Will a bad fuel injector cause the exaust to blow heavy white smoke and smell like gas?

Tiny
MICHAELS2000
  • 2000 NISSAN MAXIMA
  • 230 MILES

I start my car and it dont smoke real bad, but after a few minutes it gets smokier, if I step on gas it blows heavy white smoke out and leaves a puddle of gas by tail pipe.I also get a po300 code. New plugs and all coils checked also. All in all its not drivable cause theres so much smoke and gas goes down real fast.

I just pulled all the plugs out and all are black carboned except for cylinder 6 which was clean and wet with gas the others were also dry.I checked for the antifreeze going down and no change and the exhaust doesn't smell like its burning coolant.I found puddle thought it was water also till I put finger in it and smelled it, was gas :(

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Saturday, March 10th, 2012 AT 3:54 PM

26 Replies

Tiny
CARADIODOC
  • EXPERT
  • 28,246 POSTS

White smoke is a sign of a leaking head gasket. The coolant level should be going down too. Too much gas will cause black smoke and soot inside the end of the tail pipe.

Here is a guide to test to make sure this is the problem.

https://www.2carpros.com/articles/head-gasket-blown-test

It also sounds like you might have a fuel pressure regulator that is leaking, here is a guide for that.

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

Please let us know happens so it will help others.

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Saturday, March 10th, 2012 AT 4:06 PM
Tiny
MICHAELS2000
  • MEMBER

Oh also the oil smells real gassy too.

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Saturday, March 10th, 2012 AT 4:12 PM
Tiny
CARADIODOC
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The two observations don't really jive. Too much gas causes black smoke in the exhaust, and coolant causes white smoke.

You might try switching injector 6 with one from a different cylinder and the coil from cylinder 6 with the one from some other cylinder to see if the problem switches to one of those different cylinders. Resistance tests on coils only show if there is continuity. They don't tell if one is arcing internally from the high voltage.

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Saturday, March 10th, 2012 AT 4:47 PM
Tiny
MICHAELS2000
  • MEMBER

Ok well before the car started smoking real bad, I was getting a intermitting missfire when going down road and it would come and go for about a month. Then one day it didnt come out of it. Prior to this my cat converter was smelling real bad when I tromped on it.I also got an o2 sensor code and a cylinder 6 misfire code.I had to remove battery for a while too for winter, alternator was dead. So when I put battery back in the codes were obviously gone. But just the o2 code came back and the po300.I changed the o2 sensor that was bad and no change. Could the cat be the problem, maybe build up in it that is burning up when it warms up?This thing smokes so bad that it looks like cream coming out the back, then when you turn it off you can see smoke trickling out the tailpipe like it was liquid. Im totallt stumped.

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Saturday, March 10th, 2012 AT 6:16 PM
Tiny
CARADIODOC
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You're trying to fix the results, not the cause of the problem. A misfire, as detected by the computer, will put excessive raw fuel into the exhaust system where the catalytic converter is overwhelmed. It will overheat and smell like rotten eggs.

The oxygen sensor only reports what it sees. Changing it isn't going to solve anything. In fact, you can have an injector stuck open dumping way too much fuel, but the oxygen sensor can still read normal swings from rich to lean a couple of times per second like it's supposed to. It doesn't respond to unburned fuel, just unburned oxygen. As long as the other two cylinders on that bank are working properly, the oxygen sensor won't detect a problem.

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Saturday, March 10th, 2012 AT 7:21 PM
Tiny
MICHAELS2000
  • MEMBER

Ok that all makes sense. Then probably got a small leak in the head gasket and that is effecting the engine so the computer gets a reading that tells it to add too much fuel. That would explain why I smell gas along with the white smoke at the same time. Usually I start my car up and it dont smoke until it runs for maybe 3-5 mins. Then it gradually just gets heavier white smoke. Then if I step on it im in a smog cloud.I will have it checked for head gasket leak then. As you said if it was the fuel system it would be black smoke. Even if it was a bad coil it would still be black smoke correct?

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Sunday, March 11th, 2012 AT 4:36 PM
Tiny
CARADIODOC
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Yup. The symptoms are contradictory. When a coil or plug misfires, the unburned mixture goes into the exhaust system. The unburned fuel should be mixed with stored oxygen in the catalytic converter, and burned so you shouldn't smell anything, ... Yet.

