'96 Taurus catalyst efficiency problem.

Hello,
My sisters Taurus has been throwing fits lately.
Some days it surges while driving. This morning it just refused to restart without some help from the pedal.
I recently pulled off a P0430, Catalyst efficiency below threshhold, bank 2.
This sounds like either a cat or an 02 sensor. What I've read up on so far, it sounds like the cat.
I've heard in the past, that "cat's don't just die. They're killed."
If I swap out the cat, would it also be wise to go for the 02 sensors? I'm worried the one(s) on the manifolds are telling lies, causing the poor running/starting.
So... If so - All of them? How much do they run?
Thanks, -marc
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Marc Westerlind wrote:

Also,
Should I just find a cheap replacement cat and weld it in, or go for the full $350 Y-pipe setup, which includes both cats?
Thanks, -marc
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Marc Westerlind wrote:

I think i would do the O2 sensors first, check for codes, then evaluate the situation. Not cheap either, but cheaper than cats. You can always reuse them on the new cats if you really need them.
Bob
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do with your running problem. Sounds like the car needs a tune up or some other problem not related to that code. I would start with plugs and a fuel filter...... If you do wind up getting a CAT for it, go to a muffler shop and have them put one on for about $100.
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===One more thing, O2 sensors have NO affect on cold startup.

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Scott M wrote:

That's true...
What are the parameters for 'cold startup'?
Yesterday it refused to start back up after it was already sitting in the driveway for 20 minutes, warming up. It was about 45*F outside.
What I'm worried about, is that the manifold 02 sensors are not accurate... sending wrong info to the computer... which is putting a wrong A:F ratio into the engine. An overly rich mixture will kill a cat, correct?
I'm worried that if I don't look into what caused the cat do crap out, it'll happen again with the new one.
The engine has been gone through as far as tune-up stuff goes. Wires, plugs, fuel filter, air filter, all that fun stuff. There are no codes on the computer anymore...
The car has 140K miles on it. The only thing new to the car is a valvetrain, a battery, and the above mentioned parts.
Do these engines have distributor caps? I didn't get a chance to really look at the square thing.
Thanks! -marc
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I believe it is more likely there is a problem in the closed loop system, forcing the F/A ratio controller to operate outside of its design parameter thus contaminating the 02 sensor. Have it diagnosed by a system analyzed and correct the fault, WBMA. Something as simple as a bad plug wire can eventually contaminate the cat and the sensor
mike hunt
Marc Westerlind wrote:

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start condition, cold or hot or anything in between. There is no dist cap. Besides the check engine light and code for ineffecent cat, the only problem is it seems hard to start? Please explain exactly what you mean....You said you have to give it a little pedal and it will fire right up? Earlier you said it surges a little? please explain exactly. With that many miles on the car it wouldnt hurt to change the front O2 sesors, but it wont fix your starting problem. Also with that many miles on the car the CAT is probably bad, even if nothing else is wrong. Yes a rich running condition or a miss will kill the CAT prematurely. If it is hard to start but a little pedal will get it going nicely, start by cleaning the throttle bore if it is dirty and clean the IAC too.
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Scott M wrote:

Correct, I should have caught that...

Distributorless... easy enough. I didn't recognise it.

Sure -
Both of these problems both popped up in the last week. The code was about a week and a half or two weeks ago.
While driving, fully warmed up, at random times, the engine will surge or stumble a bit. I couldn't get a more detailed explanation, or take the car out myself.
The other morning, the car was idling in the driveay warming up, for about 20 minutes. My sister shut the car off, and went to restart it a few minutes later. It did not want to start like a normal fuel injected car should, with a simple turn of the key.
She gets on the phone and calls me. She tried a number of times to start it with just the key. I'm lost as to what to tell her. I fall back on the method on starting an old carbed engine, and tell her to tap or modulate the throttle a bit while turning the key. If that don't work, put the pedal to the floor and try it.
She came back saying that it started with a little throttle.
I haven't been able to catch up with her for the last few days to check out the car any further.

That sounds good... thanks.
Just wanted to make sure the running/starting problems weren't tied in with this.
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Usually on a newer Ford, a small, intermittant miss while on the highway, slight accel, it is a plug wire/plug.

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Look for small vacuum leaks. Read the plugs on that bank.
Marc Westerlind opined in

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