2010 Acura MDX Valve Adjustment

Car Troubles: Part 1

In February 2024, my family and I were driving our 2010 Acura MDX, and a pretty awful thing happened. I mean, it could have been much worse, but it seemed pretty bad at the time. 

We were driving to a family vacation spot. Everyone was upbeat and enjoying the ride. About 1.5 hours away from our destination, and while driving on the freeway, the engine began to misfire. This caused the engine to vibrate roughly and made everyone in the car feel not-so-good about actually making it to our vacation spot. That is a major bummer when you have 4 kids in the car! Tears started flowing (not mine though).

Thankfully, I had my onboard device (OBD) scanner (Amazon link) with us in the car, and I scanned the error code. It told me we had a misfire in cylinder 4. So, now I knew where to start. I pulled off as soon as I could and pulled out cylinder 4 ignition coil and spark plug. The plug electrode was bent, which made me feel good and bad. I knew what the problem was, so I felt good; but I didn't know why it was bent, so I felt a little bad (worried).

We found a local Auto Zone about 20 minutes away, and prayed the engine would make it there without anything worse happening. That was a pretty stressful 20 minutes.

We arrived at the Auto Zone, bought a replacement plug, installed it in the parking lot, and everything was good again! We felt so much better! Wow.

We had our nice vacation (at Great Wolf Lodge, which is really fun!). We drove it all the way home at the end with no problems.

So, why am I writing this post? The story didn't end there...

Car Troubles: Part 2

A few weeks later, we were leaving to drive my oldest son to an archery tournament, and boom! It happened again. Engine shook. Cylinder 4 misfired again. Blah. We turned around and went home, and I had to drive my son to the tournament in our other vehicle.

I spoke to everyone I knew that understood cars and engines, and I got several recommendations. Here is a quick summary:

My dad: He suggested that I consider doing a valve adjustment or have the cylinders inspected for damage.

A local mechanic: Recommended I not use Bosch spark plugs (which were currently installed) and switch to NGK (OEM) plugs. They also suggested using BG Advanced Formula MOA with every oil change to clean up the cylinders. They also put a scope into cylinder 4 and took a few pictures (see below).

Another local mechanic: Agreed that spark plugs could be a major factor, but wasn't sure why only one of the cylinders was misfiring if all 6 plugs were Bosch. He did not want to do the valve adjustment for me, because he wasn't convinced it would help.

Acura technician: I started shopping for a new vehicle because I thought the Acura might be dead or dying; so I went to a local Acura dealership to test drive a vehicle (a Lexus, actually). Oddly enough, the salesperson was a former Acura technician with 25 years of experience. I told him the story I just told you, and he suggested I do the valve adjustment.

Solutions: Part 1

Since spark plugs are relatively inexpensive, I went ahead and ordered the NGK plugs and installed them. I also started using the BG Advanced Formula MOA at each oil change. The spark plugs seemed to be a major factor, because there were no misfires or further issues after replacing them. 

Thus, lesson #1 I learned is not to skimp on spark plugs. The Bosch plugs were not going work in this engine.

I also learned from my research that Acura engines are prone to valve issues, particularly the tightening of the exhaust valves; and that can cause serious problems. The MDX was around 175,000 miles when I replaced the plugs, but I was also concerned that the plugs might have been a band-aid on a larger issue.

Amazingly, we drove the MDX from Missouri down to Gulf Shores, AL during the summer of 2024 and had no issues at all! It was slightly unnerving for my wife, but I promised her we could buy a new car if the MDX messed up another vacation! 

So, the MDX did really well for several months, but I had already decided that I would do the valve job. I was just waiting for the weather to cool off so I didn't have to sweat to death in the garage while doing this.

Solutions: Part 2

While researching the valve adjustment job, I came across this YouTube video on the channel Make Acura Great Again (I love the play on words, BTW).

I never would have attempted this job without a video like this one, so I'm grateful to him for all the time spent making this video. It's very comprehensive.

I ordered all the supplies (gaskets, cleaners, etc.) and waited for the right time.

Then finally, the weather cooled off in Missouri, and I had a Monday off for Columbus Day! 

Perfect. (As you'll see, nothing ever goes perfectly! Haha.)

Here are a few pictures from the job in progress. It wasn't too terrible, except for getting the rear valve cover in under the wire harness was pretty irritating! 

And yes, I dropped a few sockets along the way. Magnetic pick up tools are worth their weight in gold!

The biggest problem I encountered was with the front valve cover. While removing the ignition coil seals from the cover (to replace them, of course), the cover actually cracked and broke. After looking at the cover more closely, I realized there were several places where the metal was beginning to crack; so, that convinced me that this "problem" was actually a blessing. That cover needed to be replaced!

I ordered this Chinese valve cover to finish the job and had to wait for Amazon to deliver. I know OEM parts are better, but seriously, this car has 181,000 miles now; so, I'm not spending $600 for an Acura part.

The job is done now, and I only ran into one more issue...

I forgot to plug in the ignition coil on cylinder 3, causing (obviously) a misfire in that cylinder when I re-started the car. I had to use the OBD scanner to find out the problem, and it pointed me right to it. I felt like an idiot for missing that; but such is life as a DIY mechanic.

Lesson #2: Double/triple check the connections to your ignition coils before restarting your engine after a job that required their disconnection.

After plugging the coil in and restarting the car a few times, the codes are cleared, and all is well. 

As a side note, Acura computers are pretty weird; when a misfire happens, it throws a bunch of other codes related to emissions systems, trailer assist, traction control, etc. Those are completely unrelated to the real problem, so don't freak out if this happens to you. It could just be a loose connection to your ignition coil or a bad spark plug.

For the sake of completion, here's a short video of the engine running properly after the job. It may not make you feel happy, but I'm pretty happy to hear it running smoothly again! 

Outro

If you are a DIY at-home mechanic or just like to chat about car stuff, let's connect online (see 'Connect' section on left sidebar).

I enjoy working with my hands and wrestling with challenges. I also enjoy saving some cash by doing these jobs at home! 

And what do I do with that money? I'm glad you asked. Since I saved about $700 by doing this job at home, I moved that money into the stock market; and someday that $700 savings will be a lot more than $700 for me and my family.