CEL P0505
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CEL P0505
Hey Guys,
I just recently bought a 98 Honda Civic. D16y8, 5spd bone stock. It’s a super clean car but when I bought it, I bought it knowing the alternator was over charging at 17 volts. I drove it one day, just to test it and make sure everything was good. Sure enough the battery started smelling like Sulphur. So I swapped out the alternator and battery.
The next day, half way to work my CEL came on and it started idling around 1500RPM. If I lightly pressed in the gas, the idle would surge from 1500-1575ish very fast, but if I gave it more gas, it would stop.If I took off from a stop, it would jolt/hesitate until I gave it more gas to start going. As I go through gears, if I let off the peddle, it jolts, if I gave it gas, it jolts.
If I turn off the car, and restart it. It’s fine for about 5 minutes and starts doing it again. I noticed it takes about 10-15 minutes of driving for it to start happening. The CEL doesn’t go off either. The code reader is saying it’s P0505 (Idle Control Valve). I know it can be a number of things, but I was wondering if this exact thing has happened to anyone else, and what they did to fix it?
Before the idle starts up, it usually idles around 800-1000 RPM. Sometimes it will go to 1500, but drops back down.
So far, I’ve only checked:
TPS (Voltage gradually goes up and down, but I haven’t done this test yet while the vehicle is doing it)
Burped the Coolant, (the coolant was bubbling for awhile but stopped for the most part, it still does a little).
Also did an idle re-learn and drove it for a half hour, got on it a few times and was fine, but the next day, it started again.
Thanks in advace!
I just recently bought a 98 Honda Civic. D16y8, 5spd bone stock. It’s a super clean car but when I bought it, I bought it knowing the alternator was over charging at 17 volts. I drove it one day, just to test it and make sure everything was good. Sure enough the battery started smelling like Sulphur. So I swapped out the alternator and battery.
The next day, half way to work my CEL came on and it started idling around 1500RPM. If I lightly pressed in the gas, the idle would surge from 1500-1575ish very fast, but if I gave it more gas, it would stop.If I took off from a stop, it would jolt/hesitate until I gave it more gas to start going. As I go through gears, if I let off the peddle, it jolts, if I gave it gas, it jolts.
If I turn off the car, and restart it. It’s fine for about 5 minutes and starts doing it again. I noticed it takes about 10-15 minutes of driving for it to start happening. The CEL doesn’t go off either. The code reader is saying it’s P0505 (Idle Control Valve). I know it can be a number of things, but I was wondering if this exact thing has happened to anyone else, and what they did to fix it?
Before the idle starts up, it usually idles around 800-1000 RPM. Sometimes it will go to 1500, but drops back down.
So far, I’ve only checked:
TPS (Voltage gradually goes up and down, but I haven’t done this test yet while the vehicle is doing it)
Burped the Coolant, (the coolant was bubbling for awhile but stopped for the most part, it still does a little).
Also did an idle re-learn and drove it for a half hour, got on it a few times and was fine, but the next day, it started again.
Thanks in advace!
Last edited by Bodiedon4s; May 14, 2018 at 08:35 PM.
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Re: CEL P0505
Start by disconnecting negative terminal from battery.Then remove the IACV and clean it along with it's gasket screen with brake cleaner spray. Also, remove and clean the throttle body. You may need to replace the throttle body gasket as well and if so use a Honda genuine (OEM) only.
After cleaning and installing the throttle body use a bit of WD-40 on the throttle body blade (butterfly) and blade shaft to lubricate movement.
Inspect and adjust throttle cable per service manual.
Before reconnecting the negative battery cable inspect all grounds to chassis and engine for tightness and debris.
Also, turn off all electronics because you will want to do another ECU reset (idle learn) after reconnecting negative battery terminal.
Concerning coolant have you noticed any drop in radiator coolant level combined with gain or excess coolant level in yhe reservoir?
After cleaning and installing the throttle body use a bit of WD-40 on the throttle body blade (butterfly) and blade shaft to lubricate movement.
Inspect and adjust throttle cable per service manual.
Before reconnecting the negative battery cable inspect all grounds to chassis and engine for tightness and debris.
Also, turn off all electronics because you will want to do another ECU reset (idle learn) after reconnecting negative battery terminal.
Concerning coolant have you noticed any drop in radiator coolant level combined with gain or excess coolant level in yhe reservoir?
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Re: CEL P0505
Brake cleaner doesn't work worth a ****. Sprayed, rinsed, soaked, dumped and repeated several times with brake cleaner until I was confident that no more carbon and gunk was coming out of my IACV. Spent a few hours doing this on a Saturday. Then on Sunday I gave it another go with simple green and it was like I never even touched it on Saturday. So much **** came out, I couldn't believe it. Let it dry, installed on Monday and it idled smoother than ever.
Honda-Tech Member
Joined: Jul 2017
Posts: 230
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Re: CEL P0505
Brake cleaner doesn't work worth a ****. Sprayed, rinsed, soaked, dumped and repeated several times with brake cleaner until I was confident that no more carbon and gunk was coming out of my IACV. Spent a few hours doing this on a Saturday. Then on Sunday I gave it another go with simple green and it was like I never even touched it on Saturday. So much **** came out, I couldn't believe it. Let it dry, installed on Monday and it idled smoother than ever.
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Joined: Jan 2014
Posts: 991
Likes: 2
Re: CEL P0505
Yeah brake cleaner burns your skin, which is a pain in the *** and I couldn't imagine it being too great for paint/rubber seals/plastic etc... I would still use it if it worked better, but from what I have seen simple green works better and has none of the disadvantages either.
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Re: CEL P0505
So I haven’t been able to diagnose it yet, I’ve been super busy, but here’s an update about what it’s been doing. The other day I was driving and I noticed the CEL turned off. I was driving around, the car was fine, didn’t do anything. Then it turned back on for another day. Then it did it again, CEL turned off, drove fine and then came back on. Pretty weird? Going to get to it this weekend.
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