okay lets start off by stating i am no qualified mechanic, but iv done research. I own an '06 5.4l v8 with 60k miles, new AirAid Intake, and a flowmaster exhaust. I recently replaced the fuel filter in an attempt to fix the problem, but nothing.

my truck started acting up a while back, and from what i read it seems to be misfiring (again its just my assumption). My cousin is a mechanic and he wants to charge $250 for the spark plug change + $40 per coil that has to be changed and his guess is that 2 new coils are needed.

So i thought about it and figured, why cant I do it and save some money for a tuner? I can either borrow the tool from my cousin or buy it myself, and do it on a weekend. I would also enjoy digging a lil deeper into my truck, so I can learn some more. So my questions come down to this.

1. Is there a way to check if i do need new plugs or coils?
2. Is there a way i can check if a coil is working?
3. Can i find out which cylinder is misfiring somehow?
4. What would you recommend?

Thanks for ur help!

 

im also looking at getting a tuner soon neway. would it be beneficial to get it before i fix it so i know what the problem is?

 

If you need plugs (at 60K you shouldn't) or coils, you'll get misfire codes on the computer. Bring it to a mechanic an have them run a code scan.

If there's a misfire, it will show up in the diagnostics.

Hard to tell what's going on without a better description of the problem.

He shoudn't be "guessing" how many bad coils there are, the computer should tell him.

 

If you have a misfire at 60k, you might as well change all of the plugs. If it is a bad coil you should be able to find out which one is bad by swapping it with one that isn't setting a misfire code. If the code follows the coil, then it is a coil. If the code doesn't then it is most likely just a plug but you might want to check compression. My truck had 52k on it when I changed plugs due to misfires and they were WORN out.

 

if it is compression? how would i know or how would i check that?

I am also going to order the tuner so hopefully it will tell me what cylinder"s" if any are misfiring

 

if you have an advance auto store nearby take it there they will pull codes for free.

 

GM has the easy way of finding a mis-fire, by using a 'monitor' to show you what cylinder is missing and how many times it is. Ford has a different way of telling you about a misfire. The PCM has to see a certain amount of mis-firings within a certain number of engine revolutions. If it sees that it will reduce power and make the check engine light flash.

Now..just because the light flashed, doesnt mean that your local auto parts store will be able to pull a code. Usually the light has to remain on in order for them to get a code. With Ford's scanner or a good ($3000+) scanner you can go into mode 6 and find 'freeze frame' data. This is basically a snap shot of all your sensor's readings when the last problem happened.

The way that I found out which cylinder was mis-firing on my truck was to look at the 'freeze frame' data, clear that data, do another run in a open parking lot and look at the data again. Every time it showed almost the same exact data when the mis-fire occurred.

But this didn't tell me which cylinder(s) were mis-firing. So I hooked up Ford's NDS scan tool, which is basically software and a cable to connect the OBD port to a laptop provided by you. With that software you can run a power balance test. A power balance test shows the RPM of the crankshaft at each cylinder firing. The NDS graphs this as dots, in the same order as the firing order, and then draws a line through the dots. About twice a second it will update a new line and leave a 'ghost' line for you to see.

Well, after a few more runs through the parking lot, I found that cylinder 2 and 5 were weak. I was losing about 40 rpm when these cylinders were suppose to fire. that means that the next cylinder in the firing order had to make up for that and they showed a spike in power when the others missed. Changed all the plugs and the coils on 2 and 5, runs like a dream now

BTW, I know that this doesn't help you unless you have access to these scanners. Lucky for me I can go to the college I went to school at and use theirs. Other than looking at live data, I don't know if you can figure out which cylinder is mis-firing. Unless you have a check engine light that stays on.

 

yea, my check engine light stays on, but it may be due to the intake/exhaust, ill take it to the advance autoparts see if they can tell me, is there neway i can get that scanner online?
thanks

 

It takes forever for codes to self clear without ever showing up. A CEL that is on will show a current code, if it isn't on there should be a stored history code. A BLINKING light is a catalyst damaging problem, usually a misfire. There should be a code, P0300-P0308. P0300=random cylinder misfire, P0301= misfire on cylinder 1 yadayadayada up to P0308= misfire on cylinder 8.

 

how exactly does the computer realize that a misfire has happened? must be some sort of feedback from the COP or it measures the inrush current to the cop to verify spark. But that being said, poor spark generated by a worn or bad plug probably won't be detected as a problem and you might have rough idol without engine code. can anyone shed some light?