replacing the Pre-cats or not.... that is the question!

[Monkay619]

I realize that my post is kinda long, so this is what I am looking for/asking:

1)What does the bank 1 pre-cat look like (any suggestions on a relatively inexpensive place to get one?)
2)Since this is my DD, should I fix the problem (replace the pre-cat) or save $$$ and ignore/bypass it (fooling he CEL?)

This is what my problem is:

Got my car back from the mechanic (it is my DD), and my CEL is due to the Bank 1 pre-cat (apparently the one bounded by the firewall). And I need a new intake manifold gasket. All together I’m looking at $1200, of which $1000 is from the pre-cat ($641 parts and $3?? Labor)

Considering that that is a bit more than ¼ what I paid for the car :nononoand I have had it for just over 1000 miles) I wanted to explore my possibilities before I put more money into it (especially if this is a sign of what is to come, maybe not a good idea to put too much money in). BTW, is that normal for the pre-cat to go with just over 75k?

The way that I see it as of right now, I have 3 options (any ones that I missed?):

A)Replace the pre-cat and pray that never happens again.
B)Not do anything, keep the CEL (and the worse MPG right?).
C)Install an o2 Mil /simulator (MPG as B).


Now if money were not an issue (but I just got engaged:help, I would do “A” since it takes care of the problem and emissions (oh, if there is a pre-cat failure, what is it due to? Should I not be fixing that, thus fixing the problem, not just the symptoms?).

I could get away with “B” since I just got the car, and will not need it emission tested for another 2 years. The only “problem” I see with that is I would not know if more CELs would be coming on, since it would be on all the time.

If I were to go through with the “C” option, then I would get decreased MPG, no CEL and pass OBDII when emissions come around. From my preliminary research, they can be made for less that they sell for assembled for $40 (what doesn’t cost less to make) and are relatively simple to install (but I have not grasped that yet, where does it go? The wiring harness I’d assume, right by the O2 sensor?:shrug

Now I have been looking for replacement pre-cats, but have been finding it difficult to nail down what I need because of the diversity in nomenclature. I read here that everyone calls them “pre-cats” however online parts websites do not have that distinction, they seem to all be Catalytic converters. Moreover, they tend to call them “front” when it is by the radiator, and then they have “rear” and ones that are not specified…. So is the rear one the last one? Or the middle one (which I need right?) I think that they refer to it as rear in terms of the 2 pre-cats? All this would be less confusing if I knew with certainty what the part looks like…. Is this the sucker: http://www.discountconverter.com/direct_fit_catalytic_converters/direct_fit_detail.cfm?productID=172:shrug:

Let me also make sure, the pre-cats are the same for all Duratec (ie SVT and non SVT), as long as they are MTX?

Side note about MPG (you will have to follow my rambling a bit more on this one, and I promise it will make sense by the end): I have only had the car for maybe 3-4 tanks? So I do not yet have a solid grasp of my MPG, but I do know that my best was 24 MPG on a trip with mostly highway, and going easy on it (not spirited as I usually drive), which gave me just barely over 300 miles to the tank I think I get closer to 280 on a tank (which equates to 23.3MPG) from what I read on here, that is terrible, and most of you seem to be getting at least 350 miles. Average EPA estimated yearly mileage is what, 15k? I’m in college, so I’m not going to put on that many, maybe 10k? so over 2 years (because I will need emission testing then, and if I do not pass I will need to put replace the cats for real) 20’000 miles, if I get 23.3MPG that is 857 Gal, if I get 28.3 MPG (that is 340 miles per tank, taking 10 off the 350 to be “conservative”) then I would use 705 Gal. If I save those 152 Gal @ $3 I would be saving $456 (aka the cost of the Pre-cat, but not the labor). So my point is that it might be better to just replace pre-cat in the first place.

Any additional information/insight is much appreciated, I hope this was the "right" section to post in


Thanks in advance


~Mike

 

[striker2]

chances are your pre-cats arent actually toast. im assuming the code you got (if you dont know ask the mechanic what it was) was a P0420. more often then not this is a false code. your options are either install MIL eliminators (last resort IMO as its not really a fix), replace the O2s (all 4), live with the CEL, install headers, replace the probably perfectly functioning pre-cat, gut the pre-cats.

when i had the P0420/0430 i replaced all 4 O2 sensors and the codes have not come back in about a year now. the reason this works is because the PCM compaires the downstream sensor switch rate to the upstream sensor switch rate. if the upstream sensor is old and a little lazy, but not enough to trip a code for it, then the PCM may trip the P0420/430 codes for the pre-cats.

if you gut the manifolds or install headers you will have to install MIL eliminators anyways (PS i have a set of gutted manifolds for sale in the classifieds, PM me if your interested). both will give you a slight gain in power, with the headers being about 10-15more HP and the gutted manifolds being about 5HP. as long as the car is warmed up before you go to emmisions you will pass a sniffer test (if they do one) as the main cat does all the work at that point.

if you decide to replace the pre-cats then you need to look for exhaust manifolds as the pre-cats are built into the manifolds.

as for your MPG, thats about what i get and have gotten from day one. there are some people who manage to get in the high 20s to 30 but i have only been able to get that on a strictly all highway tank of gas.

