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Discussion Starter #1
I'm new at working on these electronic controlled engines, so I'm hoping for some help.

A couple of days ago, I changed the alternator on my 2005 ZX5. 172,000 miles. That's the only thing I've had to "repair" on the car. After the change, the car ran fine. We are the original owners. Anyway, my son was driving the car a couple days later. He said the car was running fine, someone hit the brakes in front of him, and he slammed on the brakes pretty hard. When he hit the gas to go again, the engine started stumbling on him.

He brought the car to me, and told me about it. I started the car (which was difficult). The engine itself isn't making any noise like something is wrong (rod knocking, etc.) but it definitely has a miss. So I just stared at it a minute, then decided to check something out.

With the motor running, I pulled the electrical connector from the #1 injector. The motor just about died, then I put the connector back on. The motor smoothed out, but with the same miss. I then did the same thing with the #1 coil pack. Same results. I did the same thing with the #2 cylinder, and got the same results.

When I disconnected the #3 injector, there was no change in the way the motor was running. When I disconnected the #3 coil pack, there was no change as well. I then disconnected both the coil pack and injector from the #4 cylinder, and still there was no change in the way the engine is running.

To me, this is telling me there is something wrong with the fuel/spark on the #3 and #4 cylinders. I thought maybe something stupid happened with the electronics, so I disconnected the battery for a 1/2 hour, reconnected it, and started the car with the same resulting miss.

There are no warning lights showing on the dash board, so I am at a loss here. I thought I would check the forum to see if anyone had any idea as to what is wrong with the car. When I changed the alternator, I did not disconnect anything except the negative cable on the battery, and the wires going to the alternator.

I did notice while I was changing the alternator, there is a small black box with 2 wires coming out of it. One wire is grounded next to the power steering reservoir, and the other wire is connected to the wiring harness on the top passenger side of the engine, on top of the valve cover. One of the wires has broken off of the box. This is the only thing I can see wrong with the wiring on the car. The car ran fine with this wire broken.

Again, if anyone can steer me in the right direction, it would be greatly appreciated.

Eric - Pittsboro, IN
 

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Check the vacuum booster line... comes off the back of the intake manifold ->-> brake master cylinder

Its a hard plastic vacuum like I've had it pop out the mani. Before... makes motor run like prue crap
 

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Pull all the plugs. Use a spark plug deposit diagnostic chart to see if the plug deposits can tell us anything.

As far as the brake booster goes, if there is a problem with it, it is worth replacing the check valve to see if that's it. Really, those should never go bad, but it is possible. The part is a generic part shared by all vehicles and is $4. That's what the brake booster vacuum line plugs into at the brake booster.
 

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Strange responses!! Isn't anyone going to try to answer the OP's actual question?
I have no experience with Duratec, which I believe the engine is for this vehicle, but -
Since both the FI and spark are triggered by cylinder specific timed ground pulses from the CPU, but have battery present steadily during engine operation, I'd suspect that a wire or connector that supplies battery to both FI and COP (coil on plug) units for cylinders 3 & 4 has broken or gone open, probably due to the violent stop. Look for something electrical that got yanked too hard during the stop.
Good luck,
Monoblanco
 

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Discussion Starter #6
Strange responses!! Isn't anyone going to try to answer the OP's actual question?
I have no experience with Duratec, which I believe the engine is for this vehicle, but -
Since both the FI and spark are triggered by cylinder specific timed ground pulses from the CPU, but have battery present steadily during engine operation, I'd suspect that a wire or connector that supplies battery to both FI and COP (coil on plug) units for cylinders 3 & 4 has broken or gone open, probably due to the violent stop. Look for something electrical that got yanked too hard during the stop.
Good luck,
Monoblanco
That sounds reasonable. It is a duratec. I hope that wiring diagram in the Haynes manual is up to snuff...

Thanks for the responses. I'll reply with what I find, and with my luck lately, probably a request for more direction, so this doesn't turn into an unsolved mystery thread.

Eric - Pittsboro, IN
 

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Hi tumunga -
Glad my guess may have been good - if B follows A, that doesn't prove cause and effect, but it certainly suggests a possible relationship and a good place to start.
I'm not optimistic about the Haynes manual - the wiring diagrams are pretty generic, but maybe you'll get lucky. I've got the factory manuals for the 2002 focus lineup and have found them extremely valuable but the 2.3 liter Duratec is not covered, since it was not part of the mix at that point.
Good luck and please let us know your outcome.
Monoblanco
 

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Discussion Starter #8
Update-

I haven't had a chance to look at the car yet. Gonna take a vacation day from work Thursday, and work the car over.

Just one more thing. I did smell something like burnt electrical when I popped the hood on the car this morning. Real faint, but no mistaking that smell. This is gonna be fun.

thanks again for the help, and I'll post again as soon as I find something.

Eric - Pittsboro
 

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Look around the EGR tube. I've seen many threads with people who had issues with the EGR tube burning wiring. Your EGR doesn't have a separate DPFE, but it still has exhaust running to it.

I think I posted that message in here thinking I was in a different thread or something. The black box on the front motor mount that grounds to the rt side strut tower is the noise suppressor. If that ground side of the box is disconnected, it should be re-grounded. If the input side of the box is disconnected, it should be shielded with tape until you can get a replacement, or reconnected if possible. If this side of the wiring is grounded, that results in a no-start issue from a blown fuse that will continue to blow until that wire is protected from grounding. It's just a radio noise suppressor- if you really want to, you can get another electronic noise suppressor to go in it's place. The part there is available at Ford Dealers.
 

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Discussion Starter #10
Ok, the electrical diagram in the Haynes manual didn't even show my 2.0 Duratec coil packs. Oh well.

As for the engine, I checked all the electrical wires, and couldn't find a thing wrong with them. I pulled the battery, and the battery tray out and checked under there as well. Nothing. So I checked all the connectors, applied dielectric (?) grease, and reconnected them. Still ran like crap.

At this point, I pulled the plugs. Other than the gap being a little large, they all looked the same, except for #3, which smelled like gasoline. I whipped out the compression gauge, and checked the cylinders. #1, #2, and #4 were all above 150 psi, but #3 hovered around 30 psi.

I recon I'm pulling a head off this weekend? Head gasket maybe?
 
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