94preludeguy

Couple weeks ago, a friend and I did a Y8 head swap into my car. Once everything was finished and done, I had a nasty idle surge from 1k to 2k RPMS and my check engine light is on. I've searched for a solution and haven't had much luck. I have cleaned the IACV and even tried a different one with no luck. I got the car scanned today with the CEL the guy told me a few different things. Map Sensor, Throttle Position Sensor and EVAP something. I'm not concerned about the EVAP code because I doubt that's related to the idle surge. Anybody got any ideas? I really don't want to buy new sensors and have that not be the problem.

vanste

try reversing the harness on the TPS and MAP, that might help...

94preludeguy

We marked the TPS so that wouldn't happen. But I guess I could always try it.

94preludeguy

Can anyone help me?

94preludeguy

Jimster480

what did you change when you did the minime swap? Did you change your manifold and throttle body or what?

Former User

What year Civic?

94preludeguy

What do you mean? It's a mini-me swap. So the head, intake manifold, throttle body.. was all swapped over.

Ron - The car is a 1996.

Former User

Just to double check.

The three wires that connect to the MAP sensor are YEL/RED, RED/GRN, and GRN/WHT.

For the TPS, they are YEL/BLU, RED/BLK, and GRN/BLK.

If the MAP and TPS connectors are not swapped, then uncouple the connectors and inspect both sides for any damage or moisture. Also inspect the wires.

94preludeguy

I haven't gone in depth to inspect the wires yet, but when I unplug the TPS while the car is running, the surge goes away and it idles steady around 1400rpms. Could this be a sign of a bad TPS? And how do you even remove the TPS? I was thinking about switching the TPS from my Y7 throttle body to the Y8 and see if that does anything.

Former User

The TPS is worth looking into. It should output about 0.5V with the throttle closed and about 4.5V at WOT.

94preludeguy

The TPS and MAP sensor are correctly wired. Tonight, I put my finger over the hole in the throttle body that I believe goes to the IACV and it stopped surging. So is it my IACV? I have tried a different one and also tried cleaning this one. Could the wiring have anything to do with it? I think we switched the two wires on the two-wire plug for the IACV to further diagnose problems.

This is such a pain in the ***. Everyone must think I'm trying to race at stoplights cause of the damn surge.

Jimster480

sounds like iacv

hondamark35

is the ECU in that list?

94preludeguy

Yes.. I'm running an OBD2a P2P. Will be running a chipped P06 whenever I can afford to convert o VTAK and get a conversion harness. Or I might just sell both of my P06s and buy a P28. I am planning on boost later so I will be getting the tuning stuff knocked out early.

villaninblack

Try changing your pcv valve with a new one.

hk_gsrguy

sounds like the fast idle thermo valve.... which hole in the throttle body you cover top or bottom? top iacv bottom fitv.... does it do it all the time cold start and after warm up?

civic_driver

I don't think the 96 civic has a FITV.

hondamark35

no fast idle thermo valve on the Y8... it's all controlled by the IACV.

to the OP: to get the true issue fixed, you need some troubleshoot flowchart time... check out hondahookup.com. if you're not a member, register. you can go to the manuals page and download a PDF for the 96-00 civic. in it you should be able to find a specific set of instructions on what to do.

Jimster480

u sure it doesnt? then what is the thing on the bottom of the y8 manifold that has a coolant line going into it. Pretty sure thats FITV.

civic_driver

On the 96-00 I think the coolant lines go to the IACV.

hondamark35

maybe on a Z6 manifold... but not a Y8 from the factory.

the Y8 automatic has the IACV on the bottom of the TB, same as the Y7's IACV. i do believe the Y8 has a pair of hose...bung, barb, nipple... whichever, but it's just a flow through to the IACV on the back of the plenum.

Jimster480

oh alright. Ya i have an auto IACV since i converted my car lol.

xddrfr3akx

if you swapped throttle bodys with one that has vtec than it has a FITV (fast idle thermo valve) and the vaccums need to be routed through that to the IACV...if your using a vtec intake manifold then your IACV is going to be on the back of the manifold not under the throttle body (non-vtec ek's) unless the head came off an auto y8 you will nee to convert the IACV plug and re-route the vaccums to run a FITV. also which injectors are you running...it can make a difference

Z3120

Check to see if you have any vacuum leak. Also check the vacuum nipples on the intake manifold, make sure they are plugged off (lower left if you are look at it from behind).