Relationship between having no cat and check engine light
 

On my turbo project there is a resonator pipe instead of a cat for more flow. My car is throwing check engine light on and the code says it's the O2 sensor after the cat, meaning the cat needs to be replaced. After this happens it seems to run crappy and I can't get alot of power out of it. When the check engine light comes on does it put the computer into some kind of safe mode? Would this have an effect on performance? Is there anyway to trick the computer so this doesn't happen. has this happened to anyone else? Any input would be appreciated. Thanks

Re:Relationship between having no cat and check engine light
 

I had the same problem with my car, same as yours but a 97, it did seemed to run better and it was the second sensor, I have no cat, straight pipe, and no turbo yet, but yes the ECU will run in kinda Safe Mode to protect the motor. I just swapped my ECU for an OBD1 ECU from a 95 EX. I got the ECU free but had to pay like $170 for the convertion cables, Skun2 ones sell for like $265, so it was a pretty good deal, and it has been running perfect for about 2 weeks now no check engine light. Before I would reset ECU and light will come back up in 2 days.
David

Re:Relationship between having no cat and check engine light
 

I have a 95 ex with a straight pipe and no engine light comes on, not even with boost. Checked engine light and it does work it just doesn't recognize boost.

Re:Relationship between having no cat and check engine light
 

Interesting.. are you getting a catalyst effiency type code? or just an o2 code?

I didnt know those codes would put the computer in a "limp in" type of deal. Some Codes will change how the car runs. For OBD2 setups I have seen people getting o2 simulators after they take the cat out..

http://userwww.sfsu.edu/~ecg/o2sim.htm

Jeff

Re:Relationship between having no cat and check engine light
 

It's showing a catalyst effiency code. I think I'm going to try getting the o2 simulator. Thanks

Re:Relationship between having no cat and check engine light
 

;D ;D
Yea same thing happened to me.
Ive got a'99 y7 . I thought only the primary o2
sensor mattered so i put it in the std man.
and the secondary o2 in the downpipe of
my turbo . no dice. OBD2.5 or whatever you
want to call them ('99 & '00) do go into a limp
mode.I had to put a flowthrough smog legal
cat for a y8 with an o2 bung welded on it
on the end of my midpipe. no CEL.


let me know how the o2 sim works cost
and where you got it. be cause i also had more power before i had to istall cat

Re:Relationship between having no cat and check engine light
 

You can get it at Summit

Re:Relationship between having no cat and check engine light
 

for cars 96-00 if u take out the cat and use a test pipe u have to have a o2simulator to have NO CEL. heres the o2 simulator http://userwww.sfsu.edu/~ecg/index.htm it will put u in limp mode if u have no o2 simulator

Re:Relationship between having no cat and check engine light
 

Didnt I just say the exact same thing? I post the same link? ::)