^^Great advice! Also be sure in addition to the filter housing being secure in the correct position, verify that any sensors and all tubing connected to the housing or intake hose are attached securely. Sometimes these items are mistakenly removed during the filter replacement process. If everything appears to be in order starting with the housing and along the intake hose to the manifold, then I would rule out that system as the cause of the issue.
Moving forward, keep in mind that just ike the motor oil, the coolant in your car also breaks down over time and needs to be flushed and replaced. I would imagine that the rise and fall in temperature is occurring because the radiator fans are cycling on as the temp rises above the "normal" and then off once the temp has returned to normal again. This is a good sign and shows that the cooling fan system is operating as it should. Since your car is not overheating to a dangerous level, even though you are driving in what would be considered adverse conditions, I would not assume the radiator, water pump, or thermostat have failed in your case either.
At this point I would consider the fact that the deterioration of the actual fluid can definitely cause slightly higher running temps, especially when in stop and go or stand still driving conditions. Since the airflow to the systems is working at its peak efficiency with your new air filter, the rise and fall could be attributed the coolant not performing as well as if it were new. Check in your owners manual or use an online Honda approved resource to determine when a radiator service is recommended for you vehicle. Although we have come a very long way in the development of the chemical additives used in the coolant and in creating a superior base product, the extreme temperatures we subject the fluid to on a daily basis, breaks down and decreases the efficiency and ability to maintain and prevent extreme temperatures over time. The recommendations from Honda are according to your mileage and have been based on lots and lots of simulated and real world testing so trust that they are accurate and do not ignore them.
If you don't mind, it would be helpful if you answered the following questions:
Is your engine oil level at the full mark on the dipstick, and does the oil in your vehicle meet any synthetic-blend or full synthetic requirements that Honda has established?
How long has it been since your last coolant flush?
Is your coolant reservoir full and maintaining the same full status over a period of a few days?
If you are able, can you squeeze the hose attached to the upper part of the radiator (soon after turning the vehicle off) and note if the pressure is high (making it difficult to collapse under the normal pressure of your hand), and verify visually that the fluid level in the reservoir is displaced as a result of the squeezing as well?
Is there any debris (solids or liquids that are discolored) visible in the reservoir or the actual radiator?
Have you noticed any leaks, even very small drops of coolant? (place a large piece of cardboard under the engine bay and check after the car has sat overnight)
With your heat turned on the hottest setting and the highest fan speed, is the output from the vents at the expected high temperature?... Also under these settings does the temperature gauge on the dash remain constant or lower, even slightly?
What was the outside temperature when the problem occurred?
How long had the vehicle been running and how long had it been at an idle or very low rpm/speed?
How many miles are on your vehicle?
...sorry for being so lengthly, but in order to provide the best opinion without seeing the car, it's important to be very thorough and to provide very detailed information about the events, circumstances during the issue, and have information about the normal use as well as age of the car.
If you don't have the time or simply do not want to preform these steps, stop by a quick service center such as Valvoline or other 15 minute place and explain to a manager what is happening. They will almost always take the time to diagnose the problem for absolutely free, and be very candid about if they can fix the issue or not. It seems to me that unlike a dealership or corporate owned full service mechanic shop they always start with the cheapest, easiest option instead of working down from the top of the price/cost list. I always stop in when I have any problems and they are always very honest about if they can help, and the managers will usually take the time to explain the procedures they use to diagnose and resolve the problem. Most of the things I know about automobiles I have actually learned from the manager at the store in my town in real time while he was working in my car. Haha, sorry that turned into a testimonial. Not trying to plug the brand just thought it's cool that they teach you while fixing for you at the same time.
Anyway get me some answers to those questions or let me know what you figured out on your own.
And if you go to a Valvoline or somewhere tell them i need to be put on the damn payroll...
FIRST , make sure the air cleaner housing was installed properly , next check coolant level in reservoir , then verify that radiator fans come on by the time the gauge hits the halfway mark.
