Downpipe without tune?

[twolf]

I'm about to make a 2 hour drive, 2 ways, with my new downpipe installed. I haven't contacted my tuner yet...

Should be fine right? I'll just get a CEL halfway through probably.

Should I avoid going WOT?

 

[commonplatypus]

You will get a CEL for Catalyst Efficiency Threshold, but not much else. You're only running it a short amount of time. I would avoid WOT until you get tuned and monitor AFR to ensure you do not run lean. I assume you'll be putting a defouler on the downstream 02 sensor, as well? Might get some soot buildup on the 02 sensor, but you're only doing a two hour trip, so you'll be fine I think.

Is this a catless downpipe or catted?

 

[twolf]

Catless. No defouler.

 

[commonplatypus]

Is there a reason you're running without a defouler?

 

[twolf]

Not really. Why would I run one if I can turn the sensor off with a tune?

 

[StayPuft]

I'm running catless dp with Cobb ots s3 tune. cel for downstream o2 obviously but no other issues.

 

[frankiefiesta]

Not really. Why would I run one if I can turn the sensor off with a tune?

I may be wrong, but I believe it is still used for tuning purposes

 

[Wcyracer]

What about the same question but catted?

 

[StayPuft]

I believe the downstream or post cat o2 is used for emissions and to measure whether the cat is heated not for tuning/hp purposes. My DHM catless dp didn't even come with a downstream o2 bung.

What about the same question but catted?

Should work like stock. Some people opt to use an "o2 simulator" or "defouler" to trick the computer into believing there's a rear o2 that's doing it's job. Really no difference in not running one at all other than a light on the dash until you get as protune.

 

[MOFiST]

What about the same question but catted?

I sometimes run my 2jr catted dp with the OEM tune for factory servicing. I left the OEM tune on for over a week and saw no CEL.

 

[haste]

I'm currently running full cp-e turboback. i will revert to stock tune at some point and test out their defouler. it came with 3 fittings for flow to the sensor and i installed the smallest. i will update when i test it.

 

[twolf]

Yeah that was a 200 mile drive and my CEL never popped on. Weird.

 

[PhoenixM3]

I sometimes run my 2jr catted dp with the OEM tune for factory servicing. I left the OEM tune on for over a week and saw no CEL.

Why would you get a CEL with a catted dp?

 

[MOFiST]

Why would you get a CEL with a catted dp?

On my previous Mazda I did get a CEL with the high flow cat.
I think that was bad cat placement though and the cat wasn't getting hot enough...
But I thought I remembered Mountune saying a tune was required for their catted pipe and maybe Cobb?
I don't know 100% but I thought I'd share my observations YMMV.

 

[Klink]

I have a stock exhaust with the catless ATP, and my fuel millage dropped like 5mpg. No tune yet, was talking to Randy for one soon, with the tune remove the engine light?

 

[twolf]

Weird, my fuel economy didnt drop. Tune will remove the light.

 

[haste]

I installed pumaspeed manifold and catless downpipe and my mileage also decreased more than I expected. The affect of more accelerator pedal action after said parts were installed could be a huge factor though...

All my emissions equipment is showing ready...CP-E defouler must be working. I am tempted to remove the Cobb Stage 3 OTS tune completely to see if I get a CEL.