The oxygen sensor doesn't respond to unburned gas, just unburned oxygen. The computer is constantly varying the mixture from too rich to too lean a couple of times per second, (that's where the converter gets the oxygen to store momentarily). With that misfire, it sees that oxygen all the time and figures the average mixture is too lean, so it adds fuel to correct that. The problem is no matter how much fuel it adds, there will still always be that unburned oxygen being detected. THAT's when the converter gets overwhelmed and you smell unburned gas at the tail pipe. You smell gas, but he computer sees a lean condition and tries to add more gas. That's the contradiction.

Most V-type engines, '96 and newer have oxygen sensors on each half of the engine so a misfire in one cylinder results in fuel being added to all three or four cylinders on that side. Older engines usually had one oxygen sensor. A misfire ended up with fuel being added to all cylinders.

There's two possible explanations for why the smoke occurs well after start-up. The cylinder heads and gaskets expand when they get to normal operating temperature. It could be that's when a leak shows up. It's also possible for system pressure to cause coolant to seep into a cylinder after the engine is stopped. If it's excessive, that can cause "hydro-lock". Since liquids don't compress, that fluid can stop a moving piston and cause a no-start, (no crank) condition. If, on the other hand, a valve is open when you start cranking, the liquid can be pushed into the exhaust system where it will vaporize after the exhaust system gets hot. That will take a few minutes. Some of the coolant will spray out of the tail pipe right away as a liquid. It won't smoke until it gets hot. That liquid can collect in the muffler which takes longer to get hot enough to vaporize the coolant.

One problem with my analysis is: "i checked for the antifreeze going down and no change". With the amount of smoke you're describing, you should be losing a lot of coolant. Next, "i found puddle thought it was water also till I put finger in it and smelled it, was gas". We know something is going on with cylinder number 6 but gas won't wash it clean; coolant will. A better way to tell if gas is dripping from the tail pipe is to wait and see what happens to the puddle. Water will still be there an hour later but it can easily smell like gas if there was a little in it. Gas will evaporate in a matter of minutes and leave a stain on blacktop or concrete.

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Sunday, March 11th, 2012 AT 5:13 PM
Tiny
MICHAELS2000
  • MEMBER

Ok the stain on the ground is definatly happening. Leaves a dark stain in dirt in my drivway where I reved it up a few times noticed other day after many hours. And as far as the number 6 cyl issue probably where the leak is since all the other plugs are black with carbon probably cause of increase in fuel being added, and that #6 plug being clean cause of the coolant leak. Im gonna tear it down I guess, youre input has been very helpful. Thanks alot.

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Monday, March 12th, 2012 AT 2:21 AM
Tiny
CARADIODOC
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Before taking it apart, are you familiar with the "sniffer" test? That involves drawing air from the radiator through a glass cylinder with two chambers partially filled with a special dark blue liquid. If combustion gases are present, the liquid will turn bright yellow. I'd feel better knowing for sure if the head gasket was leaking before tearing into it.

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Monday, March 12th, 2012 AT 3:28 AM
Tiny
MICHAELS2000
  • MEMBER

Nope I have never heard of that test. Yea if I can avoid it, that would be great for sure. How do I do it?

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Monday, March 12th, 2012 AT 6:35 PM
Tiny
CARADIODOC
  • EXPERT
  • 28,246 POSTS

I've been told auto parts stores that rent or borrow tools often have this one but you have to buy the liquid. One bottle will fill the tool many times over so you're wasting your money. The fluid will not work once it gets contaminated with coolant. That's why mechanics always have extra, in case they accidentally get some coolant in it.

The fluid is expensive, and I've been told it won't work if it has been frozen. For that reason you can't buy it from the tool truck guys in the winter. It would freeze during shipping. Because of the cost, you might be better off just having a mechanic do the test. Or, at least watch him do one first. It only takes a minute. You squeeze a rubber ball and release it to draw air through the two chambers of fluid. If combustion gases are present, the liquid will turn from dark blue to bright yellow. If that happens, you simply move it to fresh air and draw that through it to turn the fluid blue again. You can use the same fluid over and over until it gets contaminated.

