P0304 P0443 white smoke misfire 07 Tahoe 5.3 4x4

[Jps0039]

This one has me stumped. Have done coil pack, plugs wires, MAF l, purge valve solenoid, and fuel injectors. The best advise I’ve gotten so far is to seal out an upper end OB2 reader to check compression and graphs. And to manual test fuel pressure. I’ve recently replaced the vent valve solenoid also and TPS. Could be bad CAT or MAP or fuel pressure regulator. Any and all advise appreciated I’m at my witts end. Live in Lee county AL if anyone lives close by. 07 Chevy Tahoe 5.3 4x4


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[Jps0039]

Should also mention the misfire is bad at idle, shifts rough. Does better once up to speed blows thick white smoke smells like gasoline not oil.


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[OR VietVet]

Gasoline will not blow out a "white" smoke. Thick white smoke indicates coolant in the exhaust therefore pointing to the likelihood of a damaged/blown head gasket. I am very surprised that with all this misfire problem that you have not done a compression test yet. That test should pinpoint the cylinder(s) involved and the source of the misfire. What does the oil look like when you remove the dipstick? how about the oil fill cap when you remove? Coolant tank inside? Using coolant? This will also effect the catalytic converters and the oxygen sensors. Do you have any codes?

 

[exp500]

Put Noid lights on your injectors and watch..... My guess is you have a pinched wire grounding an injector or many injectors.

 

[Jps0039]

Thanks. Pops and I are going to try this next got an old one from my grandpa hopefully she still works. Know anything about overriding the AFM read that it’s potentially stuck on four cylinders


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[Jps0039]

@PNW thanks for the response. Yeah I’m self taught and still learning. Never done compression test before but will give it a go. The Coolant levels are steady which lead us to rule out the head gasket. Oil is being burnt faster than normal.


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[OR VietVet]

Oil smoke is blue, coolant smoke is white and too rich fuel condition is black. If there is another form of "thick white smoke" I need to be taught about it.

 

[exp500]

PNW Vietvet- my education on white smoke came from a mitsu I bought way cheap. Owner said all he did was change spark plugs and it wouldnt run. I got it started, filled the whole shop with white smoke before I got it shut down, about 15 seconds. Scared the bejeebers outta me (seen a few vapor clouds light off in my past). Good thing air compressor didn't start up.Took another 10 minutes to air out shop so eyes didn't water. Found Injection harness pinched flat under intake manifold grounding injectors for full flow. Thats why I suggested noid light. Funny how much smoke will come out exhaust with an engine runnin. Also- you're about old enough to remember "Bug Trucks" aren't ya?

 

[Jps0039]

My dad corrected me and said thick ***** smoke would be like a sceeter truck. This is just regular white smoke. I will inspect the lines further and make sure there’s not a grounding issue. Thank all y’all for the responses. I will be relived once this is resolved until the next project.-JPS


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[OR VietVet]

Oh yea, I know about the "killing bugs" smoke screens out the tail pipe. Hope you find the problem at the injector wiring.

 

[Jps0039]

Alright so after second analysis it appears that the P0443 is pointing us right to the purge solenoid under the hood or the PCM. After checking with multi meter and checking vacuum when plugged in and unplugged all seems to be ok with the new solenoid. At another road block.


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[OR VietVet]

What about the other valve at the rear near the spare tire?

 

[Jps0039]

Replaced the vent valve under the car about 6 months ago because of pressure building up in gas tank. No codes pointing towards it and gas tank isn’t pressurized ,it seems fine. Charcoal canister could be bad and clogged I guess. When I crank it almost cranks faster than normal and it stutters at idol. I cleared codes took for a test drive after checking wiring harness all looks in good order. I might try disconnecting hose from canister while running to see what I get


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[Jps0039]

Welp dad offered to slap another purge solenoid it it to rule it out once and for all. No dice. Guess I’m going to focus on electric moving forward. This is a bear


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[cam3439]

Check your old purge valve to verify it isn’t clogged. Sometimes when a canister fails, it’ll shoot carbon pellets through the lines, which can end up at the valve and clog it. Pellets keep clogging the purge valve until you clear the lines of those pellets. When you disconnect the line, shake it. If you hear rattling, then there are pellets in the line. You can also inspect the inside of the purge valve for carbon pellets. I had to disconnect all lines at their connections and blow them out to clear the pellets when this occurred on my truck.

As for cylinder 4 issue, you can also rent a coolant pressure test kit from like Autozone to see if your coolant system can hold pressure. If you have leak down, then it confirms a leak. Pull the spark plug from cylinder 4 to see if it’s wet or cleaned off compared to your other plugs.

Note that if you have a coolant leak in a cylinder during the test, you’ll want to pull the plugs before cranking it over, or else you get hydro-locked (best case) or bend a valve or connecting rod if the leak is significant enough.

 

[Jps0039]

Taking it to my buddies shop on Monday he has all the tools in the world I could need for better diagnostics. I’m beginning to lean towards crankshaft position sensor after a little more research. Gonna preform a smoke test and compression test for sure. I threw the old purge valve solenoid out by mistake like a big dummy. So vaccine leak, spliced wire, or bad pcm or crankshaft position sensor. Guess we will see


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[Fless]

Taking it to my buddies shop on Monday he has all the tools in the world I could need for better diagnostics. I’m beginning to lean towards crankshaft position sensor after a little more research. Gonna preform a smoke test and compression test for sure. I threw the old purge valve solenoid out by mistake like a big dummy. So vaccine leak, spliced wire, or bad pcm or crankshaft position sensor. Guess we will see


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"vaccine" leak LOL get that under control!

 

[Jps0039]

Anyone have anything similar before?


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[OR VietVet]

I get that same smoke after a cold start as it warms up. That is normal. When driving the heat builds in the exhaust. When shut off engine the heat will cause condensation in the exhaust system while cooling down. Then that condensation gets heated up on a restart and causes smoke like this. That is grey smoke and a byproduct of this process. When you have coolant burning white smoke it will look thick, like cotton candy. I see no problems with this smoke.

I would guess that if there is a problem in the evap system this same smoke could differ than what you are used to seeing and of course that needs to be addressed.

 

[Jps0039]

Problem is it spits this consistently at idle and even heavy when rolling down the road


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