jacob

i have owned an '89 GTU for about 6 months now. for the most part, it is a great car. there is one thing i hate though, and that is the low throttle, low speed jerking. it is terrible! say the car is idling, clutch fully engaged, in first gear and you decide to give it some gas. well the car will jerk like crazy! it also jerks big time when you are in a low gear and try to decellerate slowly by using the throttle. its gets so bad sometimes, that you have to push the clutch in to make it stop. so if anyone has had the same problem, or think they know what would fix it, i would be very happy to hear your comments!
thanks

and another thing...i've adjusted my tps, it is set right.
i've also ran a beefier ground to the tps, still no soup.

EX-HONDA

TPS?

ra ra rotory

Yeah man, i hate that jerking, it sucks, i dont know how to fix it, i dont think there is a fix other than put in the cluch. and i have to ask, please explain the TPS is it the (throttle positioning sensior)? how do i adjust it? thanks, good luck on an answer

jeff88

i'd start at the TPS too. You will need a multi meter to test the resistance of the TPS.

Check out www.fc3s-pro.com there is a good how to there. Go to tech, then how to's to find it on the site.

Good luck

Mr. Eccentric

I get the jerks in me '89 too. It's just the nature of the rotary I guess. Unless it's really bad, there's probably nothing wrong at all. The only way to get rid of it is to buy something that doesn't say Rx-7 on it

There's a system in the car that Mazda designed to help cut down on the rubberbanding. It's called a check and cut valve. I think there's some other bits that work in tandem to reduce the jerk, but Mazda knows the car jerks at low rpm and they don't deny it, so you're not the only one by any means experiencing this. Maybe your engine is trying to tell you it's only happy at high revs!

I've driven lots of 5 speeds, and the Rx-7 is a really hard car to drive smooth. No matter how good of a driver you are it will still buck when you lift to decel. The best I can do is lift ultra slow and hope. I find that when I'm driving the car really hard that's when downshifts and lifts and upshifts are fully smooth. I'd bet you find the same thing with your '89.

Trav

Stop it, you'll go blind!

jeff88

I don't know about all RX-7's bucking or lugging. I have an 88 NA that lugs at low speed, low rpm's basically when you are cruising thru a neighborhood and trying to keep it under 25 MPH. I have an 90 Turbo that does not lug or buck at all. I can creep at 5mph which i have to do because i live on a non maintained dirt road.

Oh- both cars have no air pump or avc and no cats on either car.

In my case the 90 is very well maintained and kept on top of, while I have let the 88 go and it just needs some TLC and it would not lug either. So not all Rx-7's have this problem.

mac_dad6

try getting an engine torque brace from racing beat. it drastically reduces or eliminates the bucking your talking about

Phu5ion

just practice driving at those low speeds, i've had to drive in bumper to bumper traffic a lot lately and i have started to learn how the car will react to letting off/getting on the accelerator.

it's mostly just using very slow movements with the accel. otherwise it looks like you don't know how to drive a stick.

Blowtus

While I get what seems to be the typical on / off throttle jerk, (and yeah, it all smoothes out very nicely when I'm mountain range driving) I find my 88 turbo only lurches back and forth somewhat when I'm rolling *very* slowly in first... like 1200rpm or so. it's almost as though you can feel the engine turning round... it just seems to cycle. smooth, lurch, smooth, lurch. Very rarely any sort of issue for me.

Charlie

MelissaRx-7

Yes! Someone else has that problem! I have driven my bf's 86' GXL a couple of times and it always happens!! Even though I'm a fairly *new* stick driver, my bf always just gives me the dumb look and says "it never happens to me when I'm driving" Now I feel a lot better that others have the jerking problem in low gears
Thanks you guys

bcty

my gas pedal it very touchy... it is like a on/off switch more or less.. i hate it for school zones.. very hard to drive slow but just press down the gas and you accel very quckly!! its a love hate thing

Rxmfn7

iTrader: (4)

Hehe, well it never does happen to me when Im driving does it? I think that my car just doesnt like you, she only likes me to drive

von

When my TPS was way off my car would jerk at anything lower than 2500 rpms. It was bad. Now after I fixexd it I can roll at 1000 rpms perfectly smoothly if im concentrating on the throttle. Its never a problem anymore but i do agree its probly bucks easier than a normal car. It just bucks to be you.

PS: that was gay I know

J. Rivera

Low end torque, this car have very low end torque. that's why it jerks!!!

J. Rivera

Low end torque, this cars have very low end torque. that's why it jerks!!!

Matlock

Every car I have ever driven. Only about 20 or so. Does a very similar thing. Low speed 1st, 2nd gear. I belive if you get in any car thats not and automatic it will do a similar thing, unless it excesive to the point of breaking component or dying, I am pretty sure its normal. I am not trying to make you feel stupid in any way but have you driven another car thats a stick in the exact same fashion? When cruising at 10mph in 1st gear my car will do that everytime I barely touch the gas. If you throw it in nuetral while it's bucking does it stop?

