I, I've bougth my 93 FD3s disassembled and after almost 1 year, I manage to finish it, and for my great surprise, it started perfectly well 4 or 5 seconds after push the starter... then a friend went for a drive and push real hard (burnouts, high revs) and when he stoped, the idle went crazy, bouncing between 2000-2600rpms... I've changed the throttle position sensor and now the idle it's almost fine but the issue now it's when I try to keep the same speed/rpm, it instantly starts to bounce again (2000-2600)or (3000-3600), depending on wich rpm I try to reach, always with 500-600rpms distance... but if I push the throttle pedal all the way, it reaches the top end rpms just fine... the problrm is mantain the same rpm.
I notice that when it revs down on the bouncing issue, it causes a small vibration/turbulence and it appears to be from the intake filter box, its where I heard the most.
I didn't find any vacuum leaks, It doesn't make any smoke, only gets much pressure on the cooling sistem, but I don't know if it's normal ( if I let it working with the coolant cap of, it sends out the coolant). I also have an oil pressure drop after being working for 4 or 5 minutes, but I think it's in the turbochargers.
I apologise for the long text, but I tried to give all the details... my english isn't also much good, but unfortunately I don't know any better.
I hope someone can help me... thanks.

 

hi, i too am experiencing a slight rpm bounce if i just apply the throttle gently. the revs go up down up own between 1500 - 2000. also at the same time the air to fuel ratio gauge goes up down up down at the same time and have a weird vibration like noise.

are you experiencing any engine flooding?

 

Hi... I don't think so, the engine always starts well... what I notice it's if I unplug the throttle position sensor, it stops bouncing but the idle also drops... and then gives me a code error for the MAP sensor... I don't know if it's the MAP sensor or if it only needs a tune up on the throttle valves, like the throttle position sensor, or the fast idle, or the dashpot... they all seem to work together, I have the impression if I try to tune one, I'll untune the other...

 

replacing tps fixed this issue on mine, fwiw

 

Ok. I'll buy a new one... well, I have to import it from the States or from England, because here I just can't find anything for my Rex. I think I'll also buy a MAP sensor as well, just in case.
I'll let you know the results, when I change the sensors... Thanks.

 

Hi, I'm sorry, but when I said that I've changed the TPS(throttle position sensor), I ment the IACV(idle air control valve)...

 

Hi guys... Well, I just solved my problem of bounced aceleration everytime I pushed the accelerator, just needed to adjust the position of the TPS (throttle position sensor), by releasing a bit the scews that holds the TPS and move it counter clockwise(to the left), then tighten the bolts and leaving them centered in the hole of the TPS... then erase the code errors by disconnecting the negative battery cable and depressing the brake pedal. Thanks for the tips.