Cats/Thermactor - Not a delete ???

[backfocus]

How do you tell if the cats are clogged?

I have been working on a problem for awhile now for a code 94. The code is for the passenger side smog system, this I know. I have tested all the smog valves, vacum selinoids and computer grounds, all are ok. I did find problems with the smog hoses two were cracked and have since replaced them temporary until I can find the pre-formed hoses. Anybody know where to find new hoses? Ford discontinued them, I currently used a straight peice and bent it, but it is to close to the headers.

I don't know how to check the "check valves" that go to the exhaust, chilton say to just visually inspect them, well they look fine. But I am still getting the code 94 and it still makes a rapping noise (like backpressure). When you take off the hose that attaches to the check valve for the cats there is some backpressure that comes out back from the cats. Is it supposed to do that? Or is the check valve bad or the cats clogged or both?

 

[795.0]

If the cats are clogged, it would be down on power, especially in the upper rpm's. Get a friend to snap the throttle a few times while you check for good flow from both tail pipes. (not too close you'll burn your hand) Most modern cats are made with a wire screen coated with a catlyst and clogging is'nt as much of a problem as it was with the early pellet type. To inspect the check valves, remove them and try to blow through each end. If they're OK, air will flow in only one direction. They stop hot exhaust gas from getting into the AIR pump, hoses, and valves, yet allow air to go into the exhaust to help burn leftover fuel.

 

[willys1]

Could be the cats.I just took off the factory H with 4 cats,they were definitly clogging because of the performance gain!Summit sells high flow cats for 50-60 bucks.

 

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I had read about pulling out the O2 sensor and hooking up a pressure guage from the hole to the pass. compartment, then driving to see if the back pressure goes above 4psi. Also read about a vacum test on the engine. Rev it up and if vacum drops 7 or so the cats are clogged. Anyone done these kinds of test, do they work??? Seems like it wouldn't run right with the O2 removed anyway.

As for the check valve it must be bad because there is exhaust coming back out of there from the cats. Will have to cut it off, and replace because it is one long pipe back to the cats.

I don't know if I have factory cats, I know the mufflers back are borla. But I do have 4 cats.

Any ideas on where to buy new smog hoses?

 

[trbkrb]

I have codes 94 and 44, for both sides and have not been able to fix it yet. I did the same, replaced the valves and solenoids with good used ones and checked all the hoses and nothing looks wrong. If you have 4 cats, they are most likely stock. Most aftermarket use just 2 cats.

As far as the hoses, you can try to find some good used ones, but who knows how long they will last. I got a set free from a friend's race car, so it was no big deal. I wonder if heater hoses would work, say from some other car?

Good luck and let us know if you find anything out. I still have to get mine to pass inspection.

 

[jrichker]

Codes 94 & 44 - AIR system inoperative - Air Injection. Check vacuum lines for leaks, & cracks. Disconnect the big hose from smog pump: with the engine running you should feel air output. Reconnect the smog pump hose & apply vacuum to the first vacuum controlled valve: Its purpose is to either dump the pump's output to the atmosphere or pass it to the next valve. The next vacuum controlled valve directs the air to either the cylinder heads when the engine is cold or to the catalytic converter when the engine is warm. Disconnect the big hoses from the back side of the vacuum controlled valve and start the engine. Apply vacuum to the valve and see if the airflow changes from one hose to the next.
The two electrical controlled vacuum valves mounted on the rear of the passenger side wheelwell turn the vacuum on & off under computer control. Check to see that both valves have +12 volts on the red wire. Then ground the white/red wire and the first solenoid should open and pass vacuum. Do the same thing to the light green/black wire on the second solenoid and it should open and pass vacuum.

Remember that the computer does not source power for any actuator or relay, but provides the ground necessary to complete the circuit. That means one side of the circuit will always be hot, and the other side will go to ground or below 1 volt as the computer switches on that circuit.

The computer provides the ground to complete the circuit to power the solenoid valve that turns the vacuum on or off. The computer is located under the passenger side kick panel. Remove the kick panel & the cover over the computer wiring connector pins. Check Pin 38 Solenoid valve #1 that provides vacuum to the first Thermactor control valve for a switch from 12-14 volts to 1 volt or less. Do the same with pin 32 solenoid valve #2 that provides vacuum to the second Thermactor control valve. Starting the engine with the computer jumpered to self test mode will cause all the actuators to toggle on and off. If after doing this and you see no switching of the voltage on and off, you can start testing the wiring for shorts to ground and broken wiring. An Ohm check to ground with the computer connector disconnected & the solenoid valves disconnected should show open circuit between the pin 32 and ground and again on pin 38 and ground. In like manner, there should be less than 1 ohm between pin 32 and solenoid valve #2 and pin 38 & Solenoid valve #1.

If after checking the resistance of the wiring & you are sure that there are no wiring faults, start looking at the solenoid valves. If you disconnect them, you can jumper power & ground to them to verify operation. Power & ground supplied should turn on the vacuum flow, remove either one and the vacuum should stop flowing.
See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host)

http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif

http://www.veryuseful.com/mustang/tech/engine/images/88-91eecPinout.gif


The definitive check for the check valves is to remove them and attempt to blow air through them by mouth. They will pass air freely one way and block airflow the other way. Not neat and clean, don't tell your wife or G/F you've been kissing the exhaust on your Mustang. If you do, you may get to sleep on the couch. :

 

[backfocus]

Thanks jrichker,

I was hoping you would chime in on this problem. I have followed all the tests on the Smog system that you had already posted, just didn't see anything on the check valves. Everything else is good.

I will be replacing the one that goes to the cats. But here is a question have you heard of any of the tests that I wrote earlier for checking about clogged cats. I am wondering because if they are clogged I would think that would cause failure of the check valve. Just wondering.

Replacing the check valve.

Will post my results.

 

[jrichker]

The Chilton Service Manual has a check for restricted exhaust system using a vacuum gauge. I don't remember the details, but I will try to read up & post them later.

 

[backfocus]

OK!!! So I changed out the check valve on the tube that goes from the smog system to the cats. as it was leaking backpressure. Thought it fixed it, but no.

Still get it (code 94). It sounded great, no rapping noise until it really warmed up. I even pulled the second valve vacum hose, so air would go straigt to the cats while it was warming up and it didn't make the noise then. Only when it started to get real warm did the rapping noise begin.

I am thinking one of 2 things now. The cats are clogged or my oil leak on the passengers side valve cover has something to do with it. I talked with a local shop (recommend) and they have a pressure test to determine condition of cats. Think I might go on the weekend.

Any other suggestions???

 

[backfocus]

Went to the muffler shop today and had them check the cats. Cats are in good shape not clogged.

If anybody wants to know a muffler shop trick for checking the cats out here it is. Drill a small hole before the cat. In the hole place,tightly, a small air fitting with a slip on adaptor. Get a 0-10psi pressure gauge with a hose attached and put it on the adapter. With vehicle at operating temperatures, start it up and then have someone rev up the engine. Watch the gauge it should be 2-3 psi. If you have anymore than than there is some sort of restriction.

As for my problem, not sure where to go form here?