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Hello guys!
So, I recently replaced the trailing ignition control unit on my JDM '85 12a Turbo (EFI). Now the car works like it used to and I'm VERY happy with the results!
I still have a little problem with idling though. I would have thought changing the ICU would fix the problem, but nope...
Description: When cold, the idling makes me think a bit of a cammed V8 engine. It has some kind of a weird rhythm to it that has nothing to do with a rotary. Once the engine gets a bit warm, idling stabilizes itself but way too high, around 1300rpm. If I give it a bit of throttle (up to 3500-4000rpm) then let the RPM fall down to idling, it will stabilizes around 700rpm (a bit too low), but just merely touching the throttle, sends it back to 1300/1400rpm right away.
If I shut down the car for a couple of minutes, then turn it back on, the idling will be CammedV8-ish for 30s, then stabilize again at 1300-1400rpm.

Other than that, everything is great with the car. No problem at all, great throttle response and tons of fun. It's just this idling problem that is a bit annoying since my car is daily driven.

If anyone has an idea as to what might be wrong, I'm all ears

Thanks,

Flavien

I don't have a clue what the problem would be. But maybe uploading a video on Youtube might help a bit?

Hobbawobba wrote:I don't have a clue what the problem would be. But maybe uploading a video on Youtube might help a bit?

OK I'll do that tomorrow then
11pm here already so...

Sticking throttle cable or throttle body?

KiwiDave wrote:Sticking throttle cable or throttle body?

My first thought to Dave.

myatt1972 wrote:

KiwiDave wrote:Sticking throttle cable or throttle body?

My first thought to Dave.

So I just came back from the car... Of course, because I was trying to shoot a video it hasn't caused as much problem as usual
Nonetheless, you can hear what I mean by weird CammedV8-ish idling at 4min40 and 6min05 in the video.
I will look for a slightly stucked throttle cable, but I doubt it is the problem... Could be nonetheless so I'll WD40 the shit out of the cable, we'll see

Oh that does seem quite strange (to me at least). Wouldn't a stuck cable would keep it at the same RPM rather than fluctuating? Love the car by the way!

Hobbawobba wrote:Oh that does seem quite strange (to me at least). Wouldn't a stuck cable would keep it at the same RPM rather than fluctuating? Love the car by the way!

Yeah, I doubt that's the problem either... To make it jump back from 700 to 1300rpm, I also merely have to touch the pedal, not even really pressing it. Not pressing it enough to make to gain 600rpm anyway...
And thanks

Check all of the ignition components, plug leads, coils, distributor cap and rotor etc. Often these things can be electrical when they seem mechanical.