ScottyBobby

The y7 in my 96 civic blew, so I ordered a obd2 d15b from hmo for a cheap replacement.

Its wired in with a p72 and the y7 harness. Both vtecs work fine, but theres a really bad idle surge.

I was told to get a y8 throttle body, and the wires attached and wire it into my harness to stop this problem.


This is such a technical problem, and an uncommon motor, and I'm entirely unsure where to start.

Advice?

ScottyBobby

Anyone have any advice?

Another issue I forgot to mention, the gas pedal is almost like an on/off switch.

HondaPartsHero

Did you wire the IACV from 3 wire to 2 wire? Any check engine lights? Clean the IACV/FITV

apexi_rsx

needs to be converted from a 3wire iacv to a 2 wire iacv as posted above. i dont understand why your running a p72 ecu unless its chipped for running a d15b

ScottyBobby

The butterflys from the p72 are set up to trigger the economy vtec.

Could a z6 tb have a 2 wire tb and work in place of a y8 tb?

apexi_rsx

2 wire IACV would be located on the intake manifold not the TB alone. you need to be running a z6 intake manifold or a Manual transmission y8 manifold. i know auto manifolds still have the spots on the manifold where the 2 wire iacv can go. you could drill it out and tap for the 2 12mm bolts that hold it in.i wouldn't be too fond of this idea unless u have some mechanical skills.

djslim23

Yeah what he said, you just need an intake manifold off of a manual D-series. Since you're running the p72, you won't need the EGR found on the d15b's. M/T z6 or y8 would be your best bet.

spdzne4dr

^^^^agreed about 2 wire iacv. i would suggest y8 manifold

ScottyBobby

I have the jdm d15b manifold that came with the motor from hmo.

Apparantly thats the same as the y8 manifold, but the iacv is below the tb.

Im so confused.

djslim23

3-wire IACV = Automatic
2-wire IACV = Manual

I'm pretty sure you have the 3-wire. So you need to find an intake manifold out of a M/T car. I'm pretty sure all Manual IACV's are on the intake manifold, not the TB, so you'll have to swap the whole thing.

djslim23

some info on my thread might be able to help you
https://honda-tech.com/forums/honda-civic-del-sol-1992-2000-1/jdm-d15b-3-stage-p2j-ecu-egr-o2-sensor-wiring-checklist-pics-2802636/

apexi_rsx

if the IACV is on the bottom of the t/b then you have a 3 wire iacv and u need a 2 wire iacv. your ecu is looking for a 2 wire iacv and u do not have one. you need a manual Intake manifold with a 2 wire iacv. so it all needs swapped

ScottyBobby

Everyones right.

I have an automatic d15b intake manifold

Ill be putting the z6 intake and throttle body on later this week and wiring it for the 2 wire iacv.

Thanks for the help everyone.

ScottyBobby

okay, so I got a z6 manifold today, and I noticed theres a plug on top of the d15b tb that has no place on the z6 manifold, and a plug on the back of the z6 manifold that doesnt match up to the wiring harness.

Im guessing the plug on the tb is the egr?

djslim23

Yeah the d15b vtec has an EGR, but since you're not using the d15b's ECU, you don't need the EGR. As for the plug on the back of the Z6, is that the 2-wire IACV? You need to find a 2-wire IACV plug for it if you haven't already.

ScottyBobby

Ill find a good way to connect my harness to the plug. I may end up just solering it.

And I realized the other extra plug is the cruise control, which I dont have, so its all good.

djslim23

I forget if the plug you need is male or female, but you might want to use quick disconnect connectors rather than soldering it so you're not stuck like that.

Like these

titi_vtec

if it is below tb is A/T you should find a M/T intake manifold with M/T TB from a Y8 engine that came 2 wires, just put it and do the stuff with the wires and problem solve

ScottyBobby

That ^

I'm guessing the z6 manifold will bolt on in place of the automatic d15b manifold? Aside from the iacv conversion?

djslim23

Yep it should be easy, vacuum lines might be a little different, but not too bad.