autocrash

My car (1989 GX) has some issues.... today yet another made itself known:

When starting my car, it initially runs at 1500 RPM, I used to be able to "kick" it down (give it a quick rev) to a more reasonable 750 RPM idle speed (before the car is warmed up). I had assumed this was the warm-up cycle... (am I wrong?) If left idleing at 1500RPM, the revs would eventually begin to fluctuate lower as the engine warmed up and finally drop to dead on 750 RPM idle.

Now, my car still starts at 1500, but if I try to kick it down it will drop rapidly to around 300 and then stall. If I allow the engine to warm up using the normal 1500 RPM warm up cycle it can be kicked down to a fairly even idle, but the idle is now 500RPM

This has happened over the course of just a few weeks.... and the car has been sitting during that time (being started and allowed to warm up occasionally, maybe actually driven (approx. 5 minutes driving) twice during that time period...

Any thoughts? please??

J-Rat

iTrader: (2)

My car has some of these strange idle issues too. Mine idles at the optimum 850 at first, but after a good pull, or just a rev up, it idles at 1500 or so. Snap the throttle, and it goes down. From what I was able to gather today, it wasnt the TPS since I swapped mine out. My theory is that the throttle assembly is binding and needs to be lubricated. I did just that a few hours ago, and havent tested the results yet.

May be something to look at.

Rat

rx-7fc

my car almost has the same problem but it will idle at 1500rpm and if you start it up it will be at about 800rpm but if you rev it past 1500rpm it will not come down and if you get to come down it will want to die and some times it will die and when you start the car but it warm you have to sit there for about a min to warm it up or it will die

autocrash

J-rat: you'll definately have to share the results... but I think my problem is different from yours, my idle starts at 1500 and then after i blip the throttle it drops.... and most often dies...

J-Rat

iTrader: (2)

Have you checked your initial idle mix? The initial idle is a combination of 3 things...Timing, air (under the blind cap on top of the throttle body), and the variable resistor (I believe this is by the ambient pressure sensor). You have to ground the initial set connector and adjust these for proper idle speed. Once this is done, the TPS should compensate for loads. Generally, the variable resistor shouldnt be touched unless you have made modifications to the engine.

Rat

autocrash

J-rat: worth a shot... yet another weekend project .....lol... it just never ends....


Thanks for your help!

J-Rat

iTrader: (2)

Tell me about it, I am still having my problems too. Seems that my idle works good unless I floor it. THen it doesnt come back down.

Sucks

autocrash

ah well... it's all part of the experience...

scathcart

sorry this sounds too easy, but stuck throttle plates? cable?

J-Rat

iTrader: (2)

Well, its a little more complicated then that.... If you floor the car, the idle comes down, but not all the way. Then sometimes the idle wont come all the way down to the stop (random intervals). Makes doing the TPS adjustment a frigging bitch. Throttle cable is smooth, I havent actually tried to lube the plates inside the body. I was thinking the throttle shaft is getting hung up some how. I know it sounds easy, but its whipping my ***.

Rat

autocrash

what happens when u pull up on the gas pedal? (just shove ur foot under it...) does that drop the idle at all?

J-Rat

iTrader: (2)

The throttle snaps back normally during all operations of the throttle. But if you push HARD on the pedal (I try not too, but sometimes adrelaline takes over), the idle wont come back down all the way. If you blip the throttle about 10-15 times, it will come back down. OR you can raise the hood and pull the throttle full closed, then the problem goes away. I am guessing that something is binding when I apply the throttle hard. Just need to practice some throttle disclipine.

turbotwista

sounds like the problem I am having with mine. Are any of the springs broken or not hooked up? I have a broke one. My idle is at 1500 then if I pull up on the gas petal it will die start it back up and perfect idle till I hit the gas again.

SureShot

Here is the deal. The rotary engine has so little torque at idle that half of the stuff on top of the motor is for idle speed control. The BAC is the main controller of idle speed but it needs help with suddenly switching loads like headlights or AC or heater fan on high. These other accessories have signals to the ECU to open various vacuum bleed solenoids to help out. That is why the idle tune up is fairly complex.

autocrash

ahh... sureshot... any hints on where to start on the idle tune-up? is it listed in the FSM?