This may sound like a Twilight Zone or Pet Cemetary plot, but I swear it is true!
My friend Jim has a 97 Taurus that he recently purchased used from the original owner Stacy. We are all coworkers so all of the history on this car is known. It has about 80k miles.
Around 40K miles, the check engine light came on with a catalyst efficicentcy code for bank 1. The dealer replaced the unique side input cat that there is no cheap universal cat replacement for. About $600 I think was the cost although I think the warranty may have covered it.
My friend Jim bought the car about 6 months and about 10k miles ago. Recently the bank 1 cat efficentcy code returned. He replaced the EGR module that can sometimes cause this code on a Tarus but it did not help. He did a complete tune up with the specified Motorcrap plugs and Furd dealer wires (FoMoCo ignitions are very finiky and may not run right with any other brand parts!!!)
Still the cat efficientcy code persisted. The bank 1 and bank 2 (left side and right side V6 engine exhaust pipes) O2 sensors were swapped. This is done to see if the problem moves to bank 2 or remains a bank 1 problem. It verifies whether the O2's are good or bad.
Now most brand's OBDII cat efficentcy monitors are looking at the O2's down stream of the cats and comapring the voltage swing to the upstream O2's. The upstream O2's should swing rapidly and wildly while in closed loop mode from say .1 volts to say .9 volts. This is because the unburnt fuel in each exhaust slug varies a little from the next. It is normal.
But the post-cat O2's should be much steadier and fluxuate slower and less wildly, from say .01 to say .7 Why? Because if the cat is working, it will reduce the oxegen in the exhaust stream as it breaks downs down the hydrocarbons and the result is a much less excited O2.
Now an O2 "simulator" could be used to get the car through emissions. These are illegal devices used by people who have modified their vehicles beyond what the law allows, usually to gain performance. My friend will not consider this as an option. ;~) Nor did he want to spring for the bolt-in factory-fit side flow cat pipe assembly from Walker for around $400.
On a whim, he started using FP in the car. Within a week of 80 miles a day highway driving the code was gone!
So he stopped using FP because that just can't be right. About 2 weeks and 2 gas tanks later, the code was back.
Again he used FP and again a week later the code was gone.
So he quit using FP because this is just a freakish coincidence, right? Well guess what? About 3 weeks and 3 tanks later the code returned.
Now what? More FP and wa-la! Within a week the code is gone. For 3 weeks as of this writing he has been on FP with no cat code!!!
My advice? Do this emissions test that he is required to do in August NOW!!! Now while it will pass!
Many questions remain.
Why is the 30k-40k mile cat going bad? Coolant poisoning? Carbon buildup? Poor design? Bad luck?
What exactly is FP doing to correct the problem with the cat if anything?
But the empirical evidence in this case is, not only will FP probably NOT harm a cat, but it may indeed revive a marginal one or one that that is dead or dying. Or the case could be that FP has cleaned up the emissions enough that that the marginal/dead/dying cat is no longer needed to perform at it its usual level of emissions reduction.
I strongly suspect that FP should extend the service life of a normal cat if used regularly based on this one odd example.
Here are two related threads that came up when I searched this site for similar discussions. Did I miss anything?
http://theoildrop.server101.com/ubb/ultimatebb.php?ubb=get_topic;f=5;t=002999#000000
http://theoildrop.server101.com/ubb/ultimatebb.php?ubb=get_topic;f=5;t=002238#000003
Any comments?
Thanks,
Mike
My friend Jim has a 97 Taurus that he recently purchased used from the original owner Stacy. We are all coworkers so all of the history on this car is known. It has about 80k miles.
Around 40K miles, the check engine light came on with a catalyst efficicentcy code for bank 1. The dealer replaced the unique side input cat that there is no cheap universal cat replacement for. About $600 I think was the cost although I think the warranty may have covered it.
My friend Jim bought the car about 6 months and about 10k miles ago. Recently the bank 1 cat efficentcy code returned. He replaced the EGR module that can sometimes cause this code on a Tarus but it did not help. He did a complete tune up with the specified Motorcrap plugs and Furd dealer wires (FoMoCo ignitions are very finiky and may not run right with any other brand parts!!!)
Still the cat efficientcy code persisted. The bank 1 and bank 2 (left side and right side V6 engine exhaust pipes) O2 sensors were swapped. This is done to see if the problem moves to bank 2 or remains a bank 1 problem. It verifies whether the O2's are good or bad.
Now most brand's OBDII cat efficentcy monitors are looking at the O2's down stream of the cats and comapring the voltage swing to the upstream O2's. The upstream O2's should swing rapidly and wildly while in closed loop mode from say .1 volts to say .9 volts. This is because the unburnt fuel in each exhaust slug varies a little from the next. It is normal.
But the post-cat O2's should be much steadier and fluxuate slower and less wildly, from say .01 to say .7 Why? Because if the cat is working, it will reduce the oxegen in the exhaust stream as it breaks downs down the hydrocarbons and the result is a much less excited O2.
Now an O2 "simulator" could be used to get the car through emissions. These are illegal devices used by people who have modified their vehicles beyond what the law allows, usually to gain performance. My friend will not consider this as an option. ;~) Nor did he want to spring for the bolt-in factory-fit side flow cat pipe assembly from Walker for around $400.
On a whim, he started using FP in the car. Within a week of 80 miles a day highway driving the code was gone!
So he stopped using FP because that just can't be right. About 2 weeks and 2 gas tanks later, the code was back.
Again he used FP and again a week later the code was gone.
So he quit using FP because this is just a freakish coincidence, right? Well guess what? About 3 weeks and 3 tanks later the code returned.
Now what? More FP and wa-la! Within a week the code is gone. For 3 weeks as of this writing he has been on FP with no cat code!!!
My advice? Do this emissions test that he is required to do in August NOW!!! Now while it will pass!
Many questions remain.
Why is the 30k-40k mile cat going bad? Coolant poisoning? Carbon buildup? Poor design? Bad luck?
What exactly is FP doing to correct the problem with the cat if anything?
But the empirical evidence in this case is, not only will FP probably NOT harm a cat, but it may indeed revive a marginal one or one that that is dead or dying. Or the case could be that FP has cleaned up the emissions enough that that the marginal/dead/dying cat is no longer needed to perform at it its usual level of emissions reduction.
I strongly suspect that FP should extend the service life of a normal cat if used regularly based on this one odd example.
Here are two related threads that came up when I searched this site for similar discussions. Did I miss anything?
http://theoildrop.server101.com/ubb/ultimatebb.php?ubb=get_topic;f=5;t=002999#000000
http://theoildrop.server101.com/ubb/ultimatebb.php?ubb=get_topic;f=5;t=002238#000003
Any comments?
Thanks,
Mike
