Pwnmeister

iTrader: (1)

I drive a 96 civic hatchback with a b16a2 swap. My car's idle was perfectly fine and then I changed the oil. This time I changed the oil to 10w-30, I was using 5w-30 before. Ever since the oil change, the idle became weird. It would idle at 900 at neutral but it doesn't fluctuates. (This is when the car is parked)
If I step on the gas pedal a little or rev it a little, the RPM goes up as usual then drops back 900, but the weird part is it doesn't stay still at 900. Instead it goes up to like 1200 rpm and then it will idle back at 900 rpm. After that the idle won't fluctuates, it'll stay at 900.
The only time that weird idle problem happens is when I step on the gas pedal or when I'm cruising and put it in neutral.
Hope you guys understand the situation.
I researched a bit and many says there's not a huge difference between 10w-30 and 5w-30.
I know changing the oil grade will most likely not cause this problem but I just wanted to include it since it was the last thing I did before the problem occurred

EDIT: the CEL code is P0505

Solved: Found there was an vacuum leak on the intake manifold. Ended up being for the cruise control.

thirsk66

iTrader: (2)

Sounds like you need a new Idle air control valve or your throttle cable might be too tight or loose, or vice versa. Id check those two things out first and go from there.

motegicivic

Not the oil.

The 10 means it is thicker at startup that is all.

How does it run otherwise?

Former User

Try bleeding the cooling system.

Pwnmeister

iTrader: (1)

It runs fine. Just the idle is acting weird
Well, I drove it a bit last night to see how the car runs, right when I parked the cel turned on. Scanned it and it's my iacv. So I hope the problem will go away once I change it

Pwnmeister

iTrader: (1)

Any recommendation on what brand I should be looking at for a new iacv?

GarageNut

Not a huge Honda guy but still am a technician. I've had the TPS sensor fail and cause this problem on many cars. Is weird that it happen right after oil change seeing that wouldn't cause this.

thirsk66

iTrader: (2)

well are you buying a brand new iacv or a used one? I have two of them in my tool box that are good ones let me know if you want one. and as far as that guy saying your tps might be the blame for your problem, plug in your scanner and scroll down to live data to TPS% and it should be at 9.0% which I think it already is at.

Former User

An IACV code does not necessarily mean the IACV is bad. First clean it and test the two wires for power and ground.

thirsk66

iTrader: (2)

agree RonJ@ht knows his stuff better then anyone, definatley test your iacv right now and go from there no sense in replacing a good part

Pwnmeister

iTrader: (1)

Ya I was planning on cleaning it first before spending the money on a new one.
When you say test the two wires for power and ground, do you mean if there's power going through them?
Thanks

Pwnmeister

iTrader: (1)

Update: took off my iacv and cleaned it using carb cleaner. Sprayed it continuously till there was no dirt coming out. Let it dry and installed it back on
I couldn't find the bleeder valve for the coolant so I just opened the radiator cap and turned the car on along with the fan on set to hot. I left the car on till it reached operating temp (about 16 mins)
My attempt to get rid of the air inside the coolant was by squeezing the hose.
Please let me know if that's the wrong way to bleeding it or where the bleeder valve is at for a b16a2.
I also cleaned the throttle body using tb cleaner and a tooth brush
Deleted the code, car drove fine and idled fine for like 100 miles then right when the cel went back on. The car kept jerking a lot at low speed and when I let go of the gas pedal. Idle jumped up to 1500 rpm
The bad idle and car jerking goes away once I turn off the car and turn it back on. But the problem happens again after like 5-10 of driving.

What else should I do next?
I heard you could tell if an iacv is bad by unplugging it or something. Someone clarify.
Thanks

(the cel code is P0505)

Pwnmeister

iTrader: (1)

Bump, When the car was fully warmed up and idled at 1500. I unplugged the IACV, the idle dropped down to 1000 rpm.
I actually recorded a short vid, i'll try to upload it.

also, I tried covering the port in my TB but the only port i have is the upper port which I assume is for the IACV.
What is supposed to happen when I cover that port?

Pwnmeister

iTrader: (1)

bump

Pwnmeister

iTrader: (1)

Anyone?

Pwnmeister

iTrader: (1)

bump

Former User

Tell us about the engine swap. For example, what ECU are you using?

Have you checked for a vacuum leak?

Have you used the service manual procedure to adjust the idle speed?

Have you tested the ECT sensor and the TPS?

Pwnmeister

iTrader: (1)

The swap is just a stock b16a2 swap. Nothing was modified like internals or whatever. Simply a b16.
I have been trying to find a vacuum leak. What ways do you suggest in finding them? I also found this weird plug that's sitting behind the intake manifold (driver side). I believe it's missing a plug to it because there's a hissing sound and if I plug it up with my finger, my car dies out. I will upload a pic tmr morning

I have looked into adjusting the idle but I haven't yet because when the car is normal, the idle is at 900-1000. But when the bogging and jerking stuff happens, the car will idle at 1200 or 1500. And when I try to gas it a bit, the idle will jump up and down between 1500-2000. Causing the car to bog/jerk if I try to drive.

Can you show me how to check the ect sensor? I checked the voltage on the tps when it's plugged in. I used a voltmeter and probed the middle wire, I believe it was red and black. The voltage was ~.52 closed TB and ~4.61 WOT

Former User

What ECU?

This^ is the cause of the idle problem. That's the vacuum nipple for cruise control. It needs to be blocked or capped because it's allowing air to be sucked into the IM and this is screwing up the idle control. The engine dies because the idle speed has been down adjusted to compensate for the vacuum leak.

How to fix idle problem:
1) Block off nipple to eliminate vacuum leak.
2) Adjust idle speed as per service manual instructions (see FAQs sticky).

TPS voltage is fine.

Pwnmeister

iTrader: (1)

Okay. Does it matter what I use to block it off? It'll be awesome if I could see a pic of how it should be.
So I should block it up then adjust the car's idle? But the car dies right when I plug it up.
I'll try though.

Former User

There's no one right answer. For example, you could find a rubber cap that fits tightly over the nipple to block it off. Just rig something that won't leak or get sucked into the IM.

omerfar23

How did you fix the leak after you found it? replace the hose? tighten it?