No cats, no MIL's, no CEL?

[ArtSvt]

Im in the middle of doing my 3.0 swap and find out that the previous owner had gutted the pre-cats plus it had no main cat. I also havent seen any sign of MILs used, And Ive never had the CEL lit (other than startup)

Wondering if it could have been tuned to not throw a CEL?

[BrApple]

do you know if the car was ever tuned? if so the down stream sensors, which would trigger a cel if the cats are gutted could have been turned off thus not turning the cel on

[ArtSvt]

Im thinking it was tuned, because he had a nitrous set-up on it before I had it..

Now im worried about what else might have been changed in the programming!

Im planning on getting a tune after the swap, Is there anyway to put it back to stock before hand? Although i kinda like the thurning off the O2s thing

[BrApple]

not sure, I think it depends on how it was tuned. if an Xcal2 was used the Xcal2 has the factory tune stored in it. otherwise I think you could get a new tune by just flashing it again with a Xcal2 , that is unless it has a chip

[warmonger]

It could just be that your system hasn't hit the catalyst monitoring test yet in your drive cycles. The cel won't come on right away with just gutted cats. As long as everything else works then they will only come on when the conditions are met for the PCM to execute the catalyst monitoring test.
Or it could have a tune in it with the lower O2s turned off.

[svtpimp]

I installed my msds headers and y-pipe over a year ago, and about 6 months ago I smelt burning. Turns out my rear o2 MIL melted all together. Removed both of the MIL's and been driving for 6 months no cel.

[Augi]

I installed my msds headers and y-pipe over a year ago, and about 6 months ago I smelt burning. Turns out my rear o2 MIL melted all together. Removed both of the MIL's and been driving for 6 months no cel.

I have a zetec with a gutted cat and at first Ithrew a light for it, then it just up and stopped throwing codes but every other week for a couple of days. The code it thows though is saying that the MAF is malfunctioning, not the CAT.