Contour Enthusiasts Group Archives Forums Modifications Duratec Performance mystery mod

i read some threads that i got from the search feature and since my car has OBD-I, then would it be possible to just put in a OBD-II then do this mystery mod? My reasoning is that since the OBD-II is more adaptable to changes then would this bring more results(or should i say better results) than the the OBD-I? TIA

i did it on my obd.1 and it worked out just fine thanx

Sorry I am kinda new to this but what the
#$%* is OBD. I have know idea what that is and also what is the mystery mod.

XTREMECONTOUR - couldn't tell you what OBD-I and OBD-II stand for...
I probably shouldn't even murder their definitions but - they're essentially the computer systems in our cars (all fords?), and OBD-II replaced the elder OBD-I a few years back (96?). Mystery mod is :accidentally: removing the material from your light off cats.
red95SE - Find Bicycle019 and see what he says. I know he's mystery modded w/ OBD-I and he got results. I'm not too sure how easy the swap from I to II would be, or if it would even be necessary.
HTH

thanks derk will contact him.

the only thing i am worried about when doing this is getting someone to weld the hole i drill in them to remove the "unnecesary guts". but other than that i know that i have to move the alternator brace to help with access issues for the rear. i have heard the front one comes off easily. when i was changing the oil the other day i sprayed all the nuts/bolts with penetration liquid to help when i do this. this is a must when removing rusted bolts that you wish to reuse. :p

OBD= On Board Diagnostics, All vehicles are mandated by the feds to have this. OBDI has been around since the 80's and OBDII has been around since 96' and it will monitor your engine with greater detail than before. AS a matter of fact Our 02" Explorer has a light on the dash that tells you to tighten your gas cap!

OBD I is only on the 95 cars. 96+ use the OBD II system, like jetace mentioned. The reason this comes into play when making the mystery mod is that the OBD I cars have 2 oxygen sensors in the exhaust system, both of them being upstream of the pre-cats. The OBD II cars have 4 O2 sensors, the two upstream ones, and two sensors downstream of the pre-cats. Once you umm.. mod the cats, the second set of O2 sensors know something is up, and trip the check engine light (CEL). 95's don't have the second set of O2 sensors, so no CEL light gets tripped when you mod the cats.
Newer cars (96+)can get around the CEL by installing MIL eliminators, which are basicly resistors that change the signal that the second set of O2 sensors send from a bad one to a good one. There has been lots of info on the "Mystery Mod" and "MIL Eliminators".
I noticed a good gain by doing the mystery mod. Total cost was cheap (under $50 total) but labor was on the longer side. I'd call it a 10 hour job from pulling the manifolds, "modding" them, and then re-installing. If you can find an extra set of manifolds to mod from someone who has done a header install, I'd get those and mod them at your leisure, then just do the install when you have time. That's what I did. Good luck, and If you have questions, the Search function works well, but you'll have to look thru alot of post on this topic to distill the info needed.

If you're going to play with your motor/emissions you're best off with OBD1 anyways. You'll have an electrician's worst nightmare trying to convert EEC4 to EEC5.

10 hours to do the precats... OUCH.... with proper tools i can do them in 2 hours... you don't need to remove the rear bank to do them... just take the y-pipe off and use a big screwdriver... the front ones i found that the handle on a 5 gallon bucket, then straightent he handle out a bit but leave the hook part on the end, and cut it so that you have about 12-18"... now insert into drill, insert hook end into 1/4" hole in front bank manifold and turn drill on... i was able to gut a front set of pre-cats like this in about 20-25 mins.... also used a hammer to bang on the manifold every couple of mins.... oh yeah and a dremmel to port that lip on the front manifold helps out too.... we did an ATX last weekend and the owner felt very good gains and is very very pleased.

also note, 2001+ vehicles only have one downstream sensor which is aft of the main cat so you don't need MIL Eliminators on those's either.

The front manifold has lots of crap around the ports which impede flow quite a bit. Grinding down this crap and smoothing it out was at least 2 hours itself. You don't need to do it, but every bit helps! Also, besides the cat material, there is a cotton type wadding material and TWO steel wool bands in those pre-cats as well. I really wanted to make sure the front manifold was clean, and removing it is the only way to do that IMHO.
The rear CAN be done on the car, but you risk getting cat material in the open exhaust ports if you get too vigerous with the screwdriver banging away at the cat. Practice makes perfect Puck, and I bet I could do the job in half the time the second time, but for the novice to Duratec manifolds, it's a long job with lot's of extentions and tight confines. In the end though, it was worth it..

Alex