Air leak frustrating!

[jprhome]

I've had this power robbing air leak for some time now up until about 2 weeks ago it would start and run fine but it started not wanting to start unless I cranked it over and gave it just the right amount of throttle and it would sputter to life.

So I replaced the Plenum gasket with a Fel Pro gasket after scrapping the surfaces clean and torqued everything to spec
I replaced all the vacuum line hoses while I was in there.

I removed the TB, cleaned it and replaced the gasket also and torqued all the bolts down 13lb

I even chased the holes and bolts..

Still I get a loud hissing and horrible idle now, it idles like i a V8 Stroker almost.

Anyone got any ideas?

Just to throw it in there before disconnecting the vacuum lines i labeled them for there correct order

 

[KidVermicious]

Shoot a little starter fluid here and there around the plenum and vacuum hoses to find a vacuum leak. Be careful around a hot exhaust manifold.



Which is a thought, are you sure it's a vacuum leak? A bad exhaust leak upstream of the o2 can cause a bad idle.

 

[flyinhawaiian01]

Is it an air leak or just the sound coming from the throttle body?

Grab either a stethoscope, or if you don't have one, use a long vacuum line, put one side to your ear and while its running, poke around to see where the vac leak is coming from.

This also sounds like it could be the fuel pressure regulator, or even an exhaust leak.

Check for vacuum leaks first then move on from there if that's not the problem.

 

[wshiverick]

Shoot a little starter fluid here and there around the plenum and vacuum hoses to find a vacuum leak. Be careful around a hot exhaust manifold.



Which is a thought, are you sure it's a vacuum leak? A bad exhaust leak upstream of the o2 can cause a bad idle.

Correct me if I'm wrong but an exhaust leak upstream of o2 shouldn't cause it having a hard time starting right? It would cause bad idle but the computer should be going off of long term fuel trim when starting and the o2 should just be feeding data once it goes to short term fuel trim? Maybe after long enough the long term would be effected by an exhaust leak...maybe to figure that out disconnect the battery for a while and then see if it starts normally. I'd start with spraying the starting fluid around the intake tho like kid said and see if it revs up that seems more likely.

 

[wshiverick]

Also I'd say check/clean the maf but if you're hearing a loud hissing it must be an intake leak...

 

[jprhome]

Well I figured out the rough idle had a clogged line. but the hissing is still coming from right under the TB. I've gotten quite a bit of power back that I never had but that leak or whatever it is because even after spraying all over the area i got no change in idle or noise.

I did remove my TPS connector and nothing changed idles the same wether its in or not. bad TPS? no check engine light or codes.
I tightened my idle screw all the way and I'm still idling in park/neutral around 1300-1500RPMs

I've run out of ideas for today.

 

[The Count]

Do a google search for testing your TPS, all you need is a voltmeter. And as previously stated, use a can of carb cleaner to spray around the area you hear the vacuumed leak to help locate it.