Misfire and Stumble under load '01 Focus

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Originally Posted By: 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?

If a vacuum leak is large enough, air bypasses the MAF, then creates all kinds of different problems. Normally you would get a MAF code or a lean mixture code, but vacuum leaks can cause a variety of problems.
1. Has the PCV valve been replaced?
2. Is that PCV valve an OEM part?

When a PCV valve becomes old, the spring inside it can develop metal fatigue, and let extra vacuum into the engine when it isn't supposed to. Afermarket PCV valves either have springs that fail too quickly, or they never were calibrated to function exactly like the OEM PCV valve.

It doesn't help that some Fords have really awful vacuum hoses.
 
I haven't looked at the PCV valve yet but it needs looked into also because I have a persistent oil burn smell that isn't the valve cover gasket. I also know these engines have a common problem with a PCV hose on the back of the engine that gets warm and collapses under vacuum. I noticed that the previous owner had replaced it with the improved hose, with heat shielding on it. I'd wager that it the PCV valve was replaced, it was a non-OEM. I'll pull it out soon and check it. Does the unlit propane torch method work for finding vacuum leaks? I'm a few hundred miles from an oil change so I will check this stuff then.

Being that I had limited time to mess with it today, I just tried electrical contact cleaner and, not surprisingly it seems to have worked... At least for now.
 
coil or wire is most likely. here's what happening:

it is harder to push a spark through a dense fuel/air mix than through a vacuum. When you give it more air, the voltage stacks up higher in the high-volt side of things before the spark can be persuaded to jump the gap. So if there are other weaknesses ("leaks"), the electrons will find their way out that way - cracks in insulation, etc.. Under no/low load, the plug may still provide the "easiest" path, and therefore fire properly.

This shows up most under low rpm, rather than high. If you're at WOT at low RPM, each cylinder is able to gulp in more air, and therefore build greater pressure/density during compression, which the spark must then push through.

-m
 
Originally Posted By: 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.


There is a ridiculous markup on pigtails.

Let's take Ford's WPT-1241. This is a MAF connector. It fits the new slot-style MAF used in many 2004+ Ford vehicles. It has 6 wires.

Price on Rockauto is $31.79

The actual vendor of this connector is TE Connectivity (nee AMP).

Their part # for the shell is 1-1419168-2

Their part # for the terminals is 1393366-1

I ordered 12 terminals and two shells from Mouser Electronics (enough to make two pigtails).

The total came to $13.83 ; $6.99 of that was for shipping.

The terminals cost 18 cents a piece and the shells cost $2.34 a piece.

Granted, this isn't quite a fair comparison. I still need 12 feet of 18 AWG GXL wire and about 10 minutes of south of the border labor to have two completed pigtails.

So let's add $1.20 for the wire and $2 for the labor (though he's probably NOT making $12/hour; avoiding those kinds of labor costs is why we make stuff south of the border, after all!)

Grand total for my two pigtails, wire and labor added in:

$17.03

Cost for two of Ford's pigtails:

$63.58

Still not a fair comparison. I doubt that whomever is making these pigtails for Ford is paying half of their materials costs for shipping. They're likely getting a quantity discount, too. I should also point out that Ford does include about $1 worth of splice crimps and heat-shrink tubing with their connector.
 
I had thoughts of finding some spade terminals or something like it to attach directly to the coil terminals if this keeps happening as an in-between fix before I can replace the pigtail and coil. It seems counter-productive to me to replace the pigtail and not the coil.

How did you find the part numbers on the terminals and shell like that? It looks cheaper to build my own if it follows suit.

Been almost another 2-days with no recurrence. My second dose of terminal cleaner did swell up the rubber seal on the plug so bad that it took some serious effort to get the plug to stay plugged in.
 
I went to Mouser's website and looked it up. If I remember correctly I found it by searching all automotive connectors with 6 positions, then matched it up by picture. Later on I found that the connector has the TE Connectivity part number on it so I could have found it that way too.

You won't find the ignition coil connector there. It is made by EPC. The first problem is that EPC has terrible distribution, the second problem is that it doesn't appear in their catalog. So you won't find EPC's part number for it and even if you do, you probably won't be able to find a source for it. Also EPC doesn't make the terminals, they are made by Molex or Yazaki depending on the connector. Forget about trying to get anything made by Yazaki, they have terrible distribution too.

The good news is that this ignition coil connector is the same one that Ford has used for many years on many different cars. A physically compatible connector with a different design has been used as far back as 1991 (on the 1.9L Ford Escort). If you go to Ebay and search for

Ford EDIS connector

or

Ford coilpack connector

You'll find them for about $15.
 
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Also you could look for Standard Motor Products S674. This is for a Ford throttle position sensor, but the only difference between this and the ignition coil connector is the keying...and a bit of cutting will take care of that. It's also much cheaper, around $10. (Amazing how moving the notch from the right side of the connector to the left side adds $40 to the price...)

