Just sort of what the title says.

I took my 2016 Accoed EX-L 2.4/CVT in for its 4th transmission service (drain and fill) at 225K miles. They gave me a bucketlist of suggested maintenence. One being the already replaced valve cover gasket. I decided to replace that myself with a new cover purchased at Amazon (had great reviews). The next day, I noticed when letting off the gas pedal to coast, the CVT was acting like it was down shifting. I would feel a surge restriction and could see the RPM's increase. If I lightly pressed the gas peday, it would go back up in gear and RPMs would drop. I took the car back to the dealer and advised them of this odd feeling. They looked at it and only found a code in the ECU for mis-fire on cylinder 1 (which I am sure was from the plug valley being heavily doused in oil from the original valve cover plug seal being bad) They found nothing else and thought that may have been the problem.

It was not.

I have also realized my idle speed is high even after warm up. I am sitting close to 1200 RPM in park and 1000 RPM in gear. The car is definitely way off and I can't figure out what may be going on.

I just finished a second deep look into my actions to replace the valve cover assembly, with everything appearing to be plugged in and the 2 vacuum lines (left back maybe 3/16" and 5/8" on the right side of the valve cover) all connected with clamps in place.

Could there be something with the replacement valve cover to cause an issue? I did see a gasket in the center front on the underside of the valve cover itself. Could that cause an issue?

I am baffled and appreciate anyones suggestions to help me figure this out.

Thanks in advance,
Mike

 

High idle means possible vacuum leak. Take a spray bottle with water and spray around the valve cover. If the idle changes, then you found a vacuum leak.

If you have a scanner, see if the long and short term fuel trims are showing a lean condition. Zero is normal, and positive numbers mean more fuel than expected is being added based on the mad sensor.

 

Sadly I am away from the car for several days, probably a week or so now.

I will definitely use a water bottle and check for a leak. could the valve cover itself be the problem? Should I order a replacement in advance to be ready? I am concerned if something may be bad for the CVT with this issue.

Would that affect the transmission behavior ?

I did notice when in sport mode, there is no down shift recognized, maybe because it already is in a lower gear ratio.

What is the little plug that I swapped on the back left of the valve cover? It is red and is held in with a 10mm bolt. Possibly a vacuum port block and leak area?


Thanks VERY much for your inputs. I do have a mid level scan tool and will try to figure out your second suggestion if I don’t recognize an issue with vacuum.


Mike

 

I sprayed like crazy and had no change in idle speed.

looking with my sub par scan tool, I see 4.7% short term fuel trim -bank 1 and .8% on long term fuel trim - bank 1. Short term fuel trim (B1-S2) is 0 to -.8% fluctuating.

my question now is relating to the valve cover I replaced with. On the under side of the valve cover is a port with a gasket seal towards the front of the car onto a port in the head. What is that? Could there be a problem there causing this issue ?



thanks in advance,
Mike

 

I think the port is the PCV system. I don't know if that could cause your issues. I put a link to a good diy video on replacing the valve cover gasket for your era accord. Maybe you missed something with the install?

Did you mess with the cooling system, like change the coolant?

 

I did after this issue started have my water pump replaced with thermostat and housing. But my transmission was already acting weird and had a high idle. I used the Aisen brand pump and Honda coolant with an OEM thermostat and housing. I will look at the video in a few minutes, thanks for the link.

What are your thooughts of my fuel trim numbers that I observed?

I hope I can find something to figure out what is going on. Couldn't the PCV system cause an intake vacuum leak? I may order a replacement valve cover to put on.


Mike

 

The fuel trims look normal, so you may not have an external vacuum leak. The sum of those 2 numbers ideally should be zero. Anything less than 10 is pretty good.

You may also have air in your cooling system. With the engine cold, remove the radiator cap and start the engine. This will allow air to escape from the system.

 

I will do that soon as it should be cool before too long.

what are your thoughts on my transmission behavior ?

it downshifts whenever the accelerator pedal is not depressed any. In drive or in sport mode.

Thanks again
Mike

 

That doesn't make sense either. I'm looking at a 2010 accord shop manual that is close to the 16 accord engine. There is a ground on the passenger side of the valve cover that is important. Make sure you got your grounds connected properly. Maybe the video will show the ground location better in case you missed reattaching.

 

OK...

I opened the cooling system and started the car. The coolant began to raise and wasn't going down the overlow tube well. I opened it up and shut the motor off. The level went back down slightly. I cant say I saw a bubble exit from below but it was possible. I started it back up and got a turkey injector to remove coolant as it expanded with motor heat. I went through several tubes and putting it into the overflow bottle. Until it seemed to level out. I left coolant to the top to eventually place the radiator cap back on a full system. BTW... the radiator cap was replaced with the water pump work - new from Honda also.

The idle may have actually went down. I am below 1000 now most of the time, but it will surge up now and then to 1100-1200 and then drop back down to 850-900. It still seems a little higher than it used to be. I drove it around the block and parked it.

Should I remove a battery cable overnight to let the ECU reset and learn again?


I'm still wondering about the transmission behavior after the dealer did a drain and fill on it. When I say downshift, I know its a CVT. It just goes into a lower ratio. I can feel the engine restriction to slow the car down and RPM's bump up until I press on the accelerator again.


Mike