Misfire and Stumble under load '01 Focus

[Ifixyawata]

I've found a few old threads on other forums searching around the web and they all seem to point to the same thing.

First, some background though. I've owned the Focus in my sig since July of last year. It's been relatively problem free for that amount of time. A couple weeks ago I finally cleaned the MAF sensor (former K&N install) and netted a whopping .7 MPG on the first tank through. Besides this and a valve cover gasket, plugs and wires I haven't touched the engine.

Starting Tuesday, I noticed that starting out in 1st gear, anything more than about 25% throttle will result in bucking. The engine free-revs fine, if you downshift to pass someone, it generally revs out pretty ok. It's just that any any attempt to put any load on or even lug the engine and it bucks and stumbles like crazy. Searching around the web I've found a lot of threads that point to the coil pack and/or wire plug going into it. Something about it being a symptom that only shows itself under load, which this is.

I've only gotten as far as a visual inspection and it seems like the wires coming into the plug are under quite a bit of strain, like they're pulled tight. I'm scared at this point to try to pull the plug out for fear of totally destroying it.

I also did some diagnosis with my OBDII Bluetooth adapter and the Torque app. I ruled out the TPS by slowly working the gas pedal and noting that the throttle % increased evenly on the app. Finally got a DTC for misfire on the way home from work today. I also ran a misfire counter and logged 89 misfires on the 15 mile drive home from work this morning.

Are there any tests or any more diagnoses I can do before I decide the the coil and/or wiring to it is bad?

ps - I'm pretty disturbed to see that the pigtail for the coil is $30+ whereas a Motorcraft coil is only $25!

 

[zzyzzx]

Exactly what plugs and wires did you install in it?
Did you check for vacuum leaks? I'm wondering if this is one of those with the impossible to inspect PCV hose that breaks.

 

[Ifixyawata]

Autolite wires and autolite platinums (I believe they are OEM spec) gapped per the manufacturer.

 

[SwampSurvivor]

Does the Zetec use coil on plug? If so - that's where I would go if the plug change doesn't help. Ford had a lot of issues with COP then.

 

[Michael_P]

Coils would be my first hunch as well. Back in the day, I replaced scads of Zetec coils.

 

[Kawiguy454]

I had COP ford 5.4 motor do a very similar symptom after I lightly sprayed the motor at the car wash. the first and last time I'll ever do that.

After replacing all the plugs and a questionable coil pack my brother told me to put a lot of silicone dielectric grease on the boots ...problem gone.

 

[Bgallagher]

Originally Posted By: Kawiguy454
I had COP ford 5.4 motor do a very similar symptom after I lightly sprayed the motor at the car wash. the first and last time I'll ever do that.

After replacing all the plugs and a questionable coil pack my brother told me to put a lot of silicone dielectric grease on the boots ...problem gone.


+1 this was my thought and solution for this. I do it anyways whenever I install anything electrical/ignition related. Cheap insurance.

 

[mehullica]

What did you clean the MAF with?

 

[pbm]

I have a Zetec that I let sit for a while (almost a year) and it was running as you describe when I started it (even though it had new plugs and wires). It turned out that there was some corrosion on the coil. After I cleaned it off she has been running great since.

PS: The corrosion was on the connector where the thin wires plug into the coil...the corrosion was bluish in color.....when I scraped it off and sprayed it with WD-40...problem solved....

 

[Ifixyawata]

The Zetec uses a 4-post coil pack. It has a three pin connector, one ground and one pin each for 1/3 and 2/4 'wasted' spark setup.

I used a liberal amount of dielectric grease grease when I changed the plug wires.

I used CRC MAF cleaner.

Maybe some Deoxit contact cleaner on the pigtail going into the coil?

 

[wander2039]

Mine did the same and it was the coil. Check for cracks. Good luck on finding a decent replacement. Motorcraft part only for it.

 

[artificialist]

Originally Posted By: Eric Smith
Mine did the same and it was the coil. Check for cracks. Good luck on finding a decent replacement. Motorcraft part only for it.
I checked Summit Racing and they have variety of brands and prices.

 

[Ifixyawata]

I've seen the Motorcraft part on Rockauto and Amazon for under $30. It's crazy to me that the pigtail costs as much or more.

I figured out how to unclip the pigtail and cleaned it up real good with some DeOxIt contact cleaner. No telling if it needed it or it helped or not until I drive it to work tonight.

I did look around the top of the coil for any cracks but did not find any. Do they typically crack in a specific area? I also made sure all my plug wires were connected well.

 

[Ifixyawata]

Well, it looks like I got lucky, the car drives perfectly again. I was surprised considering the connection to the coil looked clean when I took it apart. Apparently it was dirty enough to make a difference, though.

 

[pbm]

Originally Posted By: Ifixyawata
The Zetec uses a 4-post coil pack. It has a three pin connector, one ground and one pin each for 1/3 and 2/4 'wasted' spark setup.

I used a liberal amount of dielectric grease grease when I changed the plug wires.

I used CRC MAF cleaner.

Maybe some Deoxit contact cleaner on the pigtail going into the coil?



The 'pigtail going into the coil' is where the corrosion occurred on my Zetec....once I cleaned it up the problem was solved....

 

[bdcardinal]

It is pretty common for a pigtail connector to cost more than the part is connects to. There are a lot less pigtails sold than coils, economics of scale.

 

[Ifixyawata]

I guess I started celebrating too early.

The car sat all weekend. This evening I took it for an approximately 50 mile drive and all was well. It sat for about an hour and a half and when I was on my way to work tonight it started doing the same thing again. It's not ad bad, I have to go 1/2 throttle or more now to get it to do it, but it's there. Being that it was remedied by cleaning and, in turn, moving the plug itself around I'm leaning now toward a bad plug.

It seems pretty cut and dry but any ideas where else I should look for the problem?

 

[Ifixyawata]

Before I left work this morning I plugged and unplugged the pigtail a few times with no change or improvement.

 

[ET16]

Could you have a vacuum leak?

 

[Ifixyawata]

Originally Posted By: ET16
Could you have a vacuum leak?

I probably could but I think it would present itself at idle or as an idle problem rather than just an under load problem. Would a vacuum leak be able to create a situation that would throw a misfire code like I had last time?