What could make our FD's buck back and forth for a second when throttle is applied or taken away? I've already replaced my pillowball bushings which got rid of the clunking problem but when I first hit the throttle the car will buck for a second or two and just accerate as normal or if I let go of the throttle it will do the same thing. It's worse at lower gears then higher gears. Just wondering what I should look at to solve this and yes the fuel filter is brand new.

 

check the throttle position sensor voltages

 

Does the engine buck or does it feel like the car rocks on the suspension?

 

It definetely feels like the motor is the cause and not the suspension. You can definetely hear the motor change sounds with the bucking. Also the TPS is in spec.

 

I am having a very similar issue...

 

This is a problem I've had with both my 1st gen (sold in 1993) and the FD - and in both cars, it was there from new. I still have it if I accelerate/decelerate suddenly at low speeds in 1st (or even sometimes 2nd) gear. I've gotten so used to it that I never do that w/o partially slipping the clutch to dampen it out (that works very well, BTW). IMO, it's normal with the rotary throttle response/drivetrain wind-up in these cars.

I'm sure some people will say it's not normal, but this is my opinion.

 

Hmm it's still annoying sometimes especially in first gear at low rpms the car hiccups so badly sometimes. However it's happend since the day I got my FD which it ran perfectly then.

 

I know this is rather off the wall, but I had a similar problem on my single turbo FD, but it turned out to be the PPF... It's worth a look at least. Hope that helps and good luck. Mine was sheared in half on one side and torqued like a twizzler.

 

I was thinking about that today... I have the same rocking on a newly rebuilt engine. It ONLY happens when I jump off the throttle - acceleration isn't an issue. At low speeds, the car seems to lurch once a second or so, which I imagine is very similar to what DaveW describes. It actually happened in my old FC and (believe it or not) my old Nissan S13 - so it's not an "FD-only" or even "RX-7-only" problem. It may have something to do with the relatively rudimentary stock ECUs...

I read somewhere that there was a vacuum line to block off or "T" into to stop the bucking during the transition between on and off throttle, though I can't remember what it was.

We'll see if the issue is resolved when I install the PFC after engine break-in.

 

my 89 stock non turbo rx7 is having a hesitation problem when i go to accelerate it seems as it dont want to go and then as it gets higher in rpm it accelerates fine but sometimes it doesnt my friend said it was my tps but how do i fix that

 

^ Try asking in the 2nd Gen Forum