i just have a question, what stuff should i do to get rid of the carbon in my 4.9l with 127,000miles. my engine is missing possibly cause of carbon build up or a bad valve my mechanic says. should i use higher grade gas? v-power? ive done sea foam before like 2 months ago.

 

It takes a long time for carbon to build in the combustion chambers; it'll take a long time as well to get rid of it. If SeaFoam gave a positive result, then continue with it until the symptoms go away. Unless a plug is carbon-fouled, carbon itself will not cause a misfire, but a burned valve certainly will.

A bad valve, almost always an exhaust valve, can be heard at the tailpipe; run the engine at idle with the tranny in drive and listen for an anomaly in the sound of the exhaust....usually a muffled "Pffft" sound as the combustion pressure leaks by the valve.

The way to be sure is to run a compression check on the engine to see what's happening.

 

You may want to try lucas fuel treatment. I have used it for years in my old jeep with good results.

 

I am a huge proponent of hitting the loud pedal and topping out the first two gears. Just watch it all pour out the exhaust.

 

here is from what i posted about my engine missing. forum in the 87-96 f150 thread




i have replaced the the spark plugs with autolite platinums. use a thread chaser to clean threads. and used a light to look into cylinders. the only cylinder that cought my eye is 5 it looked like an abrasive stripe going across the cylinder.. ill have to look at it some day closer. but here are some videos of my truck to see if you guys can hear what might be wrong.

this is just close up of exhause, u can hear a little poping sound.
http://s77.photobucket.com/albums/j7...t=MOV03037.flv

here is a video of me driving around. you can only hear when i slow down to turn corners. juat the poping and a lot of wind. sry second video is long.

http://s77.photobucket.com/albums/j7...t=MOV03038.flv


it almost sounds like a straight piped chevy with no cats.






and also my mechanic handed me the spark plug that i had put in their and he said it is pretty much shot(im guessing carbon build up) and the one he put in was black also. so i might end up buying a set to replace every other day till it gets a lil better. and some1 told me to do a compression test on cyl5 cause cyl6 is at 140. but if 5 is the same i heard that it might be a bad valve. or could it posibly be a bent rod? and if it is a bent rod how can i tell?

 

i was listening to my exhaust now and it sounds like a poping noise inside of a tin can. if i have alot of carbon build up that is fouling the plug, if i started running cleaner through it dont you think i would have seen a difference in pick up and speed. right now and before i started running cleaner through the gas i could only run my truck in 3rd gear if im going about 35-45 mph otherwise in 4th and 5th the shifter will shake really bad. and when im on the highway i can put my truck in 5th gear (65mph). now is their another way to tell if their might be a bent rod. im not sure but if it is bent and i keep on driving the truck, can i throw the rod right out the side?

 

run seafoam through a vacuum hose on your upper intake.

 

the thing is ive ran sea foam through it twice. onece in like march. and then like a month ago.

 

well i was looking at my intake and seen that the #6 cyl had wet oil around it and all the other cyl's didnt have any oil around them. i sparayed brake cleaner around gasket it didnt die but im guessing leak is on the bottom. but im guessing it is the intake gasket.
it sounds like a tin can when my truck is idleing and im by exhaust listening to it. i know that if the intake is bad that it would have like no power and i had went through 1/4 tank in like 30 miles



here is the deal, i was at a stop light and next to me was a newer body style s10 loaded down with a sofa and a bunch of chairs and stuff(back sagging) so i tried to race him. i took off slow then floored it and yeah the s10 passed me up. i had it floored in 1st,2nd, and 3rd. now power at all.
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but seriously though there's some truth to that... I've driven many worn vehicles over the years and find after driving the snot out of them for the first two months they seem to clear up and perform better. Just my .02