Hey, I own a 1987 RX7 Turbo II which comes standard with a 13b engine and manual 5 speed transmission. Well my problem really is that under 3000 rpm, in neutral or in gear, the car won't hold idle revs during slight acceleration. Now i correct this by accelerating over 3000 rpm but whenever i roll off, say from a stop sign, the car doesn't hold idle under 3k and begins lunging foward and suddenly stopping and lunging foward again, as if someone was pressing the brake while you are accelerating. But like i said before over 3k rpm it goes like normal. My engine is stock. And i really need to figure out what is going on before i start using this car as my daily driver. if anyone can help i would really appreciate it.

 

Adjust your throttle position sensor, and check for vacuum leaks. That should take care of the 'bucking' you are seeing.

http://www.fc3spro.com/TECH/HOWTO/TPS/tps.html

 

so that'll fix it eh? hmm thanks. oh does that affect the performance of the car in any way?

 

Yes, but not a severe ammount. Basically it sounds like it's pretty far out of whack (or has spots where it blows open and doesn't read anything) which cause the hesitation/bucking feeling. You can also try to check the error codes and see that yields anything.

 

so basically i have to replace that tps huh? someone else had told me before it could be the map sensor. but any lead to what exactly is causing it? or is it just the tps?

 

As the page I posted suggests, test the TPS on the car to see if it has any bad spots, if it doesn't, adjust it so that it's at the right spec, this is a pretty common thing to check. After that, check the obvious things such as vacuum leaks, try adding a few more grounds from the chassis -> engine and battery -> chassis, but of course check for error codes, that'll tell you right away if there's something else causing the problems.

 

I had the exact same prob with my 7 when I got it. In the end, I realized that the TPS had a blow open at about 1/4 throttle, causing the check engine light to flicker and drive me up a tree. I needed a new TPS, but setteled for used from a helpful fella on these very same forums. Trust me, for the lifetime of a vehicle, I would rather spend $30 a couple times for a used TPS rather then $350 for a new one once or twice.