 

[SVT Doood]

O2s

O2s

O2s will run you about ~$200 (for all 4) from www.sparkplugs.com for NGK O2s. An intake manifold gasket set will run you ~$40, but you'll want to replace the TB gasket after you clean the EGR passage behind it (believe me...you will), and the TB as well, and perhaps the IAC gasket. A few cans of B-12 to clean the UIM and LIM, and you're at what...$275 for a car that should run a lot better. Hell..while the UIM is off, throw in a new set of Autolite XPs for another ~$40.

If all that does not cure the CEL, gut the cats and install MIL eliminators.

 

[turbo_fox]

a p0420 will not effect your fuel mileage. It is a cat monitoring system only, and the code is merely telling you that your cat is not doing an adequate job. The only exception to this is if the cat is actually bad, and has started to melt and plug up. This is probably not likely. I would change the upstream and downstream on that side. You can also bring the car to a ford dealer. there is a TSB that gives you a reflash from ford to expand the parameters

 

[Monkay619]

I called the mechanic and asked him if he remembered what the codes were, he said that the intake manifold leak was a P0174 and could not remember what the other one was, when i suggested P0420/0430 he said he thought that it was the P0420 (however since the CEL is still on, so I'm going to stop at an advanced auto or something and find out for certain.).

When i was looking for the technical service bulletin (TBS) I found this, and thought that it might be of use (IDK it probably is already posted somewhere on CEG, but here it is anyways): http://www-odi.nhtsa.dot.gov/cars/problems/tsb/tsbsearch.cfm

So far, changing the O2 sensors sounds like the plan... thanks for the help guys, really appreciated

 

[Big Jim]

I started a reply this morning but ran out of time. I see that much of what I wanted to cover has been covered by others.

You need to be aware that the cat efficiency codes on our cars is often a phantom code. Ford actually published a TSB that applied to some Contour V6 models that widened the parameters for setting those codes.

I have had those codes from about the time my car was three years old until about two years ago. The code would set, I would clear it, and it would not return for anywhere from six months to two years. Sometimes it would be the rear bank (more often) and sometimes it would be the front bank. Scanning the system showed that indeed the upstream and downstream sensors were giving the expected results while scanning them. I still have the original cats. Bought the car new and now have 253,000 miles on it. Every time I have had a smog check, the readings are ultra clean. I truly don't think there is anything wrong with any of my cats.

It would help to understand how the cat monitor works. It is a program in the PCM that checks the efficiency of the cats. It runs periodically, not all the time. It runs after all the other monitors have run, including the one that tells you the fuel cap may be loose. Even after the other monitors have run, it does not run until certain driving conditions have been met. It is something like fully warmed engine, then steady speed above a certain level for a certain time. I had understood that it would not run until it had also idled for a short time (a minute or so, like at a stop light) but the light did come on for me a time or two at steady freeway speed.

What the cat monitor does is check the difference in the reading of the upstream and downstream oxygen sensors. Oxygen sensors generate a mild voltage in the absence of oxygen. Lean (lots of oxygen) reads about .1 volt. Rich (little oxygen) reads about .9 volts. The upstream sensor is constantly and rapidly switching from rich to lean and back due to the pulsations from the opening closing of the exhaust valves. A properly operating cat dampens this action so the downstream sensor switches much more slowly. When the cat monitor runs, if it sees that the downstream sensor too closely mirrors the action of the upstream sensor, it trips the code and sets the light.

There are other things that can effect this balance. Your intake vacuum leak could conceivably do it. A lazy upstream sensor could do it, even if it is not lazy enough to set an upstrean sensor code.

My vote is for fixing the intake leak and then seeing what you have. If it only comes on ocassionally, just reset the light and don't worry about it.

Just for the record, I have not had the problem since I had a rear bank upstream sensor fail and replaced both upstream sensors.

I hope this helps.

 

[Monkay619]

Wow. First of all I would like to thank you all for all the information and explenations :laugh: its very much appreciated!!

Now, Yesterday I was able to get the codes read to me again, and they are as stated above: P0174 and P0420.

