03/08/87

As of now, when driving the revs will drop so low that throttle response is lethargic (ie, not crisp). Let's say in 2nd gear slowing down and aproaching a 1st gear turn, so you are braking and shifting simutaneous. So the car has a chance to idle and it will vary depending on how much brake pedal is applied. I guess this is something to do with vacuum and the bac. The bac which I think is the 8mm bolt surrounding a flathead. Well, the idle was bouncing so we adjusted it, but too low IMO.



So when I hit my throttle and let off, the rpms just trail. When I let off the gas I want rpms to drop NOW>Not slowlly trail away. Is there anything I can do? IMO, the best way to do this is with a light flywheel. Can't do that, so what about timing, plugs, injectors, throttle, and could be anti-afterburn valve orthe deceleration control system .

Also, does the fact my exhaust system is not totally 'sealed' have any affect? North of the transmission, near under the hood......"near the reactor" (i like to call it) there is some leak it sounds like AND definately the outlets of the mufflers rusted away and got 4" tips to scavenge as much as possible, but idling with the windows up is a no-no

socalrotor

iTrader: (1)

t2 or NA? 86-88 or 89-91?

You should adjust the TPS LONG before you start messin' with the bac.

texFCturboII

iTrader: (17)

why cant you get a flyhweel?

socalrotor

iTrader: (1)

Why the hell would you tear open a good working setup when it has NOTHING to do with his hanging RPM issues?!

I would unplug the BAC and see how it runs.

Valkyrie

Well, duh. Always fix exhaust leaks, for both performance and safety reasons.

dot_txt

iTrader: (1)

Sounds like you have a few issues (leaking exhaust) to work out before you should be worrying about decreasing the time it takes for the RPM to drop.

About shortening the RPM decrease time:
Correct me if I'm wrong but I believe the only way to do it is a lightened flywheel. You could also go with a lighter E-shaft and lightened rotors but at that point your looking at over 1000 in parts alone without even factoring in the cost of the new seals / rebuild that you may as well do as the entire engine is apart. Other than that I don't think there is a good way to force the RPM's to decrease. At least not anything that will cause a noticeable difference.

The physics of a rotary engine:
One of the primary features of the Rotary engine is the fact that nothing ever has to change direction. The law of inertia states an object in motion stays in motion. Since the rotors never change direction the law of inertia states that the only reason they will stop spinning is the general friction of the engine. In your piston engine, the pistons change direction on every rotation. So the only options you have is either to decrease the rotating mass of the engine internals + flywheel by replacing it all with lightened parts or change your driving habits to use the power of inertia in your favor. Just my opinion though.

Acesanugal

iTrader: (5)

It doesn't really sound like there is anything wrong with your car..?

texFCturboII

iTrader: (17)

uhhhhhmmmm.... wouldn't a lightened flywheel help rev speed?

socalrotor

iTrader: (1)

yes, to a point, but you lose top end. I have a SR motorsport ALM flywheel, and, until I did my CIA, I lost around 7 mph in the top end. 5th gear was close to worthless. This was with a car putting 155 to the wheels without the help of cold air induction. So, im my case, 155 rwhp is not enough to push a sport model faster than 130ish WITHOUT the help of ram air/cai.

It sounded to me as if the ts adjusted and the BAC and now the revs hang before they will drop. Sorry if I am wrong.

Valkyrie

Well, duh. 130 is the NA FC's top speed.

Not to mention you're not going anywhere near 130 when your speedo says you are, depending on your tire size...

socalrotor

iTrader: (1)

Actually, I was running vert wheels with 205 60 15's on the back, which happends to be taller than stock so it might of been faster than 130.

AGreen

iTrader: (11)

On mine, I had the opposite problem. Revs dropped too quickly, and it wanted to shut off. I found the dashpot on the back of the throttle body wasn't properly adjusted, and quickly fixed the problem. If you're concerned about wanting the car to drop revs a little more freely, find the dashpot and adjust it out a little bit. There's a section in the FSM about this, I believe under fuel and emissions.

Valkyrie

That's the stock size... which is already several percent slower than your actual speed (compared to GPS speed). Drop the size to 205/50/15 or even 225/50/15 (which is only 3% smaller than stock), and you'll be even further off.

socalrotor

iTrader: (1)

stock on my sport is 55 series that still doesnt change anything though. I have raced my buddies 350z and he had me topped out @147 on his gps thing a magiggie. The highest I saw was a tick over 140. Either way who gives a crap. On 99% of fc's you are right, the speedos tend to be faster than the actual speed. who knows......just letting ya know what i saw.

slpin

iTrader: (9)

dashpot

arghx

iTrader: (3)

Dude, did you check everything on the throttlebody such as throttle and cruise control freeplay?

The 8mm bolt is for the throttle stop screw if I understand what you are referring to. I wouldn't mess with that unless you have removed your factory idle control stuff.

KhanArtisT

iTrader: (2)

Removing accessories such as the fan clutch, PS, AC and airpump a way to improve throttle response due to the reduced drag on the engine.

Maybe its just my car but I've always hated the lack of throttle response under 4000RPM, above that its nice and responsive though.

How far off should the speedo be? I'm running 225/50/16s and even when I had the stock vert wheels with 205/60s it would read 140mph when I redlined 4th gear. I had my friend in a 350Z drive next to me at 60mph and my speedo was off 3-5mph.

totallimmortal

the dashpot on the tb slowly closes the butterflys even if you abrubtly lift off throttle. Removing it may help, but may cause other problems i've heard, i've never had any tho

Valkyrie

It's normal to be off 3 MPH or so at 60. In fact the manual says to tolerate up to 3 MPH at 50 or so (forgot what the actual test speed is). At 70, you'll be 5+ off, and when the speedo says 100, it'll probably be closer to 10... it gets worse and worse the faster you go.

Just get a portable GPS and you'll know exactly what your top speed is (mine has a max speed function). Not to mention it makes finding places 10000X easier, and you can search them for stores, hotels, and restaurants and stuff.

Chris Boots

ya, adjust the dash pot or take it off and see if A: you like it and B: your engine won't die when you let off because of the throttle closing too fast. On my TII I took it off because I wanted the RPM's to litteraly drop when I let off the gas when I'm on the track. I set my idles to 800-900 RPM's and have never had a problem with taking the dashpot out.