FITV questions

[RLong31]

So I've been updating parts that have been neglected on my 89 LX-i lately, and after doing a tune-up, and installing a new brake master cylinder... I noticed an erratic idle in park/neutral. So... I cleaned the IACV. Then it was idling very high at around 2000 rpms. So... I adjusted the idle screw on the throttle body.

Now, I hear a very loud hissing coming from the engine. It hisses a little bit after I turn the engine off too. I checked all the vacuum lines I could visually.. and sprayed some throttle body cleaner on them as well and found nothing. I then put my ear to it... and I'm pretty sure it's my Fast Idle Thermo Valve.

I took it out, and cleaned it. Didn't help. So... looking at new one at O'Reillys, it's $72 and I have to special order it from BWD. From the little reading I've done, it seems to be a very common problem? Is it something I can get from a junk yard and clean/use.. or get off e-bay for $25? Or is it something I want to get brand new?

Any help/ advice is appreciated.

Thanks :)

[cygnus x-1]

Sounds like maybe you have a leak in the brake booster. Try unplugging the vac line to the booster at the intake manifold and plug the manifold port and see if that fixes it.


C|

[Demon1024]

how did that gasket look on the IACV when you took it out?
Did you replace it?
On the fast idle you can try turning it all the way down ( it wont high idle when cold ) and turning it up on a cold start. Or block it off completely for the same effect.

When you look into your intake with the filter off and look into it you'll see 2 holes on the backside towards the firewall. Put your finger over the top hole without getting your hand sucked IN!
I believe the top one was fast idle and bottom one was supply for Iacv. Plugging the one for the fast idle should lower the idle when engine is cold and do nothing when the car is warm. If you plug the one to the Fast idle there with your finger when it's warm it should do nothing. If it decreases idle then try screwing down the Fast idle and see if that fixes it

[RLong31]

Sounds like maybe you have a leak in the brake booster. Try unplugging the vac line to the booster at the intake manifold and plug the manifold port and see if that fixes it.


C|

Did this... and it fixes the hissing sound as long as my finger is there or that intake hole is plugged.

Now... I tried replacing the hose already.. even thought it looked fine, except for being a bit hard, but otherwise... no holes to speak of. Even with the new hoses.. it still hisses. Checked all vacuum lines around it, and they are fine.. even sprayed everything with throttle body cleaner again.

What the hell is going on?

[RLong31]

Well, I found the issue. Where I replaced the brake master cylinder.. on the bottom side of the master cylinder where it contacts the brake booster was not making good contact for some reason? I put my finger over it, and it stopped hissing.

I tried to loosen the master cylinder and push it down a bit and re-tighten. Didn't work, so... I came up with a temporary solution until I come up with something better or I get paid again, lol.

I put some High temp, rtv silicone gasket sealant around the edge of the master cylinder. Now... I didn't think it would be a good idea to start it up with wet silicone on it, so I am letting it cure overnight, and we will see if that fixes it.

If it does.. I'm leaving it until it causes a problem again.. if it doesn't fix it... any other suggestions besides replacing the brake booster?

[Dr_Snooz]

I think you're going to be replacing your booster soon.