several symptoms, no clue

[myfirstmazda]

it's a 93 mx3 b6me, 5spd, 197,5xx miles. if you let the car idle for a minute before shutting it off, it will smoke like hell the next time it's started cold. it's white smoke, but it's not oil or coolant, it's incomplete combustion. it won't do it if you shut it off right away, but if you sit and idle at all, it will do it. it's like it's idling too rich or something, but it passed emissions just fine. if it was rich, wouldn't it take longer to warm up? it actually warms up pretty quick. also, there is a "surging" under acceleration, like the power comes and goes. it was trying to stall on me last week, and it did stall once or twice, but when I actually shut it off with the key and restarted it, it ran just like always. no stalling since. I don't get it.

[Ryan]

well, running rich is black smoke.
burning oil is blueish
and coolant/really cold days is white.

So unless its really cold, which I don't think it is anywhere (that you can drive) on the planet right now, I'd say its coolant.

Check your coolant resevoir, see if its brackish/oily, or low.

Also, these cars run rich when cold. Its designed that way, thats why we have thermosensors. The purpose is likely both for ignition and heating purposes, but I'm not a Mazda engineer.



Concerning your problem, have you tried a tune up? filters, plugs, wires, cap and rotor, set ignition timing/idle speed, maybe a good 'ol can of seafoam...

[MX-3zoom]

Dont get upset your not alone, my car is doing the same thing. Its done this since a week after i bought it. I've changed the spark plugs/wire. Cleaned the TB. Just now seafoamed oil(then changed oil),gas,Intake(boy did alot of smoke come out). Ran fine for the day, next day back to bad idle,surging,CEL on/off and now it dies sometimes...I think im just going to take mine to the shop, so they can find the problem instead of me guessing.

[Ryan]

MX-3zoom, your issue sounds like a vac leak.

[myfirstmazda]

maybe it's time for a can of seafoam... I'm not losing oil or coolant. you know how a fuel injected engine smells on a cold morning? smells just like that, only a buttload of it.

[ryant26]

So unless its really cold, which I don't think it is anywhere (that you can drive) on the planet right now, I'd say its coolant.

I live in Calgary Alberta, its snowing right now. lol

[myfirstmazda]

you know what's funny? about 3 days ago it snowed here (slc,utah), the next day it was 70 degrees.

[MX-3zoom]

Ill look again...unless the last owner put hoses in wrong spot or something. Wanna fix it, starting to tick me off, be cruisen then all the sudden my car is jerkin like its about to die......Miss my Gs never had problems, alomost finished with 'er thou

[myfirstmazda]

did the seafoam today, seems like it maybe has a little more power, but still has the surging/flat spots, about the same... let me point out that this surging is not at idle, it's under acceleration, most noticeable in 2nd and 3rd gears. it seems to clear up around 3500 or so, but not always. as far as the smoky starts, what about this: weak spark at idle causing incomplete combustion, would that be a possibility, or would that get worse under load?

[nos92mx3]

Sounds like a bad o2 sensor/exhaust leak pre o2, our o2's control fueling below 4k rpms, after that the ecu takes over, hows the fuel economy?

[umcamara]

Sounds like a bad o2 sensor/exhaust leak pre o2, our o2's control fueling below 4k rpms, after that the ecu takes over, hows the fuel economy?

What makes you say that Open-Loop happens at 4000 RPM's? I don't think it's that simple. Take a look at this thread I'm looking for help with, if you have time:

Click Here

[nos92mx3]

On my wideband o2 , no matter what load below roughly 4k rpms the afr stays the same vs 4500+ both at part and WOT.
Dosent matter if i go up a steep hill in 4th or second below 4k its the same afr, once over 4k though the afr drops.
Alot of miata guys have problems running aftermarket turbo kits and its why they use an o2 clamp

[myfirstmazda]

I'm getting about 30 mpg, as long as I keep it under about 70 or so (the 3500 mark or so). and I just finished fixing my leaky exhaust, cracked radiator, and leaky valve cover gasket, so it's not an exhaust leak, and I've got a pretty good eye on my coolant and oil.

[myfirstmazda]

just a bump. anybody think of anything new?

[MX-3zoom]

Dont get upset your not alone, my car is doing the same thing. Its done this since a week after i bought it. I've changed the spark plugs/wire. Cleaned the TB. Just now seafoamed oil(then changed oil),gas,Intake(boy did alot of smoke come out). Ran fine for the day, next day back to bad idle,surging,CEL on/off and now it dies sometimes...I think im just going to take mine to the shop, so they can find the problem instead of me guessing.

My mechanic wont be able to get me in for while, Tomorrow is my day off and i would like to tackle the problem...It died going around a corner lol. Found there is no gasket on the exhaust down pipe. I'm due for an oil change and was wondering if there was other things to replace(o2 sen. Gasket, more?) to help with the prolems, Thanks

myfirstmazda- did you find a cure?