I have a 89 RX-7 GTUs and a weird hissing noise started on the left side of the engine below/behind the air pump. I noticed that it went when the exaust fell of the manifold but that could be because i couldnt hear it. Also i lost all power...

 

Lost all power as in horsepower/torque, or power as in electricity? How did the exhaust fall off of the exhaust manifold?

 

I lost HP/Torque and the exhausted fell off because the nut fell off the stud

 

it sounds like a small muffler leak

 

how is that affecting the engine bay?

 

It would explain the hissing noise and loss of power. (I believe zaidnew meant exhaust leak.)

How did the nuts back themselves off of the exhaust studs? Do you keep maintenance on your car?? If not, it's a good time to start. Be sure the gasket from the first pre-converter to the exhaust manifold is still useable, then bolt both sides tight.

 

The car won't lose power if the exhaust has a large leak or is removed altogether.

And way to reply a year later.

 

I would think there would be at least a bit of power loss. (We are talking about HP/TQ, right?)

And I believe his most recent question was posted 2/7/2012.

 

They need the back pressure I'm sure

 

I was thinking vaccume leak but an exhaust leak sounds right

but wouldnt you lose power (hp/tq) with a vacumme leak?

 

The power has been the same because i noticed a complete separation after the cat on the exhaust so i just took it off. Also i thought it was a vacuum so i changed the lines and there is still a hiss that i cant resolve. COuld it be gasket on the manifold?

And i replied later because i was busy with work girlfriend etc. lol So i bought another POS for the time being

 

I also hear like a hissing / pingy noise near that area after i removed the ACV and airpump.

 

Oh, I didn't realize the separation was AFTER the cat. I thought it was a large separation immediately after the manifold... In which the O2 sensor would receive a bogus reading, causing the car to run rich. This would give the car a "sluggish" feeling.

IF all vacuum lines are good... Check anywhere that there is a gasket. You said it is behind/below the air pump. Perhaps the exhaust manifold is loose on the engine. Are the air pump hoses "good" ?

 

Are you sure you don't have a exhaust plugged .. sounds like the exhaust is building pressure Remember the old potato trick in the exhaust ? it gave every symptom you have .. Just a thought

 

The cat was clogged so that is why im thinking the gasket blew. but now im just trying to find out what i need to replace

 

Replace the cat and associated gaskets.

Check out the FSM -> 1989 Fuel and Emissions Control Systems (non-turbo)

 

awesome thanks