[Czechmate]

Swapped out my stock downpipes earlier today for some AR designs. Jeez that was a rough install. I have never had so much trouble with v clamp bolts or o2 sensors in my life!

Got it done at Pit Row in Santa Clara and I recommend them if you need a fully equipped place to do your own work for a good price.

Anyways, I've put 80 miles on them already and haven't gotten a CEL. All stock car otherwise. Does anyone have some thoughts?

[BSM n54iS]

... Uhh cool story

[msjt]

It'll pop up eventually.

[STR8-6IX]

Originally Posted by Czechmate

Swapped out my stock downpipes earlier today for some AR designs. Jeez that was a rough install. I have never had so much trouble with v clamp bolts or o2 sensors in my life!

Got it done at Pit Row in Santa Clara and I recommend them if you need a fully equipped place to do your own work for a good price.

Anyways, I've put 80 miles on them already and haven't gotten a CEL. All stock car otherwise. Does anyone have some thoughts?

get it tuned... the CEL will pop up sooner or later but thats not that point. your fuel air mixture is all over the place and your ECU has never been more confused trying to figure things out, but it wont... downpipes are too big of a change for the ecu to sort out on its own. get a tune!

[NoQuarter]

Originally Posted by 6IX-F10-N52

get it tuned... the CEL will pop up sooner or later but thats not that point. your fuel air mixture is all over the place and your ECU has never been more confused trying to figure things out, but it wont... downpipes are too big of a change for the ecu to sort out on its own. get a tune!

There will be a CEL light yes. The rest of this I'm not so sure about.

[STR8-6IX]

Originally Posted by NoQuarter

There will be a CEL light yes. The rest of this I'm not so sure about.

you need a tune.. the car will not be running optimally without one.. most of the power is gains from tuning your ecu to run with a downpipe. by itself you dont get full potential of the upgrade.

this has been talked about countless times all over this forum.

[Czechmate]

Getting a tune is a no brainer, I just was wondering why I didn't get a CEL sooner than I eventually did. It took about 120 miles for it to pop up. I guess I don't fully understand how the cpu adapts. I thought it would immediately recognize the difference in particles present

[autoart]

Did you go catless?

[NoQuarter]

Originally Posted by 6IX-F10-N52

you need a tune.. the car will not be running optimally without one.. most of the power is gains from tuning your ecu to run with a downpipe. by itself you dont get full potential of the upgrade.

this has been talked about countless times all over this forum.

You were not talking about not taking advantage of the new potential. Of course you will not get more power without a new tune.

You are trying to make it sound like because someone puts a new pipe on the exhaust the ECU is going to explode.

[shadow191]

Pretty sure that A/F ratios are not going to be all over the place. The O2 sensors can handle it. Downpipes aren't that big of a change. Gains will be much less, but it's not going to damage anything and you could run indefinitely without tuning. I've checked Map 0 when I have to go through the drive cycle for emissions and the A/F is pretty close to when I run other maps.

CEL pops up since the O2 sensors read the same on both which makes the DME think the cats have failed. That doesn't damage anything though. The DME is smarter than you think.

Originally Posted by 6IX-F10-N52

get it tuned... the CEL will pop up sooner or later but thats not that point. your fuel air mixture is all over the place and your ECU has never been more confused trying to figure things out, but it wont... downpipes are too big of a change for the ecu to sort out on its own. get a tune!

[shadow191]

It takes a certain amount of time for the DME to recognize the change. It depends on type of driving - different readiness monitors are set during different speeds. I think the cats set during steady driving from 40-60mph based on the drive cycle instructions. When I have to deal with emissions, it usually takes longest for me to get the cat monitor ready because I live in the city and it's all stop and go.

Originally Posted by Czechmate

Getting a tune is a no brainer, I just was wondering why I didn't get a CEL sooner than I eventually did. It took about 120 miles for it to pop up. I guess I don't fully understand how the cpu adapts. I thought it would immediately recognize the difference in particles present

[Czechmate]

Originally Posted by autoart

Did you go catless?

Yep. Catless AR design

[Czechmate]

Originally Posted by shadow191

It takes a certain amount of time for the DME to recognize the change. It depends on type of driving - different readiness monitors are set during different speeds. I think the cats set during steady driving from 40-60mph based on the drive cycle instructions. When I have to deal with emissions, it usually takes longest for me to get the cat monitor ready because I live in the city and it's all stop and go.

That makes sense. Thanks for that explaination. So the downpipe fixes out there, or even the tunes (jb4, cobb, ect) just constantly clear the fail code? Or do they reconfigure the level of acceptable unfiltered exhaust at the o2 sensors?

[STR8-6IX]

Originally Posted by NoQuarter

You were not talking about not taking advantage of the new potential. Of course you will not get more power without a new tune.

You are trying to make it sound like because someone puts a new pipe on the exhaust the ECU is going to explode.

Originally Posted by shadow191

Pretty sure that A/F ratios are not going to be all over the place. The O2 sensors can handle it. Downpipes aren't that big of a change. Gains will be much less, but it's not going to damage anything and you could run indefinitely without tuning. I've checked Map 0 when I have to go through the drive cycle for emissions and the A/F is pretty close to when I run other maps.

CEL pops up since the O2 sensors read the same on both which makes the DME think the cats have failed. That doesn't damage anything though. The DME is smarter than you think.

the ECU is definitely smart but someone said that their car was running very rich before getting a tune and that it smelled like shit. you car still wont be running very well until you get a tune. a downpipe IS a fairly big change. its not like upgrading your catback where the ECU will sort everything out and make the engine run perfectly fine within a few hundred miles.

bottom line, if you're going to invest into a downpipe, either you do it right with a tune, or you dont do it at all.

[shadow191]

JB4 autoclears the code. The flash tunes like Cobb or MHD suppress it I believe (not too familiar with them). The DP Fix is different in that you wire it inline and it modifies the voltages between the front and rear O2 sensors to trick the DME into thinking your cat is still there.

Normally the O2 sensors read differently front to rear since one reads precat and one reads post. When you take the cats out, they read the same and the DME thinks your cats have failed. DPFix is just a resistor that changes the voltage of the rear one to trick the DME. But it's really only for passing emissions. You have 2 exhaust banks but the DPFix doesn't take that into account so it can cause your AFRs to skew heavily between banks long term if you leave it in.

Originally Posted by Czechmate

That makes sense. Thanks for that explaination. So the downpipe fixes out there, or even the tunes (jb4, cobb, ect) just constantly clear the fail code? Or do they reconfigure the level of acceptable unfiltered exhaust at the o2 sensors?