Plugged Pre-Cat?

coreylubahn · Post by **coreylubahn** » Mon Mar 14, 2005 7:21 am

HJ,

I know that after I got my exhaust done that you recommended that I keep an eye (ear) on my pre-cat because they can easily become plugged. Well I'm thinking that maybe this is happening. The first road trip I made after my mod-a-palooza (including the exhaust and HPIII) I got something like 20 MPG and had a nice sounding exhaust. Now I am getting like 17 MPG and the exhaust doesn't seem as loud all the time. I'm having a hard time deciding whether I've just got used to the exhaust but it's still the same, or if maybe my pre-cat is becoming plugged. The exhaust does seem louder at cold-start (any time it's been sitting for a while), but after driving a bit it seems quieter again...is this normal or could this indicate some kind of problem? The mileage drop definitely doens't seem right, but admittedly it was fairly windy on the last couple of trips, but could wind really cause a 3 MPG or so drop? Just curious as to what you think since you've had this problem. Thanks!

Post by **HenryJ** » Mon Mar 14, 2005 5:37 pm

HenryJ wrote:On the return trip and I guess, a little noticeable while pulling the hills on the way out for the extended memorial day weekend, the intake noise started to noticeably increase while the power decreased.

The temperature did rise a little quicker than usual, spark knock over 4000 rpm began to get worse.

Today it would barely make 50 mph, bogging the whole time.

The mileage drop can be attributed to many variables.

Cat plugging has several symptoms:
Increase in temperature when accelerating and warms up quicker than usual, Loud intake that makes that BWAHHH sound went you accelerate, Bogging and spark knock or pinging. All of this gets worse as it warms up.

If you have all of the above...your plugged.

bwenny247 · Post by **bwenny247** » Mon Mar 14, 2005 6:01 pm

beyond normal driving wear and tear, what causes the precat to clog?

is it attributed to mods done to the engine/exhaust....or just a natural thing that happens over time?

jeggers · Post by **jeggers** » Mon Mar 14, 2005 8:13 pm

what causes that never herd of it befor???? Can someone explain please.

Post by **HenryJ** » Mon Mar 14, 2005 8:20 pm

You really need to read the original thread- Plugged Pre-cat

HenryJ wrote:Here is a site that shows some of the damage and causes of converter failures-
Magnaflow website - converter failure