View Full Version : Is this a plugged cat(s) symptom?? Did I kill them running cold??

Mike Manzo
11-12-2002, 01:15 PM
Over the past couple weeks I have experienced a little bit worse gas mileage. Yesterday the car would act boggy off the line and I noticed that the vaccum was off by maybe 3 in. Immidiately I thought I was sucking air into one of the (Ford dealer) crappily sealed intercooler tubes.

Not a big deal, it was only a couple inches, right???

Well, by the end of the day the car was running like it had a huge cam in it and the vac dropped below 10in in drive and it just would not accelerate at all.

I thought it was the fuel pump since I have experienced similar effects when one went bad in another car I owned. After hooking up the fuel pressure tester, the fuel was AOK.

My mechanic says the cats are plugged and I think this is my fault. I think that my fan settings that have been keeping the car running at 195 max degrees has caused the car to run like it does at cold start and I have been building up carbon in the cats.

Sounds like a valid theory, but I would like to bounce these symptoms against the SCCOA crowd to see if anyone throws up a flag about it.

Keep in mind that this is a 6 month old exhaust system, new cats, etc. There are no codes being thrown and no noticable engine noises or damage that I can tell. The problem came on relatively suddenly and "progressed" as opposed to just broke.

I am assuming that I should have done more with the eec tuner to compensate for the cooler running situation other than the fan settings. In the back of my mind I knew that this could be an issue with burning too much fuel, but I thought I would experience carboned plugs or something minor...I didnt think I'd nuke my cats.

Any other theories???



11-12-2002, 09:55 PM
does car get hot ? does it clear up at w.o.t. if so its not cats cloged cats will make yopur car not rev freely, it runs hot its gutless, pings usually will idle good but not work right when revved up, vacuum will be good at idle, sounds more like you've got ic tube leaks or bypass sticking open or leaking bypass hose, check em out. the bad idle says intake leak.

David Neibert
11-13-2002, 01:09 AM
I agree with Manny, it sounds like a vacuum leak. You can run the engine a cool as you want and the cats are going to heat up from the hot exhaust gas.

Spray some carb cleaner on the IC tube connections. If there is a leak it will suck the cleaner into the engine and you will hear a differince. If you have a raised top the upper IC tube sits a little crooked where it attaches to the intercooler and is much harder to seal with the teflon.

I got tired of resealing mine and started using the Permatex Copper (orange) RTV. No more leaks..ever.


XR7 Dave
11-13-2002, 12:26 PM
Ya, don't worry about temperature affecting the cats. Look elsewhere.

XR7 Dave
11-13-2002, 12:26 PM
Ya, don't worry about temperature affecting the cats. Look elsewhere.

11-13-2002, 09:41 PM
I think when your cats get plugged, boost jumps considerably do to the increased back pressure. When mine went bad the boost went up to over 15lbs (under hard acceleration) if this is not happening its somthing else. More than likely a vac leak