No cat...running rich + Missfire

[Backinajiffy12]

Ok so I was running lean due to my cat being clogged, so I took it out! Sounded great ran fine idled a tad high but that was ok. I tuned the other day and it ran OK then today after work it was running way rich and misfiring and sputtering all over the place. What do I have to do to fix the problem?

 

[94Jettameowpsst]

is your second o2 sensor still hooked up?

 

[Backinajiffy12]

yup i figured that might be the problem for the running rich not the sputtering and the missfire. so disconnect it or and a spacer from STM?

 

[Backinajiffy12]

So disconnect or space out?

 

[RedTurboEclipse]

wasnt the 2nd o2 sensor just to read that your car is working. last time i had problems running too rich was when my front o2 sensor was going out.

 

[Backinajiffy12]

So would putting this on help fix my problem? cause i put the stock ECU back in and the problem is gone.
STMDSM - Check Engine Fix- Rear o2 Sensor

 

[97GSTAUTO]

You put the stock ecu in and the problem went away? Weird. I dont run a cat either. I just made myself a 02 sensor simulator (actually 2 because I only run the wideband) to keep the dumb dumb light from triggering.

 

[Backinajiffy12]

Yeah it is way weird that the problem went away. do you think i should just build a o2 bybass

 

[97GSTAUTO]

You might as well. Because you wont pass emissions if you have a check engine light. Hopefully you are in a state that doesnt do the tail pipe test.

 

[ClevelandDSM]

You might as well. Because you wont pass emissions if you have a check engine light. Hopefully you are in a state that doesnt do the tail pipe test.

With no Cat on the car, it has a 0% chance of passing Echeck.

 

[Backinajiffy12]

I Live in Minnesota we dont have smog natzies! But could I use that spacer from STM instead of an o2 bybass?

 

[97GSTAUTO]

With no Cat on the car, it has a 0% chance of passing Echeck.

I do.

In georgia all they do is check your obdII. No check engine light. No problems.

 

[97GSTAUTO]

I Live in Minnesota we dont have smog natzies! But could I use that spacer from STM instead of an o2 bybass?

I would think so. I would search to see if anyone has had success with the spacer.

 

[turboglenn]

I would like to explain something no one else has bothered to notice or mention.

A clogged cat will make you run richer, not having one will make you leaner.

That's a simple fact... now your narrow band 02 might read weird for some reason and make you think the opposite, but with an open cat the more air gets out and more air can get into the motor, thus making it require more fuel or run lean.. a clogged cat does jsut the opposite...air can't get out so less air can get in, and you run rich.

 

[synthetek]

The rear o2 dose not affect how the car runs if your not getting a CEL don't worry about it. A simulator or spacer will eliminate the CEL if you do have one but it will not affect engine performance.

 

[Backinajiffy12]

Ok well if there is no affect on preformance. why is it doing it now when it wasnt doing it befor?

 

[synthetek]

Ok well if there is no affect on preformance. why is it doing it now when it wasnt doing it befor?

The rear o2 sensor has no effect on performance. Your problem is being caused by something else possibly removing your cat or your tuning. Since you have dsmlink you dont need a spacer or anything in the DTC menu you can diable the rear o2 CEL. I dont have a rear o2 at all and use the input from it to log my wideband in dsmlink.

 

[spyderturbo007]

Thank you synthetek, I was hoping someone would mention that the rear O2 has absolutely nothing to do with the way the car runs.