Focus Help: misfire code

'00 ZX3 138k mi. with a less-than-stellar maintenance record. Started running rough with more than approx. 1/4 throttle, rough idle, died at idle once. Read the code today, only one for misfire on cyl #2.

Any known trouble spots I should look at first? My instinct is plugs and wires, since they've probably never been changed.

By the way, what part reports to the ECU that there's a misfire? Is it spark or fuel, or...?

Sounds like he timing belt is slipping.

what part reports to the ECU that there's a misfire? Is it spark or fuel, or...?

not that EZ. So the short answer is both.

Don't say that. Come on. Slipping? Will it do that, or will it break the belt or break teeth?

Come on, man, it's a holiday...

Timing belt on Fords is normally an all-or-nothing failure.

Load sensitive misfire on late model Fords is usually plugs and/or wires. The valley where the plugs are gets filled with water, leaves, rodents, etc. Not good for the plug wire boots.

Depending which engine you have, on the Zetec DOHC often the valve cover gasket leaks oil into the plug valleys. Also the plug wires where they connect to the plug can cause a misfire if it is not correctly installed on the plug. Probably a good time fpr new plugs and wires. Do a compression check when you have the plugs out.

Was the code P0302? <blockquote> P0301 through P0310 - Misfire Detection Monitor The misfire detection monitor is designed to monitor engine misfire and identify the specific cylinder in which the misfire has occurred. Misfire is defined as lack of combustion in a cylinder due to absence of spark, poor fuel metering, poor compression, or any other cause.

Ignition system Fuel injectors Running out of fuel EVAP canister purge valve Fuel pressure Evaporative emission system Base engine

The MIL will blink once per second when a misfire is detected severe enough to cause catalyst damage. If the MIL is on steady state, due to a misfire, this will indicate the threshold for emissions was exceeded and cause the vehicle to fail an inspection and maintenance tailpipe test.

I would start with checking the plug wires. A complete list of codes can be found here. Ford DTC codes

Thre are a number of things on a Focus than can cause those symptoms, but at 138K it is overdue for a timing belt if it hasn't been done. Usually though if the timing belt is the problem it just breaks on a Focus rather than slipping.

See, that's much better news. Plugs and wires I can do. I'm really trying to avoid doing a timing belt on this car before I sell it.

Thanks, y'all.

Not to put any1 down.

Broken timing belt is like,Vice grips. It is just a term that is used that every1 knows what talking about.

I see more belts slip than I see ones that brake. more often I see failed hydro tensioners, idler and water pumps.

check the belt! and dont reuse the tensioner!

iceracer wrote: Depending which engine you have, on the Zetec DOHC often the valve cover gasket leaks oil into the plug valleys.

Yep - I bet the plug valleys are full of oil.............

The less-then-stellar maintainence record is key here. I just picked up a '00 ZX3 zetec car. I had a miss in one cylinder, what apparently was low power, and terrible gas mileage. I first replaced the factory plugs and wires that had 100K miles on them . Didn't help. I trouble shooted the MAF and DPFE (EGR part). Still nothing. Finally, I pulled the brand new plugs I had put in to find cylinder #1 fouled to hell. Guess I found my misfire eh? Upon putting all of the plugs in except number 1 and attaching it to its plug wire, I was getting intermitent spark. Replaced the coil pack, voila! Car runs like a freakin' dream.

The coil pack on these cars appear to be severly stressed; they are in a high heat soak area, and attached to the motor so there is lots of vibration. Since the single coil pack does all of the work for 4 cylinders, it sees a lot of use. When poor maintainence (ie, not replacing the terrible ford wires along with the plugs at the correct intervals) causes the coil to become overworked and burn itself out in short order.

My specific scenario was running like crap below 2000rpm, a noticable misfire at idle, and a miss at highway speed (along with lack of power). The car would almost stall if I turned an accessory on (lights, or rear defroster for instance).

Sounds like a pretty similar situation, and I do have my eye on the coil pack if the plugs/wires don't do anything for me. That coil pack does look like it lives a hard life.

I don't have any accessory-induced loss like that, just a load sensitive misfire. And the engine light went out yesterday...

Parts should be getting here this afternoon, so we'll see what happens this evening.

Installed generic aftermarket plug wires and Autolite platinum plugs tonight (in the dark, with one o' them ball caps with the LED lights built into the rim - rock!): after a spin around a few blocks, no more CEL, no more load-sensitive stumble. After a more extensive drive, we shall see if that turns out to be the case. Fingers crossed...

I bought a valve cover gasket set at the same time, expecting to find some oil in the plug valley based on this thread, but found no oil leak, and really no significant debris aside from a well preserved bee carcass. I figured I'd replace the gasket since I was in there and I had it next to me, but nothing doing. After a fair amount of pulling and grunting, I decided that it wanted to stay put. Since it's that dry and comfy, who am I to argue?

Thanks for the help everyone. I'm thinking plugs and wires was it, and if so, that means I get to keep procrastinating on the timing belt.

procrastinating on the timing belt.