[zinc76]

I have a "01" Mustang GT and I have a question regarding mid pipes. I notice that the stock "H" pipe has four catalytic converters, if I installed a 2 1/2 inch X pipe with welded in magnaflow catalytics on each side would I still have to use MIL eliminators ?Since Im going from four "cats" to only two "cats"? I was told that you only use MIL eliminators when you're running no "cats" at all. Any input would be greatly appreciated.

[Vision.Pro]

Well actually there are 6 catalytic converters on a stock GT. Just the other day i swapped out the stock H for an o/r H pipe and did not need MIL eliminators. I'm guessing it depends on the brand and where they place the rear o2 sensors. MAC makes them closer to the manifold which helps prevent from throwing a check engine light. Since you are going to stick with cats you should be fine, but every car and brand can be different.

[347stroker]

You will need mil's or you will get a cel. They are not needed at all though it will not hurt your car, will only have the light.

[Vision.Pro]

Originally Posted by 347stroker You will need mil's or you will get a cel. They are not needed at all though it will not hurt your car, will only have the light.

I'm wondering why my car didn't throw a cel when i installed my o/r h then.

[347stroker]

How long has it been installed?

[zinc76]

Regarding 347STROKER, so your saying that even if get a pair of quality catalytic converters welded in on each side of my o/r UPR 'X' pipe that I will probably still get a check in engine light. I guess it depends on the quality of the 'cats' because I've been getting alot of feed back saying that I won't need the MILs if I get 'cats' welded in.

[347stroker]

There are 4 O2 sensors in a midpipe I believe. Therefore if you only have 2 cats yes the other two will throw codes. Thats the point of having sensors.

[Reloaded]

I had a Bassani catted x-pipe and every couple of months it'd throw the CEL. But I work for Ford so I just had it cleared out. But it was usually a month between times it would trip the light.

[zinc76]

So what about when running an off-road X or H, your four sensors are still connected. The MILs are connected to the rear sensors to fool the computer like if they are there to not throw a code, what about the front two sensors that are closer to the manifolds. MILs are not needed there when you run an off road X or H. I think the front two sensor measure the air/fuel ratio.

[Reloaded]

Originally Posted by zinc76 So what about when running an off-road X or H, your four sensors are still connected. The MILs are connected to the rear sensors to fool the computer like if they are there to not throw a code, what about the front two sensors that are closer to the manifolds. MILs are not needed there when you run an off road X or H. I think the front two sensor measure the air/fuel ratio.

Correct. The front two sensors work fine because as far as the computer is concerned, nothing has changed since the o2s are in front of the cats anyway. And if you were to eliminate them, then the car wouldn't run right.

[zinc76]

347Stroker, your four sensor theory does'nt make any since because the front two sensor measure the A/F ratio and there in front of the catalytic on a stock "H" and make no difference on off road pipes. So the sensors that will throw a code if there no catalytic in front of them is the rear sensor. Sorry to correct you.

[347stroker]

If Im wrong Im wrong but I think youll get a cel.

[SMSPerformance]

I have an O/R X and I'm not throwing any lights at all. I must be lucky

[347stroker]

My o/r h threw a code till I shut them off with a tuner.

[SMSPerformance]

Originally Posted by 347stroker My o/r h threw a code till I shut them off with a tuner.

Like I said I must be lucky, the only time I got a CEL was this past sunday when I got a dead porcupine stuck under my car on the X pipe. It shorted out and blew the fuse. Replaced the fuse and everything has been fine a dandy

[347stroker]

Lol nice

[SMSPerformance]

Originally Posted by 347stroker Lol nice

You should see my dog trying to get under my car. I was going to go lower but now I think I'll stay where I am

[03Gtmustang]

i am runing the pypes catted x pipe for 3 months now no cel no mils along as you cats u are fine.

[BLK2KGT]

I just installed my o/r prochamber last wensday and I made my own mil's everything works fine, no codes or anything, and I might add that it sounds awsome.

[zinc02GT]

Originally Posted by Vision.Pro Well actually there are 6 catalytic converters on a stock GT. Just the other day i swapped out the stock H for an o/r H pipe and did not need MIL eliminators. I'm guessing it depends on the brand and where they place the rear o2 sensors. MAC makes them closer to the manifold which helps prevent from throwing a check engine light. Since you are going to stick with cats you should be fine, but every car and brand can be different.

Uhhh, no. Its four. I can go and take a pic of my stock one if you need it...

Originally Posted by 347stroker There are 4 O2 sensors in a midpipe I believe. Therefore if you only have 2 cats yes the other two will throw codes. Thats the point of having sensors.

Originally Posted by zinc76 So what about when running an off-road X or H, your four sensors are still connected. The MILs are connected to the rear sensors to fool the computer like if they are there to not throw a code, what about the front two sensors that are closer to the manifolds. MILs are not needed there when you run an off road X or H. I think the front two sensor measure the air/fuel ratio.

MILs are only needed one the rear O2s that are connected to the crossmember of the tailpeice of the transmission...

If you get a 2 cat midpipe youre gonna need a tune or MILs more than likely because your going from 4 regular cats to 2 high flow cats.