I have since researched online more about the TSB and think that it is NHTSA item # 10008993 (which I had some difficulty finding since they listed it against the "Electrical System" as opposed to "Emissions". I made an appointment with a local Ford dealer to get the ECU flashed which will hopefully expand the tolerances and not have this "false positive" again! since there is no warranty existing on the car it will cost $89.95 + tax, which is by far the cheapest option to date.

From what i have read, I'm pretty confident that it will work, if not, I will proceed to have the O2 sensors changed (correct me if I'm wrong, but it sounds like the best option is just to change them all, instead of just doing the first ones aka the ones in front of the pre-cats). Last option would be to change the pre-cat, but that seems quite unlikely at this point (and if it is, then I'm going to look up something i read about a 8 yr/80k federal warranty on vehicle emission components (since I'm almost at 76k).

Thanks again to everyone, I'll let you know what happens when it happens :laugh:

 

[turbo_fox]

Wow. First of all I would like to thank you all for all the information and explenations :laugh: its very much appreciated!!

Now, Yesterday I was able to get the codes read to me again, and they are as stated above: P0174 and P0420.

I have since researched online more about the TSB and think that it is NHTSA item # 10008993 (which I had some difficulty finding since they listed it against the "Electrical System" as opposed to "Emissions". I made an appointment with a local Ford dealer to get the ECU flashed which will hopefully expand the tolerances and not have this "false positive" again! since there is no warranty existing on the car it will cost $89.95 + tax, which is by far the cheapest option to date.

From what i have read, I'm pretty confident that it will work, if not, I will proceed to have the O2 sensors changed (correct me if I'm wrong, but it sounds like the best option is just to change them all, instead of just doing the first ones aka the ones in front of the pre-cats). Last option would be to change the pre-cat, but that seems quite unlikely at this point (and if it is, then I'm going to look up something i read about a 8 yr/80k federal warranty on vehicle emission components (since I'm almost at 76k).

Thanks again to everyone, I'll let you know what happens when it happens :laugh:

if you have a 99 then you are out of the federal warranty.

 

[Big Jim]

Wow. First of all I would like to thank you all for all the information and explenations :laugh: its very much appreciated!!

Now, Yesterday I was able to get the codes read to me again, and they are as stated above: P0174 and P0420.

I have since researched online more about the TSB and think that it is NHTSA item # 10008993 (which I had some difficulty finding since they listed it against the "Electrical System" as opposed to "Emissions". I made an appointment with a local Ford dealer to get the ECU flashed which will hopefully expand the tolerances and not have this "false positive" again! since there is no warranty existing on the car it will cost $89.95 + tax, which is by far the cheapest option to date.

From what i have read, I'm pretty confident that it will work, if not, I will proceed to have the O2 sensors changed (correct me if I'm wrong, but it sounds like the best option is just to change them all, instead of just doing the first ones aka the ones in front of the pre-cats). Last option would be to change the pre-cat, but that seems quite unlikely at this point (and if it is, then I'm going to look up something i read about a 8 yr/80k federal warranty on vehicle emission components (since I'm almost at 76k).

Thanks again to everyone, I'll let you know what happens when it happens :laugh:

DON'T CHANGE THE DOWNSTREAM SENSORS. IF ANYTHING YOU WANT THEM TO BE LAZY.

Also get the vacuum leak fixed as it may be contributing to the problem.

 

[Monkay619]

if you have a 99 then you are out of the federal warranty.

Ok, that is why i was going to look it up, I was suspected that it was whichever comes first kinda deal.

DON'T CHANGE THE DOWNSTREAM SENSORS. IF ANYTHING YOU WANT THEM TO BE LAZY.

Glad i coublechecked then, that makes most sense

Also get the vacuum leak fixed as it may be contributing to the problem.

That will hopefully be done either on Monday or Tuesday, I figured that Flashing the ECU would not interfere with that, so I just scheduled that as soon as possible. (if the dealer can do it for a reasonable price/when i go for the ECU, i'll just have them do it:shrug

 

[Big Jim]

You should be aware that there may not be a new program, or if there is, it may not address the cat code problem. It is probably worth doing anyway.

When I tried to have mine reflashed, there was no revised program available.

 

[Monkay619]

Well, according to the Dealership, I already have the latest revision for the "PCM", and they asked me if i wanted to have them diagnose the problem (since it would have cost me the same amount (well plus time) I didn't see a problem with it.

There diagnosis is that I need BOTH Pre-cats AND intake gaskets!! :nonono:(which I'm guessing is BS... and makes me wonder if they even bothered to do the ECU re-flash as requested):nonono:.

