x pipe w/o mil eliminators

I put an o/r x on my 96 GT about 2 months ago. I used the MIL elims and I still got a CEL. My car is running terrible now. I had a friend use his X3 to turn off the CEL temporarily and the car ran fine. He said the code that was being thrown is one that the O2 sensors are not heating up properly. Also the car is running lean one day and back to rich the next. The idle surges when I come to a stop between 500 and 1000 RPM's. I am trying to figure out if I need to replace the front O2 sensors or if I just need to get the car tuned to turn them off. Any suggestions??

Rife96GTconv said:

I put an o/r x on my 96 GT about 2 months ago. I used the MIL elims and I still got a CEL. My car is running terrible now. I had a friend use his X3 to turn off the CEL temporarily and the car ran fine. He said the code that was being thrown is one that the O2 sensors are not heating up properly. Also the car is running lean one day and back to rich the next. The idle surges when I come to a stop between 500 and 1000 RPM's. I am trying to figure out if I need to replace the front O2 sensors or if I just need to get the car tuned to turn them off. Any suggestions??

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Lets add to this post a bit.. I too recently installed a O/R X pipe and only once have I seen a CEL. It poped on one day driving to work and stayed on maybe 3 days and has never come back on. The problem I DO have though that I did not have before is the car will blow some smoke if it's allowed to idle for longer than 10 sec without driving. It never did that before the O/R X and common sense would tell me that the valve seals are going BUT the smoke thing comes and goes. Some days it does it some not, but it's annoying. Does not seem like the cats would contain such emmisions but who knows, my 5.0 never did that so i not starting to wonder if it is indeed a computer A/F issue from the rear O2's not reading right. Just a thought because I am planning to pull the heads for a PI swap soon anyway. I dont have a programmer "yet", anyone live in Jax, Fla that can turn off the rear O2's for me?

1987stangman said:

Lets add to this post a bit.. I too recently installed a O/R X pipe and only once have I seen a CEL. It poped on one day driving to work and stayed on maybe 3 days and has never come back on. The problem I DO have though that I did not have before is the car will blow some smoke if it's allowed to idle for longer than 10 sec without driving. It never did that before the O/R X and common sense would tell me that the valve seals are going BUT the smoke thing comes and goes. Some days it does it some not, but it's annoying. Does not seem like the cats would contain such emmisions but who knows, my 5.0 never did that so i not starting to wonder if it is indeed a computer A/F issue from the rear O2's not reading right. Just a thought because I am planning to pull the heads for a PI swap soon anyway. I dont have a programmer "yet", anyone live in Jax, Fla that can turn off the rear O2's for me?

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How bad is the smoke? I have to imagine that if the cats can oxidize fuel they can oxidize oil and cover up the smoking issue if it is not too bad. As stated above- the only reason the rear O2 sensors exist is to throw the light when the cats stop working.

tonytaylor85 said:

How bad is the smoke? I have to imagine that if the cats can oxidize fuel they can oxidize oil and cover up the smoking issue if it is not too bad. As stated above- the only reason the rear O2 sensors exist is to throw the light when the cats stop working.

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Smoke is not bad, just a puff from both tail pipes when gas is applied at a light or the driveway. I noticed the smoke right after I finished the X-pipe install and as you stated in the previous post assumed that the cats were hiding it too, it's just annoying. I have even been driving my Fox more recently now because of it and I am at a cross roads with it because I have some new combo plans for the Fox so I will prolly scrap the PI swap for now and just do a valve job on the non-pi heads, car has 170k anyway.

BTW: I'm a wizz with EEC-IV in the Fox's, is the ecm in the 96' GT's the EEC-V units? I have been looking at some tuners and I noticed that some tuners (IE: SCT) only list 98-04 models and the Diablo is 96-04 so I figured there was a ECM change at some point during the 96'-98' Model year? This car has just been a no frills DD for me up to this point but you know how Mustangs are you can never just leave well enough alone.

I think the EEC would have changed from IV with the 5.0 to the V with the 4.6 but I don't really know. OBD-II also came that year. Much information on the later half of this page:
Ford Fuel Injection EEC Computers

tonytaylor85 said:

I think the EEC would have changed from IV with the 5.0 to the V with the 4.6 but I don't really know. OBD-II also came that year. Much information on the later half of this page:
Ford Fuel Injection EEC Computers

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Ah, I forgot about that site. Great info there, I used it for my 5.0 Ranger swap some years ago. It answered my question for now. Thanks.