I have a 99 150 with 5.4. This morning it was -3. I let my pickup warm up for about 10 minutes drove it to the gym and it ran fine. Driving it back home and from home to work it ran REAL rough and the service engine soon light came on. Real bad vibration at about 45. It ran like normal when I drove to the auto parts store to get some HEET fuel treater over lunch hour (18 degrees out). When I started it back up it ran like crap.

I was thinking maybe bad gas or maybe some water froze in my line somewhere? I changed the PCV valve about 11 months ago. Changed the plugs about 12 months/~7000 miles ago. Changed the fuel filter about two months/~3000 miles ago. The coolant was not frozen.

I am going to go get the code read at Autozone. I will post it this evening.

 

I havent had gas go funny untill -20. What is the code?

Adrianspeeder

 

You will have to go with the code this time, to see what system is causing the problem. This makes it easy.
A long shot guess is EGR system is hanging open.

 

Well I went to Autozone. The code was missfire in cyl #6. So I figure it could be either the plug, COP, or injector. The weird thing is, is sometimes it runs just fine, then when I start it back up again it runs like crap.

I got another bottle of HEET and a bottle of the premium gumout fuel injector cleaner and put it in. It was about a 13 mile drive back home. It seemed to smooth out about halfway home and when I pulled in the driveway it was running smooth again. However the CEL is still on.

I still think the cold weather did something. Any thoughts or suggestions?

Thanks for the help

 

mine did same thing before thankgiving,CEL code showed #4 missfire,got a bottle of Chevron Techron,half tank later ran fine and ever since. Its 97 4.6 150,but all your symptoms are the same. I think I got some crap gas, and clogged an injector for a bit :

 

Since you got started trying to clear it with cleaner and the HEET, let it go it's course and see what happens.
Don't load up too much on gas additives because it will bring on other problems that gets mixed in with what you are trying to solve and causes confusion.
Have the codes read again then cleared. Always clear the codes to be able to tell if what you did had any effect or caused a different code.
There is a plug boot , coil or injector dirt most likely causing the problem if it is intermittant.
Also to say an engine runs rough is a specific discription.
To say one cylinder causes an engine to 'miss' is another.
It is important to seperate the two.
A single cylinder miss usually can be heard as a single seperate sound in the exhaust pipe when listened for.
Good luck.

 

If I disconnect the negative battery terminal will that clear the codes?

I would think if 7 of the 8 cylinders were firing correctly that would make the engine run a bit rough. The idle isn't smooth. I have apply alot of accelorator to overcome the roughness and hesitation when I try to accelerate. The engine sorta acts like it does when it runs out of gas. It looses power and then suddenly gets it back.

I will wait a few days and see what happens. Then I think the next thing to do like you say is to check the plug, wire, and the COP.

 

Take the five mins and check the plug is still tight. (don't over tighten)

 

Well it ran fine to and from the rec center this morning. When I started it up to go to work it was running rough and missing again. It shudders when I press on the gas and looses power.

Which cylinder is #6?

 

Well i have just had a similar problem, Just delt with the hole Blown plug incident and ended up pulling the engine down and yanking both heads, Finally rebuilt the engine tuesday with all the nice new inserts and all new plugs and COPs. Ran fan then suddenly when it was tab bit nipply siting in trafic last night start doing the same thing. Started up this morning and still rough was driving to work and got on the loud button afew times and right when pulling in seems like it started smoothing out. I am guessing probally gas or the injector since i am sure greese or some junk got in the injectors when i had the intake and heads off the engine. Will get some cleaner tonight. Most easiest thing to do that i used to do with my COP's is read the code and move the problem.

Living in Cali truck didnt like puddles too much so i kept an extra COP in the back, when i would get something we would read the code for CYL 6 or so and move swap the COP with a diffrent CYL and see if the problem moves to that other CYL same thing with the spark plugs. Also may be very wise just to buy a book for the truck comes in handy for misc. stuff especially CYL ID's
But for now heres my attempt at showing you.

1| |8
2| |7
3| |6
4| ___|5
FRONT

 

Pretty sure #4 is passenger side left, so that would make #1 Pass side front, and #6 would be second from front, on drivers side. I will check the book tonigh.

4-8
3-7
2-6
1-5
FRONT

 

Cylinder count looking at the motor from the front.
First left cylinder is #1.
Counting to the rear 2,3,4 then over to the right side front 5,6,7,8 is rear most cylinder.
Your code would have to be a code P0306 for a missfire detection on cylinder 6.
Get in there and do all the inspection and fixes and not fool around with piece meal work.
All there is is a plug, boot and coil.
Not trying to be a hard a** but to me it's not worth the fooling around and the time expended to keep going back any more than need be.
Since the problem seems to be intermittant in nature I would say it is not a plug unless the porcelain is cracked and or the boot has a problem.
Could be that more than one problem exists.
The reason I say not to load up the fuel with a lot of additives is that it changes the fuel to much and is detected by the OX sensors. This can bring other codes into the confusion.
Look at the thread where some one tried to use E85 fuel and the problems it brought on until the fuel was diluted enough with regular gas.
Good luck.

 

Well I took off the coil pack thingamajig. I took out the sparkplug to look at it. The plug didn't seem like it was very tight as it didn't take much to loosen it at all. I looked at the rubber boot it was not cracked and did not appear damaged. The porcelain on the plug was not cracked nor did the electrode look damaged, but I didn't check the gap.

It was getting dark and was pretty cold so I quit for tonight. I will get a torque wrench tomorrow so I make sure I put the plug in right.

I will search for the correct torque for the plug.

Maybe the coil pack is bad?

 

Swap #6 COP for #2 and see if the code changes.

 

Well I swapped the COP's on #5 and 6. I had a new spark plug lying around so I put it in #6 also. I also disconnected the battery for at least five minutes.

I started it back up and it ran fine for a while, then I stopped at a stoplight and it was missing, surging, bucking, hesitating etc. I drove it for 11 miles total. However the service engine soon light did not come back on.

I'm guessing it's not the plug since it's still doing the same thing. My guess is the COP since I switched them and nothing changed.

I did a search last night and most of the problems seemed related to the COP. If it wasn't that then the problem was much worse and much expensive.

Any more advice or suggestions? Thanks in advance.