Help us help you. By posting the year, make, model and engine near the beginning of your help request, followed by the symptoms (no start, high idle, misfire etc.) Along with any prevalent Diagnostic Trouble Codes, aka DTCs, other forum members will be able to help you get to a solution more quickly and easily!
I have a 99 explorer ive been doing some work on.I keep getting a misfire on cylinders 3 and 4. Coil was replaced due to primary ignition dtc and the intake manifold replaced due to hairline cracks( i coudnt find using smoke test, found it using brake clean on flat parts of intake). Any suggestions anyone? Test drove and misfires are still present. I did plugs and wires a few month back, i noticed plugs have the heat marks, everywhere im reading states lean mixture advanced timing etc..... test drove this thing up a pretty decent hill and it has good power with no noticeable misses.
Istr 3 & 4 are companion cylinders on the German V6, that points back to the ignition coil. Ford use a particularly wide plug gap if there is an open in a plug lead or the plugs worn the ignition secondary voltage goes through the roof and the insulation of the coil becomes permanently damaged. The Ford V6 wasted spark coil pack is in fact 3 coils packaged in one unit. While it could be an ignition primary fault such as an open or short on the coil control wire for cylinders 3&4 the simplest way forward for the non-pro is new coil pack plugs and leads on cylinders 3 & 4.
If the discolouration you are seeing is on the spark plug insulator in on outside of spark plug it is normal
" We're trying to plug a hole in the universe, what are you doing ?. "
(Walter Bishop Fringe TV show)
I just replaced the coil a few days back with one from oreilys. I used scannerdanners method of testing spark strength with a test light and number 3 coil tower was weak. Plugs and wires were replaced about 2 months back. Yes the plugs do have discoloration, like too hot of a burn(can i run it like that or should they be replaced?). I dont have a secondary ignition probe or id do a scope test on it. Primary doesnt seem to show much. If i bring it off idle (say maybe 1100 rpm or so) you can feel the roughness, but at higher rpm it seems ok. I was chasing a air leak for a few days, thats when i replaced the intake itself. The best i could get the fuel trims was 7% bank 2 and 4% bank1(at idle) and that was after test driving it hard uphill, Which is weird because it seems to have a lot of power for having a mis on 3and4. The trims seem to drop lower with higher rpm( which seems like a air leak) but i cannot find anything. I only get smoke out the iac valve and the egr(not sure if that is normal).fuel psi is 62 and based off WOT test, fuel delivery does not seem to be my problem.
