I've loked through the archives and not found a thread on this. The archives are awsome, by the way.
On cold-start only, there seem to be 3 steps in idle speed as it warms. At first I get about 1500prm and it's smooth; after about 3 minutes the car steps down to about 1100rpm and there is a 200rpm surge that cycles every 2 seconds, and this lasts about another 3 minutes; then it steps down to about 900rpm which seems to be the "warm" idle speed and it's smooth again. The car is an '88 base car, 200k km, runs strong otherwise.

 

Not one idea??

 

Whats the problem? Is it your cold start you dont like? Almost every car has a choke upon startup.

 

No, it is the intermediate phaase described above, where the engine acts as if someone is depressing the gas pedal to raise the RPM by 200 revs about every 2 seconds (like one second to get to 1300 and another to drop back to 1100)...... over and over for the whole middle 3 minutes of the warmup.

 

I am pretty sure it's normal. Does the car drive ok? Once warmed up does the idle hold steady? If so everythings fine. My car starts at about 1400 and works its way down as it warms up.

 

well, I've never hear another do the vroom - vroom - vroom thing for a solid 3 minutes as it warms up. Sounds suspicious to me.
It does run fine after warmup.....although I haven't tried driving id during this weird pahse.

 

Huh...dont know. It's cold and lots of fuel. It's not a vacum leak becuase it idle fine. Anyone else!

 

Adjust your tps. And, it still could be a temperamental vacuum leak.
Give the car a tuneup.
Download the FSM and read everything concerning fuel/emissions/engineeletrical. The FSM, when followed step by step, solves most problems.

PS--I don't think that you have a problem. My car loops a little when cold. It goes away and idles perfect when fully warmed up. Rx7's are moody.

 

I'm ok with a little loopiness, but there is another problem that might be related. I have an intermittent "no-start" situation. I have the fuel-pump switch, and have removed the fule-pump check-valve and religiously do the "turn before fuel-pump" start sequence, but still ge the occasional no-start. If you wait a few seconds/minutes it will often start as if there was no problem, and this is not consistent with flooding. It happened today, at night, so I pulled a lower plug and found no spark for 4 or 5 start attempts, then ther was spark and she lit off as if nothing were wrong. Anybody have an idea as to the source of an intermittent no-spark cause?

 

I'm having the same idle surge problem except mine doesn't go away after the car warms up... in fact the idle doesn't drop past 1500rpm even when warmed up. Dunno... I'm 'searching' the site right now for answers!

 

let me know what you find.... I have not found any reasonable explanation, yet.

 

My car does this once in a while. The 'surge' stops if I hit the gas pedal. I think it might have something to do with the throttle linkage. Haven't checked it out, so I can't say for certain.

 

Bad thermowax?

 

Great...... what is thermowax.

 

Mine is doing presicely the same thing. I wouldn't worry about it too much if everything else is feeling ok.
If it doesn't go away then its probably the TPS.

Have fun

 

Uh-oh...

It's part of the throttle linkage assembly on the front on the plenum/upper intake manifold. I don't have a pic handy.

Hang on...

 

Here's the best I could find for now.

http://fc3s-pro.com/TECH/HOWTO/TBM/tbm.html

Lots of pics. Click to enlarge.

 

Mine does the same. As long as it goes away when the car reaches operating temp then what's the problem? If you're trying to drive it while it's doing this you shouldn't be. A car is like a woman: God help you if you try and go for a ride before you get her properly warmed up.

 

mine does this too dont worry

 

adjust the map sensor