I wouldn’t think the shifter movement (interlock) was computer controlled on a 98, all mechanical. But…I dunno. I’m no Honda man. What’s up with all the Honda issues lately? I need some GM questions. Stuff that’s ‘sposed to break down and that I’m more familiar with 
The shift-button component to this radiator-replacement problem makes me think there may have been a problem inadvertently introduced into the transmission fluid cooling system. The transmission fluid is probably cooled by tubes running through the radiator. Did you have any problem loosening or connecting up those tubes when you replaced the radiator?
The common advice here when there’s suspected air in the cooling system is to bleed it again, but first put the front wheels on ramps, so the front of the car is much higher than the rear.
Ok, will do this. Yes, I do not understand why the shift button locked (I manually unlocked it) Yes, there are 2 small hoses going to the trans that I had no problem removing nor reinstalling on the new one. I drove the car today for about 15 mins, came back home, but still the rpm is at 2200 or ao No overheating thought. What if I drain the radiator and redo everything? thoughts?
The only problem I can think of with an automatic transmission that might cause a warm engine to idle in neutral at 2200 rpm would be a faulty vacuum actuated modulator valve. If the diaphragm split it could create a big vacuum leak. But I doubt a 1998 transmission even uses that part.
My guess is the too-high idle rpm is due to either the idle air control gadget, or a problem with the engine computer’s determination of the coolant temperature. Since this all started with a cooling system repair, make sure that sensor has the correct resistance for the corresponding coolant temperature. For some reason the calibration chart for coolant temp sensors tends to be difficult to find, but try googling for it, you may get lucky. If not a visit to your Honda dealership should work. Once you know that info you can compare the sensor’s resistance for various coolant temperatures you measure using a thermometer in the radiator.
So, I’ve driven the car for about 500+ (even went on a 3-hr trip this weekend) and the high rpm is still there. 2000-2250 rpm when parked. After driving, I’ve left the car’s fan on for hours (restarting the car every 15-20 mins to avoid battery drain) and still the same.
Not sure if I will take it to the mechanic as it’s a very old car and if it were to die, I’ll just get another one.
Any thoughts on anything else I could do or any adverse effects to be expected from this RPM?
Thank you.
I drove the car with relatively high RPM (about 1800-2000 RPM when idling, 1300-1500 RPM when running) for about a year or so. No visible problems.
However, after about a year, the car began to do this (it may be related to all this or not):
- First, it was fine, I was able to drive it ‘normally’’
- After warming it up (by driving about 10-15 miles) and parking it, going to the store, then igniting the car, it all was ok, but after about 3-5 minutes, its RPM started going up and down, up and down, for about 5 minutes (between 500-2500 RPM, I think), then it normalized it and I was able to drive. Crazy!
What could this be?