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A recent discussion on the Reddit r/MechanicAdvice forum presents an excellent opportunity for car owners new to DIY repairs, offering a valuable lesson on what not to do and what to do to increase the likelihood of a successful car repair.
From the OP in a discussion titled "Did My Own Tune-Up, Then This Happened — Any Advice? 2006 Ford Fusion V6 With a Little Over 164K Miles" we learn that a novice with limited experience and tools has run into trouble with his DIY repair.
"I'm an amateur. Generally, when it's an issue with my car, I look up a YouTube video on how to fix it. As the title states, I decided to do my own tune up instead of having to go to the shop. Took everything out replaced spark plugs and ignition coils put everything back and tried to start it. Engine turned on then stalled after a minute or two. Uncle told me I forgot to gap them spark plugs, so I took everything out again, gapped each plug, put everything back in and now the car sounds like this. Any ideas on what the issue is?"
From the post, the OP includes a brief video of what his car sounds like after his repair attempts.
The sounds indicate the possibilities of multiple causes that include:
- Misfiring engine with some cylinders not firing.
- Improper gapping on spark plugs.
- Spark plug boot(s) not connected to coil(s) correctly.
- Cracked porcelain on spark plugs or cracked wire causing arcing.
- Wiring harness in which the wrong connector is connected to the wrong cylinder (I know this is very unlikely, but with a novice DIY mechanic, anything is possible).
- Bad replacement coils.
- Vacuum leak from manifold or other source(s).
Post Comments Were Mostly Helpful
Many of the post comments were repeats of the above possible causes. A comment from YOdotHeThiNg (Top 1% Commenter) is a good place to start on diagnosing what is going on:
Sounds like a huge vacuum leak, can't tell if that's a hiss or a hum in the video. Check all your vacuum hoses, make sure anything that was bolted or screwed onto. The manifold is still there and make sure the intake manifold gasket didn't fall out when you flipped the manifold in.
Even more helpful advice was to put an inexpensive scan tool on the car and narrow down what cylinders are affected:
"This started after you tuned it up? If so, check the connections to the coils... sometimes they can feel like they are locked in, but they aren't. Check to make sure all are pushed down tight onto the plug as well. Check all vac lines to make sure you didn't accidentally knock one off during service. Otherwise that should throw codes pretty quickly...get a scanner and find out what cylinder is missing. You can get a cheap one to just read a code for like 30$." ―whatthehellisgoingon
But let's not forget that what the OP is going through is what all DIY mechanics have to go through―learning from our mistakes.
Hey OP, this is how we learn. Regroup and get this fixed. And do not let minor setbacks stop you from working on your car in the future.―TenderfootGungi
What the OP Did Wrong
- Throwing old parts away before the repair is done.
- Relying on a single YouTube video to instruct himself on the tune-up.
- Not supplementing the YouTube video with car repair manuals and other resources.
- Not fully understanding the repair and how things work on his car.
- Not owning necessary tools such as a good torque wrench.
- Not taking photos before and during the repair.
- Reusing old gaskets.
Related article: Car Tune-Up Truths Car Owners Need to Understand Today
What the OP Did Right
Credit, however, is given to the OP for possessing the verve to DIY his car repairs. And the best thing he did was step back from the repair when things were not turning out as he had hoped and sought help online through a forum.
Related article: Save Thousands Yearly in Scam Car Repairs and Maintenance With This Guide
In many cases, DIY owners get caught in a spiral of firing the parts cannon at a problem until something works and/or gives up.
The OP's best course of action is to find some resource materials like a Haynes repair manual on this model; peruse multiple online explanations of how COP (coil on plug) ignition systems work and how to trouble shoot one, as well as online explanations related to vacuum leaks; buy an inexpensive scan tool to narrow down where the problem lies; and buy a torque wrench to use along with the torques specs he should find in the Haynes manual.
Post Comments Not So Helpful?
In multiple comments, there was some confusing advice about ensuring the coils were placed in the correct order in the engine to avoid altering the firing order of the cylinders.
This is confusing because a coil-on-plug (COP) ignition system is where each cylinder has an ignition coil mounted directly on top of the spark plug. This configuration eliminates the need for a distributor and the spark plug wires of older, traditional ignition systems in cars and trucks.
The coils individually send current to its attached spark plug under the control of the ECU (electronic control module) in a precise order based on input from sensors linked to the crankshaft and camshaft position.
In other words, the coils should be identical, meaning that it does not matter which one goes to which cylinder as long as the wiring harness from the ECU is correctly oriented with the correct cylinder.
In the traditional ignition system, there was a single coil with a distributor connected to multiple spark plug wires. In this case, you can easily place the wrong spark plug wire from the distributor to a spark plug in a cylinder, causing misfiring and rough running because two or more cylinders are firing in the wrong order and at the incorrect stroke of a piston in the cylinders.
Wiring harnesses for COP ignition are typically designed to physically prevent someone from accidentally connecting the wrong connector to the coil/spark plug unit.
This then begs the question: Did some early models adopt the COP system using a specific coil type with each cylinder? Or are some post comments confusing the COP system with single coil/distributor/spark plug systems of the past?
One Best Guess of What is Going On
If I were to offer another possibility, since the car is old and plastic components such as electrical connectors are easily broken, the OP might have accidentally damaged a coil/spark plug connector on the wiring harness.
Doing so could explain why his car appears to be misfiring or not firing all of the cylinders as they should.
For more about this, here is an informative video that explains the how and why of this possibility that could be useful to the OP:
How Coil-On Plug Ignition Systems Work And The Pain Of Fixing It!
Now It Is Your Turn to Help: Do you have any advice or recommendations for the OP? Are you aware of any car model(s) that may have used a specific coil type with each cylinder, which might explain some of the confusing comments regarding advising the OP to ensure he did not place the coils in the wrong order and thereby alter the firing order?
If so, please let us know in the comments section below.
For additional articles focused on DIY car repair, here are three for your consideration:
- Exhaust Smoke Diagnosis Explained in Detail
- 3 Simple Tests to Diagnose This Common Used Car Problem
- Do This with Your Car's AC System Before Going to a Mechanic
Timothy Boyer is an automotive reporter based in Cincinnati who currently researches and works on restoring older vehicles with engine modifications for improved performance. He also reports on modern cars (including EVs) with a focus on DIY mechanics, buying and using tools, and other related topical automotive repair news. Follow Tim on Twitter at @TimBoyerWrites as well as on Facebook and his automotive blog "Zen and the Art of DIY Car Repair" for useful daily news and topics related to new and used cars and trucks.
Image Source: Deposit Photos
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