Goat-4-sale

Hello everybody, new member here. I recently got myself a 1999 civic dx with 150k. But now I recently been going through alot with it.

Now before i start l, i know how vacuum leaks are a much talk about subject and how new posts with it are annoying. Yet i gotta since I searched alot!! And cant get an answer to mine so forgive me.
So I recently started having a nasty idle last week. Upon start up the rpms start bouncing up and down. They will not go away or ease up at all. I bought a new throttle body, intake manifold gasket, throttle body gasket and bled the coolant. Checked every hose possible by blowing in it and covering the other end.

Now i figure its a vacuum leak since when i put my hand over the throttle body the engine doesn't stall. Yet i tried looking every hose possible. My code is a P0505. Does anybody any ideas?

ezone

Which engine and which trans?

Does it slow down at all?


Engine running and warmed up to operating temperature:
Is the IAC valve screaming hot? It has to have good coolant flow through it.

Look in the throttle body and plug off the open ports with your fingers. Does it slow down or stall? Quit surging? Idle normal?


TPS reading correct at closed throttle?
ECT accurate?

Goat-4-sale

I believe its the standard d16y6 non v-tech.

Yes after i cover the throttle it sounds like it's supposed too.

For the tps reading ill post the results tomorrow as i do not have the tool with me

ezone

Look in the throttle body and plug off the open ports with your fingers. Does it slow down or stall? Quit surging? Idle normal?

Tap on the IAC valve several times with a tiny hammer or a screwdriver handle while the engine is running, see if that brings the idle speed down. It's quite likely to be stuck wide open.

Goat-4-sale

Thanks for the advice ezone. I tried and it would not change it. I should add that when i spray brake cleaner around the iacv it surges as if its the vacuum leak but I closed the crap out the screw. Some even snapped on me. I too added silicon around it but nothing. Ugh

Would you happen to know where the pcv hose is connected to. Thats the only hose connected to the manifold that would allow it to get airflow to

And yes. Only after i plug those holes would it quit surging and idle normal. Doesnt stall

ezone

Engine running: Unplug the IAC valve wiring. Does the RPM increase or decrease?

Does this have a manual trans or automatic trans?

Goat-4-sale

It increases and the surging gets alot quicker rate.
It is a manual transmission

ezone

Flow chart in the service manual says...

check TPS-- approx 10% at closed throttle or 0.49v depending on how your scanner reads it

(NOTE: this flow chart assumes nobody has ever touched the throttle body, the stop screw has not been cranked open and nobody has ever touched the TPS.....so if anyone has touched it it needs to be put back the way the factory built it)
>
ECT on hot engine 194-205*F
>
Is idle speed too high? (yes)
>
Let engine idle, put your finger over the lower port in the throttle body
Does the RPM drop? (yes, but chart doesn't specify how much)
>
Adjust idle speed. If that is impossible, replace the IAC valve.


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I hope the pic of the PCV system was the right one for your engine.

Also look for a small hose or vacuum cap that would be on the port used for cruise control if it would have been equipped with it. I'm not 100% sure it would even have the port on a DX but it's something to look for.

Goat-4-sale

Yes that was a really good pic. Tomorrow i will look further into it. I got some new ideas and hopefully itll lead me to it. Big thanks ezone. Will update

Goat-4-sale

Update!!! So today i took my whole head off completely and put it back together. No luck. All that work for nothing.

I than said eff it!! I let my dogs out the yard to play. Than my pitbull starts chewing on the throttle body gasket. At first i disiplined him. As i put everything back in and turned on the car to move it, boom sounded normal!! I was like ok maybe the surge will happen any minute. 5 mins passed and nothing. For the final test I than put my hand over the throttle body and it shut off!! Im now wondering how the gasket did all this

ezone

You mean you took off the throttle body?

Maybe the IAC valve finally got unstuck.

Goat-4-sale

No i took off the gasket. idk about the iac since it happened with 3 of them.
Im thinkin it was a crappy gasket. It was a vacuum leak since it would stay on with the hand was on throttle body. Idk the name of the gasket but it was < $3 at autozone. Cheap pos