Hello. Recently, my car has expirenced a large loss of power at WOT after 5500 rpm when hot after longer drives(highway) power is normal in cooler conditions and short city driving. Just replaced plugs, problem continues. Side note: my CAT converter warning light came on a few times when temperatures fell below 40 degrees. Any suggestions before I cut open my welded exhaust to check for a clogged cat?

Thanks guys.

1991 na Fc
81000 miles

 

If you're getting the exhaust over temperature warning look there first(fix this quickly, that's not good). If the cat is failing it could be clogged up and choke the engine on top end. Pull the cat and inspect it, possibly throw a test pipe(temporarily) on and see if that helps(you're in florida anyway). The other thing that can make EGTs really high is retarded ign timing, you could make sure the CAS is lined up correctly pretty quickly. Seems unlikely but never hurts anyway.

 

I would go with a clogged cat if the warning light is coming on

 

Okay I'm going to a shop tomorrow to get it cut out and a test pipe put in.

 

Took it to my shop to get a cat less header made, popped open the hood to find the smog pump had cracked off the block. Seeing how that would have been removed anyways, I'm not exactly upset.

 

Not having the air control valve pumping fresh air into the exhaust for the cat could definitely kill the cat much quicker. Make sure you really seal a block off plate well for the air control valve, the are prone to leaking(vac leak).

 

I plugged everything up so there is no leak. I'm waiting for parts to make the header. I'm trying to not drive it far

 

You need to smog pump to actuate the VDI and Aux ports on the S5, not having the smog pump functioning is what caused to power drop, removing it will not fix the issue.

 

I thought it just sends air into exhaust?

 

On most vehicles, yes.

On 7's, they do more than that

 

On the S5 N/A specifically it is what is responsible for opening the VDI and 5th & 6th ports. All the other years and models the smog pump can be removed.

 

Okay I need to fine myself a new air pump bracket without getting raped on price

 

Try the classifieds on this forum.