st feel slow.
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Old 10-30-2010, 07:54 PM
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I think that the Mazda engineers extracted everything they could from that intake system. I would not touch it except for repair or maybe for forced induction
I posted a long story about my low dyno pull in the Canada forum and how I solved it.
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Old 10-31-2010, 11:01 AM
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Originally Posted by DarkBrew View Post
I think that the Mazda engineers extracted everything they could from that intake system. I would not touch it except for repair or maybe for forced induction
I posted a long story about my low dyno pull in the Canada forum and how I solved it.

Do you know link to it?
Car had damage above bumper support and that thing got crushed ...so i junked it. I figured it might lose a bit power at low rpms but should not hurt high rpms, unless disconecting it messes with ECU
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Old 10-31-2010, 11:36 AM
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Originally Posted by tibyABv6 View Post
Do you know link to it?
Car had damage above bumper support and that thing got crushed ...so i junked it. I figured it might lose a bit power at low rpms but should not hurt high rpms, unless disconecting it messes with ECU
If you are talking about the VFAD in the nose I removed all that and replaced it with the RB Ram Air. All you have to make sure of is that you plug the VFAD nipple on the bottom of the UIM just behind the throttle body. Otherwise you'll have a vacuum leak

Here's the link...
https://www.rx8club.com/showthread.p...ht=dyno&page=9

Remember that this took place over a period of weeks and covers all the stuff we tried to repair the problem until final success with the SSV actuator.
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Old 10-31-2010, 03:24 PM
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Originally Posted by DarkBrew View Post
If you are talking about the VFAD in the nose I removed all that and replaced it with the RB Ram Air. All you have to make sure of is that you plug the VFAD nipple on the bottom of the UIM just behind the throttle body. Otherwise you'll have a vacuum leak

Here's the link...
https://www.rx8club.com/showthread.p...ht=dyno&page=9

Remember that this took place over a period of weeks and covers all the stuff we tried to repair the problem until final success with the SSV actuator.

I plugged nipple on the "sensor" with is mounted on the back of intake box, and wirering that plug in to that sensor i left plugged in. (talking about the yelowish chrome sensor with green wire plug on top of it)

http://upload.wikimedia.org/wikipedi...er_removed.jpg

Should i unplug wire harnish from that sensor and and just close of vacuum at the IM?

Last edited by tibyABv6; 10-31-2010 at 03:26 PM.
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