I have a 93 FD Touring and I've been experiencing something weird lately while cruising around. between 35 and 40 I have noticed a slight jerkiness that gets worse if I don't accelerate, deccelerate, or change gears. The engine is running between 2000 and 2500 rpm in fourth gear and 2500 and 3000 rpm in third gear. These are the only two gears it does it in. I'm just wondering what might be causing this, and more importantly if I should be worried. It doesn't do this in second gear at higher rpms and in fifth gear at really low rpms which makes me wonder if it has something to do with the turbos beginning to spool up.

 

you should not drive the it like other manual car.
Change your gear around 3500 to 4000 rpm. that is how u should drive.

 

ok, but is there any reason for why it does this? I know these aren't economy cars but I would like to get as good of mileage out of mine as I can. The other thing I've noticed when it starts to jerk is the oil pressure drops to the point where the light turns on sometimes.

 

You're oil gauge is probably wrong. If your talking about the car "bucking" back and forth then mine does the same every once in a while, but not severely. In 1st gear however, if it does "buck" it will be violent. Almost all rotarys will buck if cruising under 1500rpm. Although I don't know exactly why they buck, I don't believe it's a big issue unless it gets violent.

I can say however, that it is a good idea to stop the "bucking" as quickly as possible, since it's obviously an extra and unnecessary strain on the driveline. Easiest way to stop it at low speeds is to push in the clutch and then engage it again. If your at a good speed (above 15-20mph) either add gas or get off the gas completely and get back on after it settles. I notice my car "bucks" one time after I get off the gas when cruising. Don't know why.

I just had to learn to drive it differently. I have noticed when I watch racing on tv, when the cars (piston or rotary) are cruising, like during a caution lap, their cars start to "buck" pretty hard. So I like to think mine does it because it's just a natural race car thing.

I've also learned how to make my car "buck" without stabbing the gas. It's hard to explain, and pretty useless to need to know. But it sounds cool when your going down the road in traffic all like.... waaaaaaWAaWAaWAaWAaaaaaaAAAAHHHH!!! It would be cooler if I had the whining of a dogbox.

 

yeah, that sounds about right, and it's not under 1500, it's usually between 2 and 3k. the clutch thing is what I usually do, but thanks for all the help guys. I have a hunch why the oil pressure thing is off, there's a small leak, but that's getting fixed next week.

 

The under 1500 is usually due to the tune. But in all fairness the "bucking" can happen at any rpm as long as your cruising...

Keep in mind that the FD's factory oil gauge is the shittiest gauge known to man. I should probably rephrase that to say that the factory oil monitoring system is pretty horrible. Usually the gauge or the sending unit goes bad. My gauge readings are always inaccurate bouncing from 0 to 120+ randomly. Rotary Performance says that the FD factory oil monitoring system was one of the "cut corners" to get the price of the car a little lower, and that Mazda decided to cut corners with that system because rotarys never have oil pressure issues that are unrelated to catastrophic failure. Basically if you have a REAL loss of oil pressure, its usually due to a massive motor failure, resulting in the lose of pressure being the least of your worries.

 

make sure your grounds are all good and clean. I solved a bucking problem similar to this by adding some new grounds

 

lol, that's good to know, I'm totally stock at the moment, so I'm assuming that might have to do with the difference cuz yours doesn't look stock

 

Interesting... Don't see the correlation but then again, I'm not a master at this ****.

 

which grounds did you have to replace? or did you just start replacing them all?

 

bucking can be caused by a lean condition. But i don't know what could cause that in your situation.

 

don't know, running a lower octane gas? I'm running 90, cuz another guy here in town with an FD said his runs just fine on it.

 

Sounds like the 3k rpm hesitation. Supposedly it has something to do with the staging of the 2ndary injectors. Some claim adding ground straps help but I doubt it. If you get a power fc it will go away.

 

Although my car is so heavily modded than it 100% requires 93 and prefers 100. I have to say that with any RX7 I would never chance it. Stock or not I say run the best fuel you can get.

 

I doubt the fuel is related it wouldn't have enough load on the engine to only hesitate at those rpms. But you should still run premium fuel if you boost your car and do full throttle runs from time to time. Which if you drive an rx7 i sure hope you do.

 

oh yeah, addicted to boost is an understatement, it's just hard to find higher octane in Lincoln, NE, it's actually easier to find E85 believe it or not than 93. The power FC is getting put in over the winter hopefully

 

I have a power fc on mine and I still get slight bucking issues.. could it be caused by the fuel injector duty going to 0% when you are off the throttle when decelerating?

 

Is your name really Thadeous?