Leviatard

Hello Honda-Tech Family, I require some assistance. Its been almost 2 months since I have completed this swap and aside from this annoying issue the car runs great and is has some nice pep. But this high idle problem remains. It will Idle at 1500 - 2300 while warming up and continue until I drive it for a long time, and then it wont idle normal until I come to a complete stop. It will not idle normally like it used to when you disengage the clutch. Now the things I have done to try and solve this include:

-Cleaned the Throttle Body (I used the D16Y7 Throttle Body due to the IACV)
-Cleaned the IACV
-Made sure there are no vacuum leaks
-And made sure throttle cable slack and throttle rocker were properly adjusted

What else is there to do to try and fix this issue, would this have anything to do with the Idle adjust screw on the throttle body itself? What are your guys experience with this? As always, any help is appreciated!

Former User

Car?

ECU?

CEL codes?

Leviatard

99 honda civic, D16y7, z6 intake manifold, y7 ecu, no codes.

Former User

There's a diagram in the FAQs sticky on how to adjust the idle speed for your engine. Follow the instructions without deviation. You'll need an external tach or an OBD2 scan tool that reports live data.

Leviatard

Well idk how that would help considering the Z6 Intake manifold on it now so it would need alteration, the other thing I notice is that when it does idle normal, if I just let it roll in neutral once it hits about 15-20km/h the idle shoots right up to 1500-2000 then if I slow it below that it drops back to normal...my issue may lie in whatever causes that.

Bently_Coop

Either try a different IACV or replace it.

Leviatard

So the IACV would be causing that?

HondaPartsHero

Did you cap off the cruise control nipple on the back of the Z6 manifold?

What throttle body gasket did you use?

Leviatard

I used a y7 TB gasket, and the cruise control nipple on the back is being used for evap purge

Leviatard

Also another thing I should have mentioned is that when i first completed the IM swap I accidentally got the MAP and TPS plugs mixed, would that of possible damaged either sensor?

Leviatard

ALMOST FIXED IT
it idles normal now when warmed up, i adjusted the back end of the iacv tht little plastic thing, anyways, now the last thing is the idle picking up when the car starts rolling, and I have found that no matter what I do to calibrate the tps its always off voltage. now would that mean its gone bad?

tony_2018

Have no idea what you mean by adjusting idle on the backend of the iacv, I'm not even sure how you are calibrating the tps and its still not calibrated properly.

Leviatard

Its fixed the TPS was fuckered, way out of voltage range. I changed it and its good now, and to calibrate the tps you loosen the two rivet screws (which I changed to bolts) and you rotate it forward or back when the throttle is .5v closed. i was getting a lowest of .66.

tony_2018

I find it weird that all you did was move the throttlebody over and your tps was out of adjustment. But anything can happen.

Leviatard

That wasn't what damaged it, it was when I had accidentally put the map sensor plug on it and its plug on the map and started it, that was when I first did the intake swap.

Leviatard

So to be safe I replaced both the MAP and TPS and made sure not to mix their plugs and bam, runs like a charm now.

tony_2018

Bud, nothing was damage, it was out of spec. As you stated in your post you had to adjust the TPS sensor back to .5v. But its a good thing you had spares.

Leviatard

yes it obviously was if trying to put it back to spec by calibration and couldnt get the voltage back to .5 its lowest was .66 with the throttle plate out. i was also told by multiple sources that you have to be careful not to do that since the MAP plug carries more of the voltage than the TPS plug does. i was lucky to have a spare that way I wouldnt have to scour a junkyard. but hey all I care about is that its running properly now and doesnt idle at almost 2000 RPM

the ghoul

A bit of an old thread but I have run into this same issue and have a little information on the subject.
I have seen multipul people resolve this same issue by re-adjusting or replacing the TPS but what wasnt brought up here, that I find very interesting is there are a few reports that if you are running the 3 wire IACV you must run the "automatic" style TB gasket or else you will have a massive vacuume leak.
Lastly I have seen in a few cases people have installed both the stock y7 3 wire IACV and left the 2 wire z6 IACV on the back side of the intake, basically what was happening is they would run one of the IACVs and the non-functioning one was allowing air to flow thru it causing a vacuume leak.
Just thought Id throw these out there incase anyone else (like myself) stumble on this thread trying to troubleshoot their issue