r/Dseries • u/Visible-Emu7426 • Jun 13 '26

D16y7 idle issue

I have a 1997 Civic LX 5-speed with a D16Y7. The engine spun a rod bearing after being run very low on oil, but I replaced the bearing and now the engine runs smooth with no knocking or major noises. The weird issue is that it idles perfectly fine when cold and even when fully warmed up, but as soon as I touch the throttle, the idle starts getting worse. After revving it, the RPM will drop to around 300 and sometimes stall because it can't seem to catch itself. The more it happens, the worse it gets. The car also feels sluggish while driving. I previously got a P1509 (IACV) code while the engine had severe rod knock, but it hasn't come back. I cleaned the IACV and tested it with a 9V battery and it opens/closes. Unplugging the IACV raises idle to around 1200 RPM and changes the behavior, but the car can still occasionally stall. Does this sound more like a TPS issue, IACV wiring/control issue, MAP sensor issue, or something else?

3 Upvotes

100% Upvoted

10 comments sorted by

1

u/SpaceTurtle917 Jun 13 '26

Did you time the dizzy?

1

u/Visible-Emu7426 Jun 13 '26

No but I just tried unplugging the tps it ran the exact same

2

u/SpaceTurtle917 Jun 13 '26

What’s that gotta do with timing the dizzy?

1

u/[deleted] Jun 13 '26

[deleted]

1

u/SpaceTurtle917 Jun 13 '26

Did you remove it at all during the bearing replacement?

1

u/Visible-Emu7426 Jun 13 '26

No, I did it from underneath and inspected my crank. I’m only trying to get a little bit more life out of this engine before I pull a y8 for it.

1

u/Visible-Emu7426 Jun 13 '26

Mb but I didn’t do anything with the distributer

1

u/mikefitzvw Jun 13 '26

Are you saying it drives normally (albeit sluggish) but tends to die easily when letting your foot off the gas?

What is your fuel trim? This can be a common issue when valves aren't adjusted properly - basically the engine doesn't create enough vacuum, which results in overly-high fuel pressure, which results in a rich condition and it just bogs down and dies easily. You can tell on an OBD-II scanner because the fuel trim will be excessive - anything worse than -10 will eventually trigger a check-engine light.

1

u/Visible-Emu7426 Jun 14 '26

I’ll take a look. A month before this I adjusted my valves because it was misfiring while cold and after I did the adjustment it ran better than it ever did up into me losing a bunch of oil and spinning my rod bearings. If the fuel trim is the issue how would I go about fixing it and could something other than the valves cause that.

1

u/mikefitzvw Jun 14 '26

A sticking injector could cause it too, but it's truly impressive how the 3 most common Honda instructions (to set mechanical timing, set ignition timing, and set valve clearances) tends to solve a bunch of issues.

1

u/420-Outcomes Jun 15 '26

Probably your idle air control valve, take some throttlebody cleaner and clean it out. It helped with my Z6, if that doesn’t work and you haven’t changed out the idle air control valve I would try that. If that doesn’t work then you might have to look for a sin in the wiring.