I set up an appointment with the previous mechanic that diagnosed the problem to have the intake gasket done and change the "front" O2 sensors for each bank.

Thanks again for all of your inputs :laugh:

You should be aware that there may not be a new program, or if there is, it may not address the cat code problem. It is probably worth doing anyway.

When I tried to have mine reflashed, there was no revised program available.

just saw your post after i wrote what is above, I'm fine with it not having fixed the problem, after all the TSB is 5 years old, chances are that it was already done, I'm just talking the approach of cheapest fix first, and hoping that i stop sooner rather than later

 

[Dyoel182]

Cheapest fix but you have it at the dealership? In my mind cheap is throwing some anti-foulers on the lower sensors for $5 and seeing what it does.

 

[icysvt]

Seriously I would not pay the amount they will charge to do the intake gaskets. They aren't hard to do and the gaskets aren't expensive either. You most likely have locals near you that would or could help you if you needed it.

 

[Monkay619]

Cheapest fix but you have it at the dealership? In my mind cheap is throwing some anti-foulers on the lower sensors for $5 and seeing what it does.

Point taken, but i am trying to a certain extent to fix the problem, not just the symptoms, and it was cheaper as in $100 for the flash vs $200+ to change all the O2s vs $1000 for the cats

Seriously I would not pay the amount they will charge to do the intake gaskets. They aren't hard to do and the gaskets aren't expensive either. You most likely have locals near you that would or could help you if you needed it.

You are probably right, I should try myself, and i hope that I will start doing so sooner rather than later. Right now I definitely lack any experience, or knowledge (like the fact that it is a relatively simple job). If something falls through with my current plans, I will definitely buck up and try it myself!

 

[Dyoel182]

Point taken, but i am trying to a certain extent to fix the problem, not just the symptoms, and it was cheaper as in $100 for the flash vs $200+ to change all the O2s vs $1000 for the cats

Well automatically those last 2 options would be out for me and I certainly wouldn't be looking for a reason for a dealership visit. Actually I'm not even sure they'd know what I was talking about if I came in and mentioned the PCM. I'd be breaking out the air tank, hose and air leak adapters I made years ago for my mazdas to see if I could make something hiss.

 

[Monkay619]

201 Miles after i got the car out of the shop the CEL came back on (I think we can assume what the code is, but i will go have it read later regardless). besides the intake gasket, the O2 sensors were supposedly checked, and only the bank 2 one was replaced, but "hooking it up to the computer" showed that the reading from the first and second O2 sensors were "identical".

Sounds like I'm going to be looking at MIL eliminators (and headers? while I'm at it?).

This time, I will be trying myself *fingers crossed* :laugh:

 

[turbo_fox]

they didnt change the upstream sensor on bank 1? they should have done both

201 Miles after i got the car out of the shop the CEL came back on (I think we can assume what the code is, but i will go have it read later regardless). besides the intake gasket, the O2 sensors were supposedly checked, and only the bank 2 one was replaced, but "hooking it up to the computer" showed that the reading from the first and second O2 sensors were "identical".

Sounds like I'm going to be looking at MIL eliminators (and headers? while I'm at it?).

This time, I will be trying myself *fingers crossed* :laugh:

 

[Monkay619]

they didnt change the upstream sensor on bank 1? they should have done both

I had origginally asked them for that, but then i got persuaded from the guy on the phone that they were not neccessary, wheni go pick it up, he tells me that he had changed the one (yes, bank 2) and that he "hooked it up the PC" and all that crap.

I might be happy they did not, the O2 sensor that they got from Ford was $117!! I got a Bosh (which i think is OEM right?) from Autozone for $50. I just need to find out how to change it (i remember seeing a writeup, and something about small wrists are a plus... lets hope it works).

Thanks for all your help, I totally should have been doing some of this on my own instead of getting :blackeye:

 

[turbo_fox]

I had the same problem on my 99. I datalogged with the PC and it was the same, upstream o2 matched the downstream. I just swapped the upstream and i have no light anymore. It wasnt too bad, took me about 45 minutes to change.

I had origginally asked them for that, but then i got persuaded from the guy on the phone that they were not neccessary, wheni go pick it up, he tells me that he had changed the one (yes, bank 2) and that he "hooked it up the PC" and all that crap.

I might be happy they did not, the O2 sensor that they got from Ford was $117!! I got a Bosh (which i think is OEM right?) from Autozone for $50. I just need to find out how to change it (i remember seeing a writeup, and something about small wrists are a plus... lets hope it works).

Thanks for all your help, I totally should have been doing some of this on my own instead of getting :blackeye: