Hi Scotty,
Love your channel! I have a really weird issue in experiencing in my car. I've been to the dealership couple times and I think they have no idea.
Vehicle: 2012 Honda accord (V6, manual)
Problem: vehicle vibrates (more so the seat than the steering) during highway speeds, only when I accelerate. So if I'm going so 100 kph (~60 mph), when I accelerate the car vibrates. As soon as I let go, it's smooth as butter.
So far the diagnosis from dealership was that front passenger side CV axle needs to be replaced. Done that (after market part, new, not Honda genuine). Vehicle still vibrates, though now vibration seems a bit less.
Should I also change the driver side CV axle? This issue has been driving me nuts. 3 mechanics and everyone tells me different things.
Also, issue was present when I had the summer tires on. And the issue is still present after putting on winter tires. Tires are balanced so don't think it's the tires.
Any kind of help would be really, really appreciate. I love the car and would really want to fix it and keep it.
Thanks in advance!
Hey bud. Scotty may chime in here later but I also have experience with hondas and vibrating engines. I need to ask a little more about your trouble here though. Is your car giving a check engine light? Does it start to flash at highway speeds? What kind of codes are being sent out if so? I ask this stuff because it seems that your problem stems from the engine shaking in response to a bad air/fuel ratio, which may be causing misfires.
A/F ratios at highway speeds are more heavily calculated in the car's ECU than at city speeds. If a car can pull 28city/38hwy or some crazy number, it can be a huge selling point. For this reason also, smaller problems like vacuum leaks can become larger problems at highway speeds since the parameters for the A/F ratio at these speeds are more stringent. You may have gotten hustle-town'd with the axle stuff, sorry to say. Usually with that you would notice some ripping in the protective rubber boot and a noticeable grinding or clunking noise on sharp turns.
Hey,
Thanks for the reply!
When I got the vehicle, it did not come with the OEM engine intake. Instead, the previous owner had installed a straight pipe.
I did run a OBD2 diagnosis on the vehicle and the engine light is on. The 2 codes I get back are p0172 and P0175. As little as I know, looking online it tells me that the code means the engine is running too rich. This is probably because of the straight pipe sucking in too much air?
When I took the vehicle to Honda dealership to see what's up (my local mechanic had given up), they said it's the CV axle. Do you think it's not the CV axle and rather the engine shaking itself?
With some intuition and technical problem solving you can find the root cause to all car problems (and life problems). Good on your mechanic to throw in the towel, a less honest one might have milked you for a bunch of repairs that it didn't need. I bought a car a few years back that also had a straight pipe aka cold air intake installed. From some research I know that these things can barely add maybe 5 horsepower and for the trouble they are to clean and replace it is better to just keep an OEM intake and filter. Have you cleaned or changed the filter since buying the car? It could be that it is bogged down with oil and dust, this would cause the ECU to send out more fuel to even out the A/F ratio.
As far as the shaking goes, you mentioned said you noticed it coming from the body more than the steering wheel. If the shaking was related to the wheels or suspension you would likely feel it more in the steering wheel than the body since the engine is connected to the front frame and subframe. It would be a good idea to keep a 2dollar notepad around your glove compartment where you keep track of all problems and repairs for your car. Your service manual will give good recommended service intervals for parts but when you are buying it used there's no guarantee that the previous owner followed them. A car your age will start to develop small leaks around the intake manifold and throttle body gaskets, depending on your driving habits. There is a troubleshooting technique called propane enrichment that is safe and reliable enough for the DIYer to do. All you need is a small camping propane tank, a release valve, and some vinyl tubing. There is also the OG smoke trick that scotty has with a cigar, that works well too.
Hello,
Just to close the loop, replacing the CV axles fixed the issue.
First replaced the passenger side CV axle, vibration reduced. Then replaced the driver side CV axle, vibration gone.
Contrary to what the dealership recommended, I did not need to use genuine Honda parts. I just used a good aftermarket brand, Track Motive.
Thanks
If you dot have any code, check the LTFT and STFT too. Clean the MAF sensor and change the fuel filter. Lots of things could cause the vibration that need to be checked out. If you engage the clutch while it vibrates, does the shake go away?
Hey,
Thanks for the reply!
Not much of a mechanic myself, i believe LTFT/STFT has to do with the fuel mixture ratios?
Running the OBD2 sensor I do get 1 codes, p0172 and P0175. Which is that the engine is running too rich.
When I got the vehicle, it did not come with the OEM engine intake. Instead, the previous owner had installed a straight pipe. It could be that it's just clogged
As for the clutch, no. As soon as I let go of the accelerator, the shaking stops:
I even tried the following scenario:
On high speeds. Car starts to vibrate on 100 kph, I continue to accelerate until 120. As I accelerate, it shakes. When I let go of the accelerator, the shaking stops.
You kinda answered your question. Change the intake air to the original. The air/fuel ratio on your car is messed up.