what the hell is wrong with my car?

[myfirstmazda]

ok, I posted about this a while back, and didn't get much help, but here goes... my car blows white smoke on a cold start. It's not oil or coolant, it's unburned fuel. I changed the o2 sensor thinking that was the problem, but it hasn't made a difference. It only happens on a cold start, when the engine has been sitting overnight and the temps get below about 60 or so. It blows white for maybe 30 seconds or so, but it's a hell of a cloud, and it's embarrassing, not to mention it's hurting my mileage. I know what oil smells like, I know what coolant smells like, this is neither of those. If you go out and start your car in the middle of winter and stand by the exhaust, that's what it smells like, only a lot of it. Been fine through the summer, but now it's starting to cool off again, and I don't want it doing this all winter long...


any help solving this problem will be GREATLY appreciated. This is the only real problem with this car right now, and I want it fixed. Thank you.

[Ryan]

I'm sorry, but that is very likely coolant.

the other thing is, it might be water, if you only drive your car about 2 minutes before parking it again. Short commute?

[h3xt0r]

I know your pain...Well sort of... My F350 PowerStroke did that on start up but thats because it was a diesel...and it looked cool for a truck..

Anyhow. Has your car felt likes its lost power? If you rev it up when its doing that does more come out or does it stop? Have you done anything to your engine recently? How many miles on the engine? Does the smoke have a light blue tint to it or just white?

My best guess would be oil or coolant as Ryan stated. However, if you're positive it is neither than...well...what? Haha. If it was fuel...At that volume, i'd imagine the car would be really...reeeallly jumpy from lack of fuel. However, if it is indeed the fuel coming out it means that 1.) ECU is sending WAY to much fuel 2.) Spark plugs/wires are old and worn perhaps? But its odd that it only happens when its cold. Perhaps an electrical issue or something?

[myfirstmazda]

I'm sorry, but that is very likely coolant.

the other thing is, it might be water, if you only drive your car about 2 minutes before parking it again. Short commute?

hasn't lost any coolant in months, but my commute is about 4 or 5 miles one way. makes no difference if I drive it all day and park it.

I know your pain...Well sort of... My F350 PowerStroke did that on start up but thats because it was a diesel...and it looked cool for a truck..

Anyhow. Has your car felt likes its lost power? If you rev it up when its doing that does more come out or does it stop? Have you done anything to your engine recently? How many miles on the engine? Does the smoke have a light blue tint to it or just white?

My best guess would be oil or coolant as Ryan stated. However, if you're positive it is neither than...well...what? Haha. If it was fuel...At that volume, i'd imagine the car would be really...reeeallly jumpy from lack of fuel. However, if it is indeed the fuel coming out it means that 1.) ECU is sending WAY to much fuel 2.) Spark plugs/wires are old and worn perhaps? But its odd that it only happens when its cold. Perhaps an electrical issue or something?

power's about the same as always, but that's not quite where it should be either. I've never revved it up while it was doing it. haven't done anything to it recently, but it has 200,000 miles on it. haven't noticed any blue, I'm not using oil at any rate worth worrying about, just a little leakage. plugs and wires could stand to be done, maybe I'll do those. seriously, I know it sounds unlikely, but this HAS to be fuel, there's nothing else it COULD be. that's what's confusing the hell out of me. if it was using coolant, it would be a lot easier to figure out. that's why I'm asking for help. I'm wondering if some sensor is sending bad information to the computer or something. but, again, just when it's stone cold? I don't get it.

[nos92mx3]

Hmmmmm, have you pulled and tested your intake air temp sensor/ cooltant temp sensor?
Test those against the FSM specs and see what it says.

[myfirstmazda]

no, I haven't. how do you do that?

[Dark_Rider2k3]

have you tried pulling codes too? My water temp. sensor was bad in mine and I never saw the check engine light came on. But there was a code.

[myfirstmazda]

I did several months ago, that's why I changed the o2 sensor. haven't checked since then. maybe I better.

[Pure-Powder]

Blown Head G asket!

[myfirstmazda]

everyone seems to think it's a head gasket, but i'm just confused about why, if it was, would it only do it when it's cold? and only for a minute or so? I'm also confused because I haven't been seeing the coolant level going down AT ALL. could it really be a head gasket? I might just change it anyway, because that's where my oil leak is coming from, but I have trouble beleiving that's where the problem is. oh, and yes, it does "jerk" or "jiggle" if I drive it cold while it's doing that. if I rev it up, it just gets worse, and then it adds oil smoke into it. please help me get this solved.

[nos92mx3]

The coolant and air intake sensors are just resistance based at certain temperatures.
Check the manual on the home page as to what they should be, all youll need is a multimeter to test. Since your having the problem cold i would just test them in car, if they are out of spec, replace.

[myfirstmazda]

I pulled a code 17 today...

[myfirstmazda]

I tested my thermosensors this morning... got no reading out of the coolant thermosensor, but when I unplugged it I started the car to see if it made a difference, and it threw a code 9, so it must be doing something... my understanding is that code 17 is the "feedback system". somebody explain to me what the feedback system is, and how to check it.

-edit- I may have had my meter on the wrong setting, I'll check it again.

[wytbishop]

Code 17 on the B6 is related to the O2 sensor. Could be a bad sensor, but could also be a break in the wire between the sensor and the ECU. Could be clogged or sticky. Read this and do everything it says in there. Then check codes again.

http://www.mx-3.com/manuals/showimg.php ... F1-092.gif" onclick="window.open(this.href);return false;

[myfirstmazda]

o2 sensor's brand new, I'm gonna disconnect the battery to clear the codes and try it again. the coolant thermosensor's reading right, I must have had the meter on the wrong setting.

-edit- there's only the one o2 sensor, right? right there in the exhaust manifold?