Here's what the tool looks like:

http://www.matcotools.com/catalog/product/AC560000/COMBUSTION-LEAK-TESTER/#productCustomerReviews

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Tuesday, March 13th, 2012 AT 12:02 AM
Tiny
KSENIA
  • 2000 NISSAN MAXIMA

Engine Cooling problem
2000 Nissan Maxima 6 cyl Front Wheel Drive Automatic 110k miles

When I start my car, sometimes (not every time) there is a puff of white smoke that comes out of the exhaust. I've had a compression check done by Nissan and they say it checks out fine. They suggested a fuel injection cleaning to fix the problem. Should I be asking them to do a coolant pressure check? Or would a fuel injection cleaning ($125) fix the smoking issue?

Thank you,
Ksenia

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Monday, May 8th, 2017 AT 6:08 PM (Merged)
Tiny
LEGITIMATE007
  • EXPERT
  • 5,215 POSTS

Good call! But a fuel injection cleaning can be done by a bottle of sea foam in the gas tank ( 5dollars). Oh, sea foam is the name of a cleaner for engines. What you can request after you do your own fuel injector cleaning, is request a throttle body cleaning their could be carbon build up on your throttle plate causing your problem. But get a bottle of seafoam and follow instructions for the "gas tank" method. And let me know what happens. Then maybel we can talk tha coolant pressure check

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Monday, May 8th, 2017 AT 6:08 PM (Merged)
Tiny
MISSBAILEY
  • 1995 NISSAN MAXIMA
  • 100,000 MILES

When I start the car white smoke comes out n also while driving

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Monday, May 8th, 2017 AT 6:08 PM (Merged)
Tiny
RASMATAZ
  • MEMBER

Could be just condensation/moisture./Water burning off, is the engine getting hotter than normal

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Monday, May 8th, 2017 AT 6:08 PM (Merged)
Tiny
SMUGGS123
  • 1998 NISSAN MAXIMA

Smells problem
1998 Nissan Maxima 6 cyl Front Wheel Drive Automatic 186131 miles

i put fuel injection in my car about 2 weeks ago after that I started to smell gasoline now everytime I drive to work alot of white smoke comes out the muffler and smells like gasoline I dont kno wat the problem is can somebody help?

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Monday, May 8th, 2017 AT 6:08 PM (Merged)
Tiny
RASMATAZ
  • MEMBER

Check the engine oil if its mixed with gas if so check the injectors and fuel pressure regulator.

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Monday, May 8th, 2017 AT 6:08 PM (Merged)
Tiny
GE90777
  • 1995 NISSAN MAXIMA

1995 Nissan Maxima 6 cyl Front Wheel Drive Automatic 232000 miles

I recently acquired a 95 Maxima last April and have always noticed a sweet burning smell coming from the car after I drive it for a while. Also just recently I've started to notice occasional white smoke coming from the passenger side of the engine compartment in front of the wall behind the motor.

Also every couple weeks my coolant reseviour goes low and I have to refill it. I'm also noticing coolant on the ground sometimes. Somebody told me my heater core may be the culprit, what do you think?

The temp gauge never rises beyond the center mark when I'm driving so thank fully for now my car in not over heating but I'm worried that it will happen sooner or later with this leak.

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Monday, May 8th, 2017 AT 6:08 PM (Merged)
Tiny
ZACKMAN
  • MEMBER

That sweet smell is your antifreeze/coolant being burnt by your hot motor. It is not your heater core, if the smoke is coming from the engine compartment. If it is a very small puddle of green stuff on your driveway, it is one of the heater hoses coming into the heater core, or one into the manifold. If it is a big puddle, have someone check your water pump.

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Monday, May 8th, 2017 AT 6:08 PM (Merged)
Tiny
FOKIZED
  • 1998 NISSAN MAXIMA
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 100,555 MILES

So I had my vehicle serviced yesterday oil change radiator flush. Now I have white smoke from the exhaust, the vehicle doesn't overheat though and my service engine light came on? What could possibly be the problem?

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Monday, May 8th, 2017 AT 6:08 PM (Merged)

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