It may be a genuine problem, check you universal joints and drivetrain components but I think it's natural.

J. Rivera

Low end torque, this cars have very low end torque. that's why it jerks!!! If it was the TPS it would do it consistently and randomly. Use a voltimeter to check your TPS and with the ignition switch on check the voltage in your TPS and should be .95 Good luck!!

jacob

thanks for the replies!
well i started out learning how to drive on a 5 speed, and have driven many, many 5 speeds in the 5+ years i've been driving. from a saab to a bmw, to a toyota 4x4 on 38's and everything in between, only one rotary however. i drive a 5 speed everyday, so i know how to drive one very well. the problem with this car, is that it takes an enormous amount of effort to maintain a low speed compared to any other car/truck i've driven. if i'm trying to maintain a slow speed in a parking lot, or in traffic, the moment i even think about letting off the gas just a tiny bit, the car will act like i hit the brakes. so when the car slows down, my foot will move forward a bit, just enough to make the car accelerate again. this can easily get into a vicious and annoying cylce. this has happened to everyone who has driven my car for the first time. after 6 months of driving the car, i can keep it from turning into a violent cylce, but the little changes in speed (slow down, speed up, slow down, speed up...) are still pretty annoying and only happen in this car. maybe it is just a rotary thing. or maybe the car is telling me not to go slow. either way, its good to know i'm not the only one out there.
i've thought the problem was my dashpot, but it appears to be working right. maybe the damping rate has gone down over the years, but it still has some damping to it. and my tps is spot on. well thanks for everybody's input! hopefully i can get to the bottom of this....i'll take a look at that torque brace.

Mr. Eccentric

I'm not sure the torque brace will be of any help. From what I know of it, it's designed to prevent the shakes the engine gets when you're just getting the car going in 1st or reverse. My car has only shook like this a few times, but there's no mistaking it. The brace helps stabilize the engines position and eliminates or greatly reduces the tendancy to shake. It may help with the bucks as a band aid solution, but then again it may not even do that.

Rivera, the low torque theory is interesting. I wonder if that's actually true. You got any evidence? Seems feasible enough. I wonder if the S2000 has bucking problems? The hp and torque characteristics on Honda's 4 from that car and the rotary are basically identical.

deadRX7Conv

I haven't tried to drive my car slow so I am not an expert at your problem. Drive faster
Just kidding, I mostly noticed it when I let someone drive it. I guess that driver experience levels are different. Prepare to slip the clutch a little while in 1st at low speeds to prevent the bucking from starting.

Definitely take a look into the RacingBeat(torque brace) and Mazdatrix(STB's with brace). The first gear low rpm hic-up is almost the same as an inexperienced driver pulling away in 1st.

Also check all your mounts. Anything loose/broken in the drivetrain(engine/trans/rearend) will compound the problem.

A poorly running/maintained engine could also add to the problem.

It isn't a low torque problem. If it was, you wouldn't be able to accelerate. Its 'physics', the design of the rotary, and Mazda's poor engine tuning.

It also isn't fair to compare a new s2000 to a 12-16 year old rotary. When the Renesis comes out, compare the s2000 to that!

http://www.zaxjax.com/towerbar.htm
http://www.fc3s.org/how_tos/suspensi...ine_brace.html

EX-HONDA

still say tps

DaleClark

iTrader: (55)

The car should generally be quite smooth. A broken diff mount, broken motor mounts, worn driveshaft U-joints, etc. can all contribute to jerkiness.

In general, don't drive the car below 2000 RPM. Rotaries don't take well to being lugged at a low RPM.

One common problem with shuddering when starting from a stop in first is a bad driveshaft U-joint. I'm fixing to replace my fiancee's driveshaft this weekend for that very reason.

Remember, folks, these are 10+ year old cars we've got. A lot of parts are worn out by the time we get 'em - I've driven enough 2nd gens, though, to know what's normal and what's not normal. Excessive jerking is not normal - probably just drivetrain slop.

Dale

Mark S

iTrader: (1)

My 89 used to rubberband pretty bad as well. I Adjusted my TPS, and it got a little better, but then I ran a can of 44K through the gas tank and it cleared up almost completly. The stuff is kinda hard to find, and it's like 20 bucks a can, but it worked wonders on my car. I'm guessing the problem stems from crud in the intake somewhere, whether it be fuel injectors, or sensors.

Also, I would check your intake duct for leaks, vacum leaks etc. Also, I've heard advancing the ignition timing slightly will sometimes clear up bucking.

chris_stampe

This just started happening to my car. I believe i just broke a diff mount and this is when it started. Either that or when I installed the TII engine. Ill replace the broken mount and tell you if that fixes it.