Low RPM on idle

[civic98mi]

OK, my car is a d16y5 98 Civic HX. I have an intake and catback exhaust. After I start my car (cold start) it idles at normal 1500ish rpm and drops down to 700ish. BUT, once my engine has reached normal running temperature, and i'm stopped at a light or something, the rpms drop to 300ish. The car feels perfectly fine, and doesn't feel like it's going to stall or anything. What bothers me is that I have a HUGE exhaust tip (Airmass Thundermuff Catback - 5" tip), and the tip bangs against my rear xenon bumper (annoying). I just changed my spark plugs to Bosch Platinum +4, and plan on changing my wires to Nology Hotwires. (plugs didnt fix problem). I've searched multiple honda forum sites and some suggested turning the idle adjuster by the throttle body. I plan on trying this when i get home, but i've read some threads from other cars that said it didnt help. Any info of what could be doing this would be helpful.

It kinda sucks having a nice looking car that runs perfect and having people look at you weird at a light because your exhaust is beating the shit out of your rear kit.

(sorry for the run-on sentances)

[whtcivic93]

mine idles low.. i dont know why but it does

[civic98mi]

Ok, now i'm confused. I installed the platinum +4 plugs yesterday and it didnt fix my problem. Today, on the way home from work, I watched and listened carefully. My RPM didn't drop below 600ish! I let it run until my fan came on even after I got home from driving and it still idled at 600. I have no idea how it got fixed. Has to be the plugs. But why didn't it fix the idle yesterday? Did my ecu finally adapt to the "hotter" plugs today??? Whatever I guess, i'll leave it the hell alone until it happens again.

[civic98mi]

OK, it was a fluke, the spark plugs didn't fix it, as later today my rpms dropped very low again. But I just figured it out. I unplugged the IAC sensor (idle adjustment control), started the car (which gives a check engine light), my rpm was 1000, so i adjusted the IAC knob 2 turns to set the rpms at 1150ish. Turned the car off, plugged the IAC sensor back in, pulled the back up fuse for 10 seconds to clear the ecu. I started the car back up and volia, rpms are idled at 500ish. If anyone else has the problem I did, try this. Worked for me

[macmikey]

And I thought it was called Idle Air Control...That's what my dealer called it, along with a 370. plus price to replace it (I declined).

Engine runs great, lots of power, low miles (got it from a friend after it was wrecked). Idle stays high during cold start and warmup, but then goes to stall and runs up and goes down and runs up. If I listen to injectors wiith screwdriver, they actually go dead when rpm's drop off. As soon as it starts to go up again, the injectors come alive. If I hold the gas just a hair off idle stop, engine runs very smooth.

If your procedure above works, i would love to try it, but do not know where it is.

Thanks,
Mikey

BTW... I'm a Ford Truck guy (F250 SuperDuty) and this is my 17 year olds new ride. That is why I am clueless with the Civic.

97 Civic DX 2 door 1.6 with man trans

[civic98mi]

Originally Posted by macmikey

And I thought it was called Idle Air Control...That's what my dealer called it, along with a 370. plus price to replace it (I declined).

Engine runs great, lots of power, low miles (got it from a friend after it was wrecked). Idle stays high during cold start and warmup, but then goes to stall and runs up and goes down and runs up. If I listen to injectors wiith screwdriver, they actually go dead when rpm's drop off. As soon as it starts to go up again, the injectors come alive. If I hold the gas just a hair off idle stop, engine runs very smooth.

If your procedure above works, i would love to try it, but do not know where it is.

Thanks,
Mikey

BTW... I'm a Ford Truck guy (F250 SuperDuty) and this is my 17 year olds new ride. That is why I am clueless with the Civic.

97 Civic DX 2 door 1.6 with man trans

Well since you have a Civic DX, you have a throttle body that has the intake point upwards and has the intake tube curve back down, whereas mines comes straight out from the side. Nevertheless, the adjustment screw should be in the same place, which is right by the MAP sensor, on the throttle body. Some civics have a little cover you have to pop off, but im sure its there. It's a small screw that you use a flathead screwdriver to turn. When you adjust it, also remember to reset your computer ( by pulling the ECU fuse for about 2 minutes and putting it back in) (in the engine bay fuse box by the battery) Hope this helps.

[Robert0311]

Did you check the timing? My swap was idling low just right after i got it put in; and all i did was check the timing and saw that it was off so i advanced the timing just a little bit.