bet its the coil, they can do weird things when they die

 

Just got an OBD II reader today and gonna hook it up to find out what kind of codes are spittin out. Was reading that the rapid flashing of the MIL means theres a misfire that can cause damage to the catalytic converter... is this correct?

 

Got the reader and it is pulling code: P0300 Random Misfire...
:bang: I'm truly aggrevated now. The shop was supposed to have cleared that up by replacing the plugs and sensor and it does not list which cylinder in specific is misfiring...

How do I check if it is a coil issue?

 

not really sure there is a way to test the coil, its kinda of a swap it with a known working one and hope it works lol

 

pull the plugs out and see if they're cracked or black or something, and check resistance on your plug wires.

your car is probably due for a tune up anyways

 

Troubleshooting ignition...here we go.

You say it idles rough. Here's my way of checking it. Easier if you have two sets of plug wires, but it will work if you have a buddy with a Focus who can help you out. Start your car. Wait for the idle to get lumpy and rough, and gently remove the #1 plug wire. If idle quality changes, reconnect the plug wire, wait for idle to stabilize, and repeat the process all the way down the line until you pull a plug wire and nothing changes. At that point, you've identified which cylinder isn't getting spark or has the bad spark plug. Turn the car off. If you have a spare set of wires, connect a replacement wire to the coil pack and plug it in to the spark plug itself. Start the car. If idle quality still sucks, shut the car off. Wait for the cyliner head to cool a bit, then remove the plug. Check EVERYTHING, from the electrode, to the gap, all the way out to the porcelain insulation on the plug end of the spark plug. If you see anything unusual, replace the plug. If not, move the plug to another cylinder and reconnect the wires. See if the problem followed the plug (example, say the #3 cylinder isn't firing. You try a new wire, idle quality still sucks. Pull the plug, nothing visibly wrong. So you pull the #2 plug, inspect it, and install the #2 plug into the #3 cylinder, and install the former #3 plug into the #2 cylinder. Plug the wires back in). Start the car, wait for idle to get poopy again. Disconnect the #3 plug wire, and see if it changes. If it doesn't change, pull the #2 plug wire. If it doesn't change, 99% chance the problem is a bad plug. If you have replaced the wire, moved the plug, and idle still sucks and #3 still isn't firing, odds are it's a coil pack. Check the pigtail harness that plugs into the front of the pack. If it is cracked, worn, brittle, or otherwise damaged, repair it if you can. If nothing is visibly wrong with the harness, see if you can borrow another coil pack from a buddy and test it out on your car. If the problem is corrected, replace the pack.

I have some experience with this, since my old FoFo had random misfire issues multiple times during its lifespan. Some of those were from water intrusion from engine washes. Some were from oil intrusion from a bad valve cover gasket. One was from a bad harness. One was from a nearly invisible crack on the spark plug insulator that I caused when I changed my plugs.

 

BUMP!
Update... I took it back in and found there were two loose connections on bank 4. The car is running better and had a compression test done and all are above 190. MIL came on this morning on the highway going 40mph and when I went to shift into 4th gear from 3rd it starting stuttering and vibrating very roughly. It finally smoothed out after 5 minutes and the code is P0304.. Cylinder 4 misfire. I have the freeze frame data but heck if I understand it. Help, just want my spunky focus back!

 

Did you pull the spark plugs to look at them? Get a spark plug gap tool. The plugs should be gapped to 0.05

Your car is a 2003 with 97,000 miles.... it needs a tune up. This usually involves a few filters here and there, and SPARK PLUGS. Also might be a good idea to check the coil packs on your plugs. I don't know how to check them though, my Focus was a zetec and didn't have coil on plug.

 

Did you pull the spark plugs to look at them? Get a spark plug gap tool. The plugs should be gapped to 0.05

QUOTE]
pretty sure teh gap has to be bigger than that. that is like nonexistant.
i think its around .55

 

The spark plugs and boots were just replaced 2 weeks ago. And a supposed tune-up was performed. Its not the plugs or injectors, but I am in the process of getting the coils checked out particularly on cylinder 4...

 

No. .55 would be over 1/2" worth of gap...

Ideally, for a stock, non-capacitive discharge ignition system, the gap should be made to right around 0.050"-0.055". You might be able to get away with 0.060", but that might introduce the occasional misfire. One common technique is to gap to 0.065", then reduce the gap until no misfires are present.

 

Ok, now i'm about to lose all faith in my focus. Took it twice to thwe shop for same problem... was fine until monday. now today round 4pm it started to shake and shutter, idle ROUGH CEL, and as I went to pass an intersection in first gear it would not accelerate- and I had the pedal to the floor! the RPMS would not rise either... i'm at a loss of words... and a loss of faith in my lil focus

 

Have you changed the coil yet?

 

not the coil... could either be the crank position sensor or the cat... gonna try the sensor replace and see if that fixes it.

 

What would cause a flapping sound in the engine area? It is present at idle and running; does not get worse or better when driving. And it is not the plugs firing, it is a flapping like rubber flapping...

 

Ok well tomorrow is the true test... I replaced the crankshaft position sensor an d now I don't have the weird flapping sound but we'll see if the 80 mile drive to/from work dislodges anymore issues!

I think my focus sometimes has more issues than TIME magazine somedays...

Wish me luck!:rock: