Hi

​​​​​​Can anyone please guide that what voltage reading should be obtained for 3 wire IACV?? While engine on and also KOEOff

I am having hunting idle of my car between 1500 RPM - 2500 RPM due to IACV its confirmed.

I did Voltage tests

1- KOEOff and got battery volts on middle wire and the other 2 wires i got continuity with battery negative terminal while the connector was not connected to solenoid.

2- Now connector connected with solenoid did same test while engine running idle again got battery volts on middle wire and on other 2 wires i am getting 7.5 volts on both wires.

3- while engine on and running when i unscrewed the solenoid and remove it from IACV without disconnecting the connector from solenoid my idle becomes totally normal.

So i want to know if the 12 volts are fine on middle wire and 7.5 volts on other wire while engine running are also perfect?

Because i think i have some issue with my wiring harness or ECU because when took off the solenoid the idle got perfect and smooth. So there must be some issue some kind off short circuit or maybe bad ECU which is sending abnormal signal/volts to IACV.


Please expert assistance required badly. Getting very bad mileage from my civic.

 

Are any CEL codes thrown?

Have you cleaned the IACV and bled the cooling system?
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Electrical:

1) Unplug the IACV connector.

2) Turn key to ON(II).

3) You should read ~12V to body ground on the pin for the Yel/Blk wire.

4) You should read ~0V at the other two pins.

 

@mullersfan - Thanks for your reply mate....

1- No CEL codes and light is off.... but CEL turns on throws code for sensors if any connector disconnects from sensors while engine running, then when we connect it back turn off engine and again turn on engine then CEL goes off automatically.

2- Yes while key on engine OFF i am getting 12.5 volts on 1 wire of iacv connector which is middle wire and other 2 wires having 0 volts and showing continuity with battery ground.

3- Please feed me in simple words how to bleed the cooling system as i am not at all a tech guy and technical terms flies over my head
i just bought this car before sometime my technical knowledge was zero but now i think this car will teach me alot LOL... !

 

Few clicks of my engine ecu and iacv for better suggestions

 

Have you removed the IACV and cleaned it with brake or carburetor cleaner?

Bleeding cooling system:

1) Begin procedure with a cold engine.
2) Top off radiator and reservoir with coolant.
3) Set heater lever or dial to max heat so that heater hose valve on firewall is fully opened. The cabin blower need not run during bleed procedure.
4) Loosen radiator cap but do not remove it.
5) Start engine and let it idle until the radiator fan turns on and off at least two times. This may take 20-30 minutes.
6) Turn off engine, and again top off radiator and reservoir with coolant, if necessary.
7) Tighten radiator cap.
8) Done.

 

instructions well noted for bleeding system.
Thanks again @muellersfan

yes i have cleaned the iacv with carburetor cleaner and its like new now from inside.
i have posted my engine and other pictures before this comment but admin has not approved it yet i think.
@admin as i am new here in this forum/webiste IDK if you are real admin or not but if you are then please approve my comment with pictures attached.

 

TomCat should be able to help you out.

 

Unplug the IACV and check the resistance of the two coils inside (terminal 1-2 and 3-2). I don't have the spec but I think it's on the order of 20 ohms. Mostly you're looking for open circuit. Also there should be no continuity from any terminal to ground.

This is assuming no codes are in the ECU. If the CEL is on for any reason, resolve it before trying to chase an idle problem.

If you have an OBD scanner with live data capability, watch the coolant temperature make sure it is consistent and over 180 F when warmed up. If the ECU thinks the engine is cold it will command it to idle fast. The coolant temperature sensor (ECT) can be tested with an ohmmeter. Knowing what the temperature is, compare its resistance to the chart in the service manual.

A couple more thoughts on bleeding the cooling system:

Park on level ground or facing uphill before starting. You may read of heroic efforts to raise the front of the car with jacks, I don't think that is necessary but definitely don't be facing downhill. The radiator must be the highest part of the cooling system when bleeding.

