Lots of gray smoke
 

'94, 5-speed, 83k or so miles, stock except Racing Beat cat-back exhaust. Original engine, original turbos.

Last summer, brought it to a garage I trusted with my other car for a possible coolant leak, help with emissions (it failed) and oil change and got it back running like complete crap.

Took me a while, but turns out the garage had overfilled the car with oil. Did another oil change once I figured it out, and it's been running pretty well since then.

However, right around that time (maybe slightly after, not 100% sure) I started having an issue with the car blowing out a lot of gray smoke when first started cold. It doesn't seem to be oil to me - oil use seems acceptable. I do get a small puff of bluish/gray smoke that I attribute to oil, but this is different. Doesn't seem to be coolant to me as I don't seem to be losing any.
I used to have an '86 with a coolant leak, and that smoke was very white and burned off pretty quickly once started up. This is different.

This smoke is pretty consistent until I actually start driving the car. The smell is pretty sharp, but again I don't think it's coolant - I'm thinking maybe it's fuel. Which brings me to another point - the garage mentioned above had told me they replaced the 'air sensor' (that's what they called
it) since they thought it was running very rich. Not sure if it was the O2 sensor, or what.

Anyway, I can let it run for 10-15 mins or so and the smoke and exhaust fumes are still substantial. It seems the only way to get it to stop smoking is to actually drive the car, almost as though the excess fuel is getting burned more efficiently when driving or something.

I'm pretty ignorant as far as this stuff is concerned, but I'm not a complete dope (I change my own oil and have done tune ups on my RX-7, so I can do some of my own work if I know exactly what I need to do).

Anyone have any suggestions? Could it be the O2 sensor, or anything else the garage may have done because they thought it was running rich? I'm no longer on speaking terms with them, so it would be impossible for me to go down and ask exactly what they did.

Maybe I'm wrong about it being fuel, but from past experience it just doesn't seem like oil or coolant to me. Car does seem to run well, power is decent (though I don't have a boost gauge installed yet, nor have I owned it long enough without issue to really know what ideal power is).
It's certainly in the ballpark though.

Thanks in advance for any help...

Mike

i have the exact same problem...it seems to be worse when its cold out, i'm very interested in an answer to this

Mass huh isn't it still pretty cold up there? have you looked to see if it even gets to operating temps when it is idling? could be condensation. get the cooling sys presure tested. look for bubbles in the filler neck during a cold start-up. 83k is starting to get up ther in miles so it could be alot of things. or it may just be cold.

Yeah, maybe you guys are right and it's just the temperature. But the smoke seems excessive, compared to other cars I own / have owned. But then again a 3rd gen RX-7 is quite unique.

I did have the cooling system pressure tested end of last summer and it was fine. I have also checked for bubbles and saw none.

I've driven it maybe 2 or 3 times since last summer, storing for the winter. I have started it 8 or so times through the winter though just to let it run a bit.

So, who knows, maybe it will clear up in the summer.

If it's excess fuel, though, any idea what could cause it?

fpr, bad coolant temp sensor. leaky injector. but who knows i say it is prob ok if it gets better when you drive it. glwi

What's FPR?

Definitely fine when I'm driving, just chokes me to death if I let it idle and hang out next to it!

It sounds like you are running too rich. If it's a sharp sufficating smell, that's what it is.
Your discription in the original post only mentioned a catback. Do you still have the precat and stock cat? If so, you are skating on very thin ice right now.

By the way, FPR=Fuel Pressure Regulator

I do still have the stock cat and pre-cat.

Why am I skating on thin ice? I thought if I DITCHED my pre-cat and replaced with a downpipe I would be skating on thin ice?

?