I have a 99 civic ex with a d16y8. For a little while now anytime im at idle or a stop my rpms will dip occasionally, some days worse than others. I changed the iacv and have no vacuum leaks. Any ideas? Mabe a fuel issue? Injector going bad?

 

Dips... as in drops and then comes right back up to the correct idle ?

 

Yes exactly

 

Yes exactly

 

If the engine hasn't always done this at idle, you likely have a fuel related change. Too little could be caused by lower voltage from the alternator, a clogged fuel filter, weak fuel pump, or even a clogged fuel sock. Too much could be caused by a cracked or leaking exhaust manifold/header or failing O2 sensor. If your fuel economy is really good, you are probably experiencing something caused by the former... if it is unusually poor, it is the latter.

 

I have a 96 d16y8, and had similar issues. These issues were fixed after the following repairs, cheapest to most expensive. Distributor cap ( my old one was cracked near a screw). I used a VMS dizzy cap, and rotor costing about $45. You may consider adding a new coil, while you're at it. Grounding wires- three total- battery, transmission, and engine - prices vary from different sources. Due to these prolonged problems, they caused leak in the cylinder head (needs to be machined - my shop charged me $1400). You can check for a leak by putting a no-spill funnel on the radiator and putting a little coolant in it. If you see a repeating blip of air coming out when the engine is running, it's a head leak.
If this helped you, please leave me positive feedback.

 

It could be a dirty throttle body or FITV issue even if the IACV was changed. I would also check the PCV valve and battery/ground connections since bad grounds can cause idle dips on these cars too.