If there's a lot of air in the system start the engine (cold) with the radiator cap off and keep pouring coolant in as necessary to keep it full. When the radiator starts to overflow because the engine is heating up, put the cap on tightly and make sure there is some coolant in the expansion tank. Then idle or drive the car until it is fully warmed up, and park on level ground or facing uphill again and wait until it is completely cold. Then repeat the process if necessary.

 

thanks for joining in @mk378 i dont have the OBD scanner
but i will do the bleeding thingie tonight and can you please tell me what reading should an ohmmeter spit out lets suppose the coolant temp is now @180 F what should the ECT resistance now and if you can also share some link for complete service manual of d16y7 & d15b also.

also tell me about the continuity with battery -VE terminal which i am getting on the connector side 2 wires of IACV is while KEY ON ENGINE OFF and while the engine is running when i take off the solenoid the race settles down and car idles smooth + while engine on 7.5 volts on side 2 wires while connector connect to solenoid. readings were taken by inserting a needle from behind the connector one by one on each wire on sides.

i also reckon that the previous owner has swapped the engine from d15b to d16y7 but did not entered the new engine number on car registration book instead of that he has forged the the old engine number on new engine. i doubt this too. and the ECU currently is for d15b but the engine is d16y7. all this in my own thinking and dobut. as on the engine where the engine number is found there i can clearly see as if someone has buffed or grind that area to forge the old engine number on the swapped one. i willl share those pics too later.


please fellas help me and take me out from this thing as i dont have much technical knowledge

 

Solved now pictures are approved now and are shown. IDK who did it but yeah you can see now in my earlier comment.

 

Did you complete the bleed procedure?

With the engine fully warmed up, you should measure 200-400 Ohms between the two pins of the unplugged ECT sensor located below and slightly forward of the distributor.

For the unplugged IACV, you should measure 16-28 Ohms between the middle pin and each outer pin individually.

If those Ohm readings are fine, then do the idle adjust procedure for D16Y7 engine below.
Note: It is critical to monitor the engine idle speed with an external tachometer as the cluster tach is useless at low rpms.

 

Are you sure you don't have a leak in that make shift intake? I would try finding a OEM intake asap that does not look like its sealed properly at the top.

 

I don't believe that an intake air system leak would affect the idle speed. Maybe you can explain your thinking.

 

His hunting idle! a intake/ vacume leak can cause a hunting idle.

 

As the air intake system is upstream of the throttle body, it cannot cause a vacuum leak. In fact, if you completely remove your air intake system, the engine will idle normally. You need to do more reading about how an engine works.

 

well butterfly or throttle itself makes vacuum leak and let the air flow inside the engine sorry but i have to agree with @muellersfan on this

and that's really sweet of you mate for such a lovely offer i will surely consider it if needed (y)
Cheers. My main culprit is IACV which is not acting properly its not closing properly after the engine is fully warmed up.

 

did that but no luck

Did this after engine fully warmed up fan turned off on 2 3 times then measured resistance and got 200 ohms on it

Got around 24 ohms between pin 1,2 and 2,3

Can i post a video here in this thread? I have made a video today with solenoid attached and detached from iacv while engine running. So if i can upload it here please advise

 

Yes, you can.

Do the idle adjust procedure next.

 

Well i think idle adjust is better to be done while ecu scanner attached so live rpm is there in the scanner instead of attaching a tachometer.
Your thoughts?

 

That's how I do it. Do you have scanner that reads live data? If not, you can also use a multimeter that is able to read frequency.

 

ummm well not really i dont have a scanner but a tech guy in a workshop nearby has it.. will go to him tomorrow for this .... i am now thinking to buy one really + i am uploading video now in next comment please do watch it.... if i dont get any issue in uploading it

 

You would generally upload the video to a video hosting service (e.g., YouTube) and then copy-paste the share link into your post.

 

doing this now for sure because having trouble in uploading it here directly.

 

there you go mate

 

Anyone there to comment on video??
or everyone out for weekend fun ?