Possible stopped up cat?

[Pat K.]

I posted the other day about a rough idle and power loss. I replaced the plugs, wires, and plug well seals. It seemed to run better for a couple of miles after the tune up then it lost power again.

When I ran the cylinder balance test the first 3 cylinders it killed seemed to make more of a difference (You could feel more of a dead miss). The last 3 you could also feel the miss but it wasn't as noticable. My balance test passed.

It was suggested that one thing to check was for a stopped up cat. Does anyone know the order the balance test goes in? What I'm trying to say does it check say the front bank (radiator side) then the rear bank of cylinders, or do they criss - cross like on many V8s?

I was thinking that a stopped up cat say off one engine bank would cause the balance test to act like it did.

Any input would be appriciated

 

[Mr Anonymous]

Search under 'leaf blower' and 'broom' for ways to check the cats. Also, have you verified the timing to be correct?

 

[DavidT]

nope. My sho dyno'd at 99 max HP oh_my . I ran a cylinder balnce test and it passed. I finally found the culprit... a huge restriction in my exhaust caused by a previous owner who "tried" to gut the cats!
The biggest symptom the restriction caused (besides the power loss) was that at WOT, the rpms did not increase with ease and speed past 4K. However, outside of that, there were no other symptoms, it idled fine, etc...
The test that let me find the restriction was disconnecting my y pipe and going for a spin. It was extremely loud, but as fast as a beast! (My restriction was downstream from the cats)
If your cats are stopped up, Midas can do a backpressure check (by inserting a meter in a small hole in each cat). You will get a definite answer, and will only cost around $20 max.
Good luck! And welcome to the forum!

<small>[ February 16, 2003, 08:57 PM: Message edited by: dkautumna ]</small>

 

[AutoSHO]

Pat K.:
Does anyone know the order the balance test goes in? What I'm trying to say does it check say the front bank (radiator side) then the rear bank of cylinders, or do they criss - cross like on many V8s?

I was thinking that a stopped up cat say off one engine bank would cause the balance test to act like it did.

Any input would be appriciated

Yes, it goes in order like this:
Firewall
1-2-3 - Rear Bank
=====
4=5=6 - Front Bank
Front of car

If you said that it seemed much less noticeable for the last 3, it could indicate a plugged cat also. it would be the cat from the front bank in this case. At the speed the balance test is run at it may not have been enough of an obstruction for the computer to pin-point any one cylinder.

 

[BlackMagik]

I just found a bad cat on my car this week. The symptoms I've had are power surges while cruising at constant throttle, poor fuel mileage, and the easiest one to identify was a marble in a coffee can sound coming from under the car at idle. I took mine to a local shop and had it put on a rack, you could actually shake the y-pipe by hand and hear the stuff inside of the cat rattle around. I took the cat off today and cut it open and sure enough the honeycomb material inside of it was eroded enough so that it actually turned cross-flow and blocked off the exhaust on that bank. SUCKS! I'm hoping I can weld new cats on in the straight section of the exhaust and pass emissions so as to avoid buying a new ATX Y-pipe!!!

Hope this helps!

 

[Pat K.]

Wow, those symptoms sure soulds like whats going on with my car.. the rattle and the surging.

I'll have to admit I'm at a bit of a loss as to how to set the timing on this car. First car I've owned that doesn't have a distributor

Thanks again for the help!

 

[sdpatt]

Possible stopped up cat? Give the kitty some Ex-Lax.

Sorry, I couldn't help myself.

<small>[ February 17, 2003, 10:07 PM: Message edited by: sdpatt ]</small>

 

[Mr Anonymous]

Pat K.:
Wow, those symptoms sure soulds like whats going on with my car.. the rattle and the surging.

I'll have to admit I'm at a bit of a loss as to how to set the timing on this car. First car I've owned that doesn't have a distributor

Thanks again for the help!

Do you have the Ford shop manual? It covers the timing in detail, but real quick you can put the timing light on the #5 cylinder and pull the SPOUT shunt located between the CID sensor and EEC test connector to force base timing. I actually think this might also be covered on the emissions labels under the hood.

 

[AutoSHO]

sdpatt:
Possible stopped up cat? Give the kitty some Ex-Lax.

Sorry, I couldn't help myself.

Hahaha! thumbs_u