Paid SVOboy a visit!

[GasSavers_TomO]

ok, good. The things I can think of that would cause a vacuum leak:

1. intake manifold gasket (if the manifold has ever been taken off)
2. Fuel pressure regulator and the line running to it
3. Charcoal canister solenoid and line
4. EGR control (black box) system
5. EGR line/diaphram
6. IACV
7. Throttlebody gasket (if TB was ever removed)
8. PCV system
9. Incorrect aftermarket gas cap installed or OEM gas cap not turned until it clicks

Those are the things I can think of off the top of my head. I know you probably checked all of those though. Just kind of thinking out loud.

[SVOboy]

I didn't think of the gas cap, I checked everything else, and neither the tb or im seemed to have ever been removed. I was rather perplexed.

[GasSavers_TomO]

Yeah, the gas cap can actually cause a vacuum leak through the vapor system being active. It's just that the OBDI computers aren't quite good at catching that as the OBDII ones are.

But yes, very perplexing that the vacuum leak exists still. But according to Holmes, if all other possibilities have been removed, then the remaining, no matter how ridiculous, must be true.

So maybe the ECU is at fault?? unless we are both just missing something so obvious that we should slap ourselves in the head.

[SVOboy]

I'm fairly sure it is a physical leak based on several symptoms including the revs not dropping quickly. I plugged every physical hole I could and the engine still ran, the air must have been coming from somewhere.

Also, when replacing the pcv valve, it ran properly for about 5 minutes and then went back into it's old habits, which further confused me...

*sigh*

[GasSavers_TomO]

ok, two more things I just thought of

• Was the hose from the intake manifold to teh PCV valve collapsing?
• Was the throttle plate stop screw messed with at all? The little set screw under the throttle body stop tab.

[SVOboy]

It wasn't collapsing, seemed in good condition. Pinching it would mess drop the idle though, which is how I diagnosed the PCV valve (also took it out and blew on it).

The mechanic said the idle screw was messed with, but to me it didn't look like it. However, it is possible it was and the plate was being held slightly open, which would make sense...a lot of air was getting in...

[1993CivicVX]

Sorry, fell asleep. hehe. Took an impromptu nap. So, yeah, there was a very happy but very brief time when the engine idled at 500rpm. Was a thing of beauty. But then it went back to roaming and random. All the mechanic said was that the "throttle body was tampered with" and I think he pointed to the coil when you push that thing down to give it throttle. But maybe the screw--I don't know heads or tails when it comes to cars. Will be going to the mechanic in a few minutes to find out if all ended well!! Hopefully he won't be still scratching his head when I get there and will have figured something out. Thanks guys for batting this one back and forth.

[1993CivicVX]

Mechanic thinks there are no vacuum leaks. Umm... it just occurred to me if he's been looking for the last two hours and not found anything, I owe him $120 for nuttin?

[SVOboy]

That's why I've never taken my car to a mechanic,

[panamacolin]

nothing=nothing...I say you buy him lunch and call it even...