I realize this has been talked about a lot, but after reading the first 6 pages of threads after searching for "white smoke startup" and not finding much similar to my situation, I decided to make a new post.

This year I started noticing that the truck would puff a lot of white/blue smoke when I started it up after it sat overnight or for long periods of time. I use the truck for towing/hauling and not daily driver use so some times it sits for several weeks.

I've noticed that if the temperatures are fairly warm, say above 65-70F, the truck will only smoke, but when I took it on a trip Labor Day weekend it got down into the 40's overnight and when I started it the next morning it missed on one cylinder for about a minute, in addition to smoking. Today I pulled both valve cover connectors and all of the GP's were between 0.6 and 0.9 ohms. The GPR was replaced within the last 2 years or so, so I don't think that would be it either.

Once the truck warms up, it does not smoke or miss at all, and fuel mileage has not changed that I've noticed. Engine has about 110k miles on it, along with a HPX line and RiffRaff Frx.

 

Even though the gpr was replaced can you put a volt meter on it just to make sure you are getting voltage on both large posts when the key is on?

 

I can try that next. I do notice when I turn the key on I see the volt meter on the dash drop down for a while then come back up to normal level, I assume when they go off.

 

Put the multimeter on the truck yesterday, and when I turned the key on, I got 10.9 volts on the glowplug side of the GPR. Battery voltage when I turned the key off was 12.45 volts, so it looks like the glowplugs are pulling the battern down when I key-on.

 

https://www.ford-trucks.com/forums/1...ke-help-2.html

 

This cold miss is a classic sign of an injector sticking.

As for the smoke, what tune are you starting on? My truck will billow white smoke if started on anything other the the stock tune.

 

I usually start the truck up on the 80 econo or 60hp Towing tune. I hadn't thought of switching it back to stock on startup, i may try that and see what it does.

About the MAT sensor link, I don't have an account on that website so I can't see it.

 

Hey guys, I realize there are plenty of reasons the 7.3 might suddenly displaythe symptoms I've listed:

White smoke
rough idle
engine missing while driving

These engines are great when everything is going right but sometimes some of those sensors start sending info to the computer that it doesn't like. Sometimes it's caused by pressure losses, oil leaks, turbo problems, etc.

But sometimes...it's as simple as a faulty sensor. So this is what I want to share with everyone. Last week I started having these symptoms so I started scouring the forums seeking answers. I saw many, many guys with the same symptoms but nobody seemed to have a simple answer.

Many of the troubleshooting methods suggested leaky o-rings on the injectors, or faulty injectors. Before pulling the valve covers I decided just to snoop around the motor a bit and just for fun I disconnected the MAT sensor. To my surprise...no more white smoke! It still ran a little rough, but the smoke was completely gone. I plugged the sensor back in...pooof, white smoke everywhere...unplugged it again...smoke gone.

I jumped on he computer, ordered up a new MAT sensor off Ebay for $10 (plus shipping) and drove the truck for a day with the sensor unplugged. I imagine I was in a default setting. The sensor arrived today and this evening I installed it. The installation was about as easy as it gets.

the MAT is the Manifold Air Temperature Sensor. When it goes bad you might pull codes:
P1118 Manifold air temp sensor out of range low
P1119 Manifold air temp sensor out of range high

In my case, I didn't have either of these codes so I had no warning. When I unplugged the sensor, the computer showed P1119 until it was replaced.

Purpose-The MAT relays the temperature of the incoming air to the ECM.
How it works-The ECM sensor sends out a 5 volt reference signal to the MAT sensor. The ECM will then read the resistance it receives from the MAT. If the temperature is low it will have a high reading. If the temperature is high it will receive low reading.

THE MAT SENSOR SENDS INFORMATION WHICH EFFECTS FUEL DELIVERY.

The MAT sensor is located directly in the center of the Y pipe. It is located directly behind the HPOP.

I hope this info saves one of you the hours of frustration that many of us have suffered through.

Of course it is very possible this is not your problem, however it will take you all of 30 seconds to check out, so it's worth a shot!

***EDIT*** The MAT sensor I ordered was Delphi Part Number TS10098-11B1

Sensors' located in the front/bottom of the spider assy, under the "green" plug.

 

I messed around with the truck a bit yesterday. It was about 75* when I started it up so it wasnt really cold. I started it up in the econo tune, and it started smoking pretty much right away, so I switched it to the stock tune and within about 30-45 seconds the smoke cleared up.

It did not miss at all, but when I held the engine speed around 1000rpm I thought I could feel a slight shake in the engine like maybe one of the injectors is weak. At idle it runs pretty smoothly though.

I also pulled the oil fill cap off to check for blowby, and I did not see any vapor coming out of the tube and did not feel any air movement so that rules out a compression issue. I think i'm going to look at scan tools so I can hook up and run the cylinder contribution test.