View Full Version : Hesitation around 7800RPM?


tmak26b
08-29-2009, 07:55 PM
I am at the track now, car seems to be getting a slight hickup at 7800RPM. Car is also down on power from what I can tell compare to other RX-8s and my times from earlier today to later in the day. The difference is around 5mph, most noteable at the top end in 4th gear. You guys have any idea? It is an 06 with 37K, new plugs OEM coils and OEM wires just last month.

Brettus
08-29-2009, 07:58 PM
check your leads are on properly - take them all off then back on again

tmak26b
08-29-2009, 09:14 PM
I will check the wires and plugs tomorrow morning, but didnt someone say teh 7800 rpm hickup is normal?

TeamRX8
08-30-2009, 10:28 PM
No it's not.

tmak26b
08-30-2009, 10:35 PM
My speed didnt drop, but there is a noticeable buzz at 7600RPM or so. I wonder if it is the intake tract changing at 7250rpm since the stock tach is off

miztic
08-31-2009, 10:15 AM
I kind of assumed it was the intact tract changing as well, but 7800 seemed kinda high to be changing.. I also get a little bump right at 7800.
Bought the car last Oct, now have 48,000 miles on it. I was going to change out the spark plugs and coils, but blew my money on tires instead :)

wankelbolt
08-31-2009, 12:29 PM
Is that you, Tom? I was the other RX-8 you were trying to keep up with. :) Good to meet you.

Videos to come. I hope somebody got vid of me spinning down the hill between T10 and T11. :crazy:

There is a brief drop in power (or really just smaller increase in power) at 5250 according to Maurice (aka Canzoomer): "At that point the third intake runner tubes open, and we get a lean spot for a fraction of a second." That's what I was remembering when we were talking about it. So nothing normal at 7xxx RPM.

shazy
08-31-2009, 03:53 PM
well the intake port opens at 7200rpm. I notice it around that high. But at 7800rpm Im fine, so there is definitely something wrong. Clean your MAF... you never know...

docgatorx8er
08-31-2009, 04:07 PM
You might be developing a clogged catalytic convertor. I just burned mine up at MidOhio. It seems to be a relatively common problem. Started with a feeling like fuel starvation over 6500 RPM and got progressively worse. That is about the milage they go at also.

ndhoffma
08-31-2009, 06:02 PM
Ive felt my car do this sporadically as of late... I was gonna try plugs & coils first, since Im due for plugs anyway.. subscribing to see what ends up being the fix for it

G-ReX
08-31-2009, 09:41 PM
Is that you, Tom? I was the other RX-8 you were trying to keep up with. :) Good to meet you.

Videos to come. I hope somebody got vid of me spinning down the hill between T10 and T11. :crazy:Scary spot to go off! Did you head left, right or just explore the track?

There is a brief drop in power (or really just smaller increase in power) at 5250 according to Maurice (aka Canzoomer): "At that point the third intake runner tubes open, and we get a lean spot for a fraction of a second." That's what I was remembering when we were talking about it. So nothing normal at 7xxx RPM.

I don't notice any blip in the 7k range and my data logs look clean (no bobble in the RPM or speed curves).

tmak26b
09-02-2009, 12:57 AM
Is that you, Tom? I was the other RX-8 you were trying to keep up with. :) Good to meet you.

Videos to come. I hope somebody got vid of me spinning down the hill between T10 and T11. :crazy:

There is a brief drop in power (or really just smaller increase in power) at 5250 according to Maurice (aka Canzoomer): "At that point the third intake runner tubes open, and we get a lean spot for a fraction of a second." That's what I was remembering when we were talking about it. So nothing normal at 7xxx RPM.

Hey B, that's me. I think the RPM was indeed 7500RPM on the tach, so 7250RPM is very well be where the hickup occured. I am looking at the datalog, I honestly don't see any drop in speed. So it might just be a noise from the engine. It's funny because I don't hear that driving on the street, only at the race track. Of course I only hear the 6 port at 8000RPM on the street, but not on track.

I am still stumped as to how your car has more mid-range than I do. What do you have on your car exactly again, I need to find something for my next VIR trip. I am still trying to recover from my 10 hour trip, will post some data later this week.

shazy
09-02-2009, 02:55 AM
the base model...