Help with SERVICE ENGINE SOON light
 

I have a 2002 Mustang coupe, had my cats cut off and instaled two flowmasters. After one month the "service engine soon" light came on. When they cut the catalitic converters, they left the emisson sensors in place (they are located right before where the cats were). The car runs great, found no problem so far. I checked the owner's manual and it says it could be:
- Problem with emission control system, or
- bad quality fuel (which is not), or,
- Fuel cap is open (not my case),
How can I check the emission control system? Does anyone know what sensors and what parts I need to check? THe car is almost brand new, so I guess there shouldn't be any defective parts.
How can I shut down this damn light??

You're probably going to have to pull the engine codes. If you have an Auto Zone in your area, they will do it for free.

There's one not too far. Thanks for the tip !!!

Is it possible to pull out these codes by myself?

Your problem is the O2 sensors have to have the cats there in order to read your exhaust correctly. Without the cats on a modular motor car such as your 4.6L you will have to buy what are called MIL eliminators. These plug inline with your O2 sensors and keep the Check engine light from coming on (basically tricks the computer). When that CEL comes on it triggers the computer into somewhat of a "safe" mode (like pulling some timing out) so you will lose power with that light on. Some places like Dallas Mustang sell the MIL eliminators and they are very easy to install. Go to the Modular Madness forum on this board and do a search for the MIL eliminator and you'll find all you need to know including where to get them.

one more doubt
 

I still need to pull out the codes before buying these mil eliminators. According to http://www.mileliminators.com their mil elim. only prevent the low cat efficiency codes P0420 and P0430.
I have one more doubt that you guys may be able to help me:
The original X pipe was removed and two straight pipes were installed. There is no connection between the exhaust pipes. It is not a H pipe. It is like two I's instead. Does anyone know if this can be any worse or better than having a H pipe or the original X pipe? The mechanics who made the "conversion" (since it had only one exhaust pipe before - it's a V6 coupe), said that there woudn't be any problems in removing the cats and putting two strait pipes with flowmasters on each one of them. They even said that I would have more horse power by doing this. Is this true?

You WILL need the MIL eliminators. You don't need to pull the codes unless you really want to. Just install the MIL's and disconnect the battery a while to reset the computer to erase the codes. If the CEL comes back on later then pull the codes and see what it is because it'll be some thing else than the O2 sensors. You DO need the MIL's though when you get rid of your cats. The reason is the way these new OBDII computers are programed for emissions.

You DO need the H-crossover. Those guys are full of crap! Take some black spray paint, or even a crayon and make a line from front to back down the mid-pipes. Where the exhaust heat burns it off of the pipe is where the crossover pipe should be placed. There will be a spot on each pipe where it'll burn out a spot of the paint or crayon. It's all about the exhaust pulse going down the pipes. The crossover pipe equalizes the pressure between the two pipes. If not, can we say Back Pressure?? You definitely need the H-pipe crossover tube.

I've already bought the MIL eliminators. (paid $30 for the pair) I will install them pretty soon and I'll let you know if they work OK.
About the H-pipe crossover tube, I thought about it and you are probably right. I don't know who soon I will be able to install this crossover pipe, but hopefully this is not doing any damage to the engine.

Thanks for all your help.

Not having the crossover tube right now is not doing any damage to your car. It's just got less power than it would have if it had the crossover tube. Good luck.