98 Expedition, 4.6 180,000 miles. codes come up misfire #1 #3 #8. New plugs, wires, coils, injectors, exhaust manifolds, egr valve, thermostat, and tps, and pcv and hose, tried a compression test but none of my fitting will work. One thing I did notice is that the spark on all 8 cylinders is orange and not blue. If I pull the #1,3,8 plug wire off it runs worse than normal.

Last night it started popping. Not a backfire just a little poof. read codes now it's #3 #8 and bank 2 lean. I love this truck but it's kicking my ***. On a side note it ran like **** when I bought it. All the work I have done made it run better but still rough under acceleration. It was still driveable tho. Please help. I have read dozens of post with the same kinds of issues, and I have tried most suggestions. Now I'm lost. The orange spark has be baffled the most I think. I haven't read a post covering it so far.

 

You need to do the compression test. If valves are not sealing tight, then no parts you replace will make a difference.

 

Are these motors known for bad valves? I can see one bad valve or cylinder but 3 at a time?

 

What plugs are you running?

 

Auto-lite plugs. said to be direct replacements. Will a different brand make a big difference?

 

Motorcraft!

 

Look closely at the number on the coil and verify your plug wires are going to the correct plug.

 

I checked the firing order twice. Should I switch to Motorcraft plugs? Will it make a difference?

Now the other day it started popping. not quite a backfire... then the next day it ran as good as it does normally (not real good) but no popping noise and it had power again. Then tonight it started popping and when the rpm's hit 3000 it went away and ran "normal" again. I haven't been this stumped for 25 years! The bad part is I'm in too deep to sell it and also tired of putting money into it. Other than all the b.s. I do like driving it.

 

[quote=Total Gearhead;13859663]Auto-lite plugs. said to be direct replacements. ?/quote]

Are those double plats?

(A waste spark system should have double plats. Motorcraft AWSF32PP)

 

After changing ALL those parts, what specific codes are you now getting?

Out the exhaust or out the intake?

And what was the results of the compression test?

 

po301 po303 po308. it is a very slight pop noise. i would guess intake. it does not do it until you are driving. and it isnt constant. maybe every 15 to 30 seconds. My adapters will not fit to check the compression. my parts store has the same set that I have. I might have to make an adapter

 

are the cats plugged

 

They don't seem to be. It has plenty of power most of the time. I did drill an 1/8" hole just before them and didn't hear any whistle. They arnt glowing. is there another way to test them?

 

May as well "git 'er done".

 

With the engine idleing how many volts are you reading on the red w/green strip wire at each coil pack?