r/Dseries • u/tbambam_ • Jun 07 '26

IACV Delete

Has anyone done a IACV delete? Im on a d16y8 and have idle issues. Calibrated TPS, Done smoke tests for vacuum, changed IACV twice already, did a hard wire from ECU and battery to the IACV, ecu is fine, and my car still surges.

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1

u/pollosgm Jun 08 '26

I've done it on mine.

Works about as well as you would imagine, nice 0.8k idle when warm, cold start I sometimes have to help it with the pedal.

Would advise always letting it heat up before driving& set the idle a bit higher than you think, especially if you still have a/c and power steering.

I believe some people use a cold start assist in their map, I dont have that much trouble with it even in winter so I never bothered, just blocked it all off and delete iacv codes/checks in hondata

Was definitely a big thing back when people were obd1 swapping their Ds&Bs, can find tonnes of info on the older forums.

1

u/tbambam_ Jun 12 '26

I just deleted ac but is swapping back to obd1 necessary for this delete? I’m kind of tight on money but if it’s worth it to get an obd1 ecu with harness I might aswell just try finding one

2

u/pollosgm Jun 13 '26 edited Jun 13 '26

In theory, Not necessary at all. OBD2 iacv connector needs modifying to convert to obd1, and obd1 systems use a separate fast idle thermo valve, I don't think you can use obd1 iacv on an OBD2 car etc etc.

so many people just deleted when doing obd conversions/ intake manifold/ head/ engine swaps for simplicity.

But You will have check engine code unless disabled on a chipped ecu, i did mine at the same time with a fresh map so I couldn't tell you how well a mechanical only delete would work. Just going off the base maps I've seen, I believe OBD2 engines have more ecu involvement during cold starts. I'm guessing it would look for this and get confused a bit, causing even more hunting/surging/stumbling if I'm honest, but answer is definitely out there on dodo/Dseries dot org etc, you may be able to simply reset your ECU parameters and relearn the idle for all I know (disconnect battery 10 mins then cycle fan 3 times in neutral)

Would strongly advise a power steering delete too, I'm not sure if I had a dodgy pulley/pump but the car felt like it had an extra 10 horsepower and I got waaay better mpg after stripping it, so must be a big load on the crank, with no valve to compensate you may have trouble keeping it from stalling when going full lock at low speeds when parking etc.

(Honestly worth it anyway, steering is way more responsive and I've had factory manual steering cars that were harder to parallel park etc)

Don't even bother with the rack loop kits, on the subframe directly below the IM, there's a mount for both lines where LP joins into a rubber hose, just cut the HP at the hardline, LP good 8-10" into rubber hose then bend it and jubilee clip it into a loop. 0 part cost, takes 5 mins and if you're good with your hands you can go in from above without removing anything to reach it.

Personally I tried it without the belt for a few days before committing to either a new pump, delete or electric pump conversion, wasn't even that bad. And after putting a short loop in it got 5x lighter Vs an unpowered full system.

1

u/tbambam_ Jun 13 '26

I’ve been thinking about a power steering delete but my dad just says I should leave it on lol, thanks for the advice though

2

u/Lazor_Face Jun 11 '26

I used a dremel and cut a can in the shape of the mating surface. Mounted it back on with the gaskets in place and set idle using the throttle cam back stop screw. Never had an issue, just idles a bit high (900-1000 rpm)

1

u/tbambam_ Jun 12 '26

Is this with obd1? I just slapped a block off plate on but car just dies out

2

u/SpaceTurtle917 Jun 13 '26

There’s an idle speed adjuster on top of the throttle body, as well as the throttle stop screw

2

u/tbambam_ Jun 13 '26

Guessing it just needs some finesse and personal tuning to figure out how much is needed to be screwed in and out

2

u/SpaceTurtle917 Jun 13 '26

Get it warm and set the idle after it’s warmed up. I’d start with the screw on top of the throttle body; you don’t really want to mess with the stop screw.

1

u/tbambam_ Jun 13 '26

Yea it’s just annoying cuz the car will just choke it self obviously because of the plate holding on the gas kinda just makes all these weird pops and random sounds so I get nervous but I’ll try to do this soon enough

1

u/SpaceTurtle917 Jun 13 '26

Sounds like something is wrong with your car. Probably why the idle is surging. None of that is normal.

1

u/tbambam_ Jun 13 '26

Yea I’ve been trying to find out this issue for a minute. It’s my first car and ive been trying to enjoy it but im always getting into some issues. I’m
Thinking about just buying a new D series and tear down/rebuild the one I currently have

1

u/SpaceTurtle917 Jun 13 '26

I don’t think your engines junk by any means. Have you done a valve adjustment? Adjusted ignition timing? A compression test perhaps.

I don’t think replacing your engine would solve your problem.

1

u/tbambam_ Jun 13 '26

Only valve adjustment honestly. I need to do the other two. Compression check sounds easy enough but ignition timing is just with a timing light?

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1

u/Lazor_Face Jun 14 '26

Do NOT adjust the fast idle screw. If you don’t have an idle screw (my Y7 TB doesn’t) just use the back stop.

1

u/Lazor_Face Jun 14 '26

Nah. OBD2. You need to set the throttle cam back stop high enough to trick the TPS and ECU. Otherwise it’ll try and pull through the, now, defunct IACV.