blue smoke and idling problem
 

I bought a 1990 GTU a few months ago, and am slowly getting it back to good running shape.

When I bought it, I drove it two hours back home. After getting it home, the engine was idling wildly, from 1k to 3k and back. I parked the car, and I haven't had this problem since then.

The engine does do the normal 3k warmup cycle, then drops down to 1.5k and then somewhere below 1k. However, depending on the day, it sometimes drops well below 700 rpm and sounds awful. If I turn the idle adjustment screw to get it closer to 700-800, then the next day it can idle as high as 2000rpm (after warming up).

In case it's relevant, the exhaust also lets out a popping sound when I let off the throttle.

I haven't been too worried about any of this yet, since the engine still produces good power and it doesn't seem to affect driveability too much.

However, this morning the car was running a little rough. As I was pulling out of my neighborhood, I accidentally pulled out in 3rd instead of 1st, the engine died and wouldn't start again. After letting it sit a bit and cranking again, it finally started, but when I revved the engine, it let out blue smoke for about 30 seconds.

The engine is no longer running rough (except for the aforementioned exhaust sound). However, if I rev the engine just the right amount, I can hear a scraping sound. I can't tell where it's coming from, but it sounds perhaps like it's coming from below the engine. If I don't rev the engine enough, I don't hear the sound, and if I rev it too much, I don't hear it. I don't know what speed I'm revving it to, because I can't see the tachometer with my head under the hood (and there was only one of me this morning).

Is the blue smoke related to the idling problem?

What might cause erratic idling speed?

Thanks,

Paul

Raising the idle is a bandaid, it won't fix the problem. In my sig is a link to the online FSMs, download the S5 edition closest to your year and follow the trouble shooting guide in the engine/emissions section.

As an offhand guess, clean and check the BAC and check the tps'.

Blue smoke usually indicates oil burning. If there's enough of it being burned, it can foul plugs and give poor idle quality. I don't believe that's the cause of your erratic idle though.
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Unfortunately I can't see the link since I'm still a newb:

Type the following in:

wanklel.net.~kwright/cars/rx7/manuals.html

http://www.wankel.net/~krwright/cars/rx7/manuals.html

you need to set the set the idle screw when the car is warmed up and already idling




it stalled, it then flooded, oil got past the control ring since it wasn't warm yet
again not too unusual for these cars

has to do with the clutch, most likely throwout or realease berring
my 90 FC make no noise at idle
but my 91 does
and several other cars I've had did it to (most notably my former FD before I replaced the clutch - but that is a horror story all unto itself, but I digress)

probably not, other than (as someone already said) you may have fouled plugs from the oil

the idle prob is more likely to be a vacuum leak or TPS issue

grab a Haynes manual the next time you're at an auto parts store, I still see them on the shelves

then go forth and change all the fluids, plugs, wires, make sure all the grounds are good, etc....

Driving around town for half an hour in 70 degree weather should be enough, no? (which is what I typically do)

Ok, that makes me feel better, since I already knew about the clutch.

Which should I check first?

I've got one. They're not easy to find for this car.

Already done the fluids and plugs, but not yet the wires nor vacuum lines.

Thanks!

Paul

Valve guides or piston rings:rlaugh: