Do I need a tune? Odd AFR readings after LTH job.

[Toasteii]

Just installed BBK Catless 1-3/4 LTH's took it on a 20-minute test drive with full open headers. Noticed at idle was hovering around 14.5 AFR, which is okay. Although under light to somewhat medium throttle cruising, I was getting around 17-18. Also had the car die on me at a stop light, coming from 4000 RPM back to idle with the clutch in. I can't install the exhaust yet, as I got a killer deal from my buddy at the dealer, so I need to get it modified to work with the 2-bolt flange-style on the header. Is this a collector not long enough problem, and the O2's don't have enough breathing room to measure accurately, or is this a I need a tune problem, or maybe a whole different problem/car takes a while to learn? The only other engine mod is the K&N CAI that came with the car.

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[Fordphanatic]

Why did you go with catless headers on a STOCK car? You most Definitely Need a tune and your going to have to find a tuner to shut off your CEL.

 

[Toasteii]

Why did you go with catless headers on a STOCK car? You most Definitely Need a tune and your going to have to find a tuner to shut off your CEL.

Will Do! Went with catless for some future plans I have for it, just slowly piecing it together. Not super concerned about the CEL, just seen conflicting information from people on the forums about headers not needing tunes, etc. I also think my AFR numbers are being thrown of just by how close the Wideband is to the end of the collector with nothing else back there so its more than likely pulling some fresh air in.

 

[Pistol_91]

You don't need a tune for headers but it's good to get one to optimize performance and change o2 delay since they sit further back. It probably stalled because you're running open headers...
Once you get your exhaust put on the AFR will get better. Either way the long term fuel trims will take care of the indifference in the meantime. The more you drive it the more the fuel trims will get closer to 1.0 lambda.
Just put the exhaust on, don't be ghetto lol

 

[Toasteii]

You don't need a tune for headers but it's good to get one to optimize performance and change o2 delay since they sit further back. It probably stalled because you're running open headers...
Once you get your exhaust put on the AFR will get better. Either way the long term fuel trims will take care of the indifference in the meantime. The more you drive it the more the fuel trims will get closer to 1.0 lambda.
Just put the exhaust on, don't be ghetto lol

100% Agree with you was definitely fun for the test, just scared me seeing the readings that lean the first time, just wanted to make sure im not hurting the engine, just gotta bring it to the shop so they can modify it for me and all should be good. Probably gonna buy BBK's 3-inch exhaust flow tubes just so the flange part is dealt with and may not even need to bring it to a shop, may get lucky and the rest of the exhaust slips together

 

[2015 Silver GT]

and your going to have to find a tuner to shut off your CEL.

What tuner is going to commit a federal crime by turning off the rear O2’s? The answer is none.

 

[Swtbabybilly]

You dont need a tune and tuners will not just turn off you check engine light, best of luck

 

[Fordphanatic]

What tuner is going to commit a federal crime by turning off the rear O2’s? The answer is none.

That's my point!

 

[engineermike]

….I also think my AFR numbers are being thrown of just by how close the Wideband is to the end of the collector with nothing else back there so its more than likely pulling some fresh air in.

This. I’ve experienced it before.

 

[junits15]

Yeah you can’t run with the wideband that close to an open pipe.
No tune needed.

 

[Toasteii]

Appreciate y'all's help, will get this sorted soon!

 

[NightmareMoon]

yeah a leak (or an open header) near the sensor will cause the 02 sensor to read lean.

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