It is the older design connector with plastic latches, not the metal latch like your Focus has. However, it will still work if you either cut the key off the ignition coil or put a notch in the connector to allow the key to fit.
 
Check your EGR system, the DPFE sensor fails often. At full throttle it is disabled so you would not notice it failing.

http://www.focushacks.com/mod/DPFE_Sensor_and_EGR_Information

I recently repossessed my 2001 focus zx3 from the brother in law and found the EGR Valve wasnt even bolted tight. The car would 0-60 in about 15 seconds and drove like it smoked 5 packs of cigerettes. Tightened it up and drove in much better this morning.
 
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Just saw this thread, haven't been on here in a while. I had the exact same problem on my pristine 80K mile 2003 ZX-2 that I sold recently, same engine. I replaced plugs, wires, and coil with all new Motorcraft parts and still had the intermittent miss under load. I can tell you that you really have to make sure and snap the plug wires onto the plug hard to make sure they connect well. Lo and behold my dealer (I work there) finally figured out the new in box Motorcraft coil was bad! To make matters worse it's now obsolete so an aftermarket one fixed the problem for good! You have to check and double check everything for these crazy little problems haha.
 
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The thing is now that I'm thinking this connector is so worn/broken that it's almost constant at any kind of load. The other day it sounded like a Subaru going up hills.
 
645-302-2.jpg


pt365_terminal.jpg
 
Try this in a dark garage:

With a hot motor, hood open, engine on, spray down the ignition wires, dist., coil packs, etc with a fine mist of water and look closely for blue sparks. Give your eyes time to adjust. This is high-voltage leaking anywhere you see blue.

Helped me track down a mis-fire. Neat trick!
 
Ok, I've still been dragging my feet with this, have been getting by with cleaning and re-connecting the plug and it was ok all week until today on the way home. I was going around a stopped garbage truck up a hill with the A/C on and it started misfiring constantly. The misfire counter on my Bluetooth OBDII scanner was in the tens of thousands. Sulfur-ish exhast smell and everything.

I'm going to order the plug from Amazon because the nearest place it's available is Summit racing and it's still too expensive there. I'm thinking, by the looks of the coil power plug that I can get by temporarily with some small female spade terminals, sections of wire and a few of those snap-on wire tap things to tie into the wire further up away from the plug.

988Z12029A-ANG.jpg


Does this sound completely crazy? I feel like this could work if I were to get the insulated spade terminals. The car is un-drivable, basically, because I've let this simple fix go on and on. I've just wanted to be absolutely sure before I'm 'throwing parts at it'. I don't think my cleaning routine will work anymore, I think the heavy load broke/burned one of the three wires feeding the coil.
 
It sounds like you've nailed it down to an electrical problem. But for future reference, what you describe could also be caused by a fuel problem. If your fuel pressure is low it could cause stumbling under load. This could be a bad or leaking fuel pressure regulator, a failing fuel pump, or a clogged fuel filter. You'd have to check it by hooking up a fuel pressure gauge. The fuel pressure should increase when you disconnect the vacuum line going to the regulator.

Also for future reference, I have had good results finding vacuum leaks by spraying with WD40. It will cause an RPM change when it hits the leak.
 
Does anyone know the gauge of the coil power wires? I have a couple different options for repairing this but I'm curious if it's 18ga 16ga or what.
 
Well I managed to splice in new wires with terminals and it's still doing the same thing seems to be misfiring on one cylinder only, number 4 according to the fault code earlier . This would not indicate a problem with the coil power wire as there are three wires and it would drop two cylinders if one wire wasn't conducting. I'm not sure where to go now.

Could one plug be so fouled that it won't fire at all?
 
Ok it's definitely cylinder 4 as I can pull that plug wire off from either end and there is no arcing whatsoever.

Zetec experts will have to advise but I think from looking at the coil that the number 1 and 4 plugs fire at the same time in this wasted spark setup. If I pull 1 off its arcing like crazy. Does this possibly point to a bad coil?
 
I feel like I'm dangerously close to going "FULL GHT" replying to my own threads over and over but I've done some more reading. I still have yet to test the coil but it looks like if I test for continuity across the plug wire terminals for cylinders 1 and 4 I may find that there is none. I did read something that says faulty ignition coils can cause damage to plugs/wires. I hope this isn't the case as I just recently replaced the plugs and wires on this car.

Right now Rockauto is looking to be the best bet to replace both coil and plug using the S674 plug which is compatible. It doesn't show a rubber seal but I could pull that from my old plug or maybe just use some dielectric grease? Anyway it's about $48 for both at Rockauto with next-day shipping. That is, if it's indeed the coil that's bad now.
 
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