Rep Power: 0

[size=17px]2000 Civic DX automatic d16y7, 230k miles, no check engine light or codes, alternator and battery tested fine yesterday.[/size]

[size=17px]I just changed my head gasket, spark plugs and wires, 2 of the 3 accessory belts including the alternator belt, fuel injectors, thermostat, and all the gaskets and seals associated with those repairs. Now the D light flickers and the RPMs dip and rise even when gas pedal and terrain remain constant (it dips far more often than it rises). Also the AC doesn't seem to be cold anymore but I don't know if it's related. Other dash lights are fine, no dimming or flickering elsewhere.[/size]

[size=17px]I tried tightening the alternator belt. There was some improvement, but gets worse the farther I drive (I thought I'd fixed it last night during my test drive with no lights or AC, but it came back slightly when I turned on lights and AC, and it got pretty bad near the end of my 40 min commute today). I think I have it as tight as it will go now, but there is still some play in the belt (I can twist it 90 degrees on the upper portion). I thought it might be the wrong belt but I've seen the same belt used in other repair videos (says 4pk0800 on the belt).[/size]

[size=17px]I've heard the D light blinks to warn of transmission issues, but videos I've seen about it show blinking at a consistent rate. Mine is flickering erratically and sometimes looks fine for a while. I do see a bit of correlation with shifting up and hard acceleration, but not all the time. I even got on the freeway this morning without it happening. [/size]

[size=17px]The only peculiar shifting I notice is occasionally when I brake to slow down, the RPMs will jump up higher and then float back down. So far it's only happened once in the 40 miles I've driven since the head gasket job. It has done that before that, but maybe only 3 times in the last year. [/size]

[size=17px]Head gasket job took about 4 weeks because I broke a fuel rail stud and a fuel injector and parts took a while, so the battery was disconnected for a while. Battery is about 2 months old.[/size]

[size=17px]I'm running out of ideas. It really feels like inconsistent power, but I would not be surprised if it was transmission or throttle body or fuel related. Injectors are new but the fuel filter has likely not been changed in the 50k miles I've owned the car. I'm very new to car repairs and there are still some systems I'm not familiar with. I've had it for 9 years and am only just now learning how to take care of it on my own.

Thanks for reading.[/size]

 
Rep Power: 222

What voltage is the alternator putting out? And might need to go a little tighter on the belt

 
Rep Power: 0

I'll need to get a voltmeter and check myself, I didn't ask when they tested it at Advance. They said it looked good and normal though.

The alternator is as far as possible in the tensioner bracket. I can't make it any tighter.

 
Rep Power: 0

So on my drive home, I thought I wasn't going to make it home.

In 4th gear (my highest gear) the RPMs were going crazy and it felt like the car could die any second. I drove the rest of the way in 3rd and it was a very normal drive home.

I don't have a tachometer, but I can hear what's going on pretty well because my exhaust fell off.

I'm going to read up on transmissions.

 
Rep Power: 222

Might need a new belt, stick or auto?

 
Rep Power: 367

from his profile, AT, so trans is slipping

 
Rep Power: 0

I'm confused about what slipping means. Is it where the rpms shoot up but your speed stays constant? In my case, my speed is dropping with the rpms as well.

 
Rep Power: 0

It is a new belt.

 
Rep Power: 222

A new belt that's the correct length.