I have a 99 Civic EX a few weeks ago I was driving around and randomly while switching gears my car started jumping like it was going to stall out (I later found out that if the car goes below 1500 rpms it starts doing it). While idling it bounces from 1500-1600rpms constantly but when driving above 1600 rpms its fine. I pulled over and immediately and turned it off. I tried starting it after a few minutes of looking in the engine bay for anything obvious and it wouldn't crank. So I checked my battery and the ground cable was frayed. I replaced the cable on the spot with a new one and it fired right up but still had the surging problem. I went to autozone and got it scanned and recieved a P1509 code. I removed the IACV it looked dirty inside and seemed to be stuck, At the time I couldn't clean it because the sensor screws were stripped, so I ordered a used Y7 throttle body from ebay. (The previous owner had a Y7 TB on there before) The new one looked good I cleaned it and I did an olms test on the sensor. Tried starting it and no luck, I even tried the whole used TB and again no luck. I learned later after a bit of searching that you should do idle resets when messing with the iacv and tb so i did, again no luck still surging nothing changed. I searched all over the forums and what i think might be my problem is some wiring issues but im not experienced enough to make the call on what my problem might be. I went ahead and did a wiring test using a Y7 99-2000 AT guide (The previous owner swapped this ex from AT to Manual) I know the guide is for a y7 and i have a y8 but with a y8 tb i figured it might work and correct me if wrong. All wires are in the same place on my ecu as the guide so idk.

My battery has 12.47 V
Below im gonna list my readings in order with the guide i post (DTC P1509 is indicated so we will skip that) after that ill list everything in steps
So "Check for an open in the wires [Pg lines] will be step 1
Step 1: Body ground-B2= 16.3 mV Body ground-B10= 16.1 mV
Is there more than 1v? - No
Step 2: Body ground-B6= 10.81 V Body ground-B15=12.12 V
Is there battery voltage? - Not fully so idk
Step 3: (checking IACV) Terminal 1-2= 21.1 ohms Terminal 2-3= 20.8 ohms
In between 16-28 ohms? - Yes
Step 4: Terminal 2- Body ground 12.27 V
Is there battery voltage? - Yes
Step 5: Terminal 3- B6 = 24.7 kohms Terminal 1- B15= 57.8 kohms
Is there continuity? - Yes? im not sure if kohms counts
Step 6: Body ground- B6= 26.1 kohms Body ground- B15= 4.06 kohms
Is there continuity?- Yes? again im not fully sure what to make of this

I would really appreciate if anybody can help me follow what my problem might be because what i have found from this is i either need to take my harness out and inspect said wires in the guide or try a new ECU and if you guys think its something else please let me know what else i should check, Thanks

 

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bump

 

Was the IACV on the new “used” TB in good shape?

 

Yes, it was way cleaner than the one that was on my car originally. No rust on valves, gasket was good and just clean overall, I opened that one up and cleaned it before installing aswell.

 

Doesn’t matter how it looks, matters if it works or not. It very well might not be working either.

 

I did an ohms test on the terminals and it was good to go, are there any other ways for me to check if its working properly?

 

Not without a proper way to set up a PWM since that is how they are controlled through their full range of motion. You can apply direct 12v+ to the valve to make sure it even moves.

if it doesn’t move, well then it’s broken.

 

Okay so I tried hooking the iacv to direct 12v which was my battery (read 12.6V) but I was getting sparks. I watched a video of a guy doing it on youtube and he said a battery would work fine. Idk what this means. thank you for the replies if you could maybe send me a guide for a pwm or something like that it would be greatly appreciated.
Ive also learned the ecu in my car right now is an automatic ecu with a auto trans delete in the motherboard (the guy who sold me the car told me) im wondering if this could be causing the problem as well.