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HDGENE
HDGENE, Ford Senior Master/Diesel/Trans
Category: Ford
Satisfied Customers: 4909
Experience:  25 years Auto experience, Ford ,GM, Chrysler, Asian & European
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Skipping after car warms up; check engine light indicates

Customer Question

skipping after car warms up; check engine light indicates problem in 4th cylinder; injector switched from 4 to 3, problem code remains indicating problem in cylinder 4; PCM replaced (used PCM installed) and problem remains; current mechanic thinks the problem is with the "harness" but first he must replicate the problem; plans to take car in couple of days, let idle/test drive until skipping then examine harness to pinpoint the problem; reasonable? thoughts?
JA: Does the light stay on, or does it blink?
Customer: usually steady but sometimes blink (less than 10% blink)
JA: What is the model/year of your Ford?
Customer: 2003 Ford Focus Z5X
JA: Are you hoping to fix this yourself? What have you tried so far?
Customer: i won't be fixing it myself
JA: Anything else you think the mechanic should know?
Customer: my mechanic says this is not a problem with a major component so in his opinion the additional labor (3 hours) is worth the money
Submitted: 6 months ago.
Category: Ford
Customer: replied 6 months ago.
is the mechanic on the right track?
Customer: replied 6 months ago.
When I say, "Is the mechanic on the right track", I am referring to the mechanic here that is working on the car.
Expert:  HDGENE replied 6 months ago.

Hello, that is a possibility, providing the misfire stays on number 4 cylinder, the ignition system has been checked with the same results and the engine passes a compression test. But depending on the miles on this engine which should be a dual over head cam engine, they had issues with the crankshaft endplay causing intermittent misfire issues. The crankshaft position sensor reads off the flywheel, if the crank has too much endplay, when the engine gets hot it can cause the crank to float and have misfire and crank sensor codes as well. Main thing is to confirm the source of the misfire, if the coil or injector is missing a ground signal from the pcm, or if its a base engine mechanical issue

Customer: replied 6 months ago.
How does the "harness" play into this? Is the "harness" a "base engine mechanical issue" as you say?
Expert:  HDGENE replied 6 months ago.

The wiring harness would be an intermittent electrical issue, if he thinks there is an issue with the wiring, he can overlay a new circuit from the pcm to the injector. Base mechanical issue would be if there is an issue with the crankshaft enplay/major engine repair

Customer: replied 6 months ago.
I don't know whether the ignition system has been checked; I don't know whether the engine has passed a compression test. The car has 65,000 miles on it; I presume the engine is the original engine.So should I ask the mechanic to check the "crankshaft endplay?"
Expert:  HDGENE replied 6 months ago.

I would have him test the ignition system first for an intermittent misfire, unless he is getting codes with his scan tool indicating an issue with the fuel injector circuit.

Customer: replied 6 months ago.
the codes indicated a problem with the 4th cylinder; he has eliminated the injector as a problem (as described in my original question) and now is focused on the "harness"
Customer: replied 6 months ago.
i think the code was P304
Customer: replied 6 months ago.
P0304
Expert:  HDGENE replied 6 months ago.

I would be looking at a faulty ignition coil pack or bad coil wire/worn spark plug, water or oil leaking in the valve cover gasket the ignition wire to short verses an injector issue. Ignition system faults are more prominent than an injector issue

Customer: replied 6 months ago.
Injector issue has been eliminated. They are not looking at injector issue.He thinks it's the harness. Is he correct?
Customer: replied 6 months ago.
34;Faulty ignition coil pack" or "bad coil wire" - do these items relate to the "harness?"Also, the plugs were replaced.
Expert:  HDGENE replied 6 months ago.

No the ignition coil pack fires the spark plugs, you have igniton wires that rrun from the ignitin coil at the rear of the engine and the igntion wires go from the coil to the spark plugs. Id be looking at a failed igntion coil for a misfire issue first.

Customer: replied 6 months ago.
if the "ignition coil" checks out, does the harness make sense?
Expert:  HDGENE replied 6 months ago.

Yes, if everything else checks out. Then he can run a new wire harness section from the PCM to the number four cylinder issue

Expert:  HDGENE replied 6 months ago.

Do you need more help with this concern? If I was helpful, please leave a positive rating

Expert:  HDGENE replied 6 months ago.

Hello, do you need more help with this concern?

Expert:  HDGENE replied 6 months ago.

Hello, if you need more help let me know, if I was helpful, please leave a positive rating, the question remains open until it is rated.

Expert:  HDGENE replied 6 months ago.

Hello do you need more help with this concern?