Catless exhaust..Tune required?

AshtonC04

Member
Jul 31, 2020
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I’ve just ordered an Off-road X (Catless) From Jegs.com. Will the 02 Sensors adjust the A/F Ratio on the factory Tune? I’m aware i will get a check engine light. Just wondering if going catless on stock tune will cause damage.
 
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Bullitt95

10 Year Member
Jun 13, 2007
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The upstream O2 sensors will continue to read and adjust the A:F ratio as normal but since the downstream O2 sensors will detect that there are no cats, they'll trip the CEL. You can either have the downstream O2 sensors disabled in the tune or install MIL eliminators to trick the ECU.
 

AshtonC04

Member
Jul 31, 2020
10
1
13
17
United States
The upstream O2 sensors will continue to read and adjust the A:F ratio as normal but since the downstream O2 sensors will detect that there are no cats, they'll trip the CEL. You can either have the downstream O2 sensors disabled in the tune or install MIL eliminators to trick the ECU.
Very Helpful thank you. i’ll make sure to get some MIL eliminators
 

racerraj

Founding Member
Dec 17, 2001
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Dickson, TN
I've run over 150,000 miles without cats and without a tune. CEL light on the whole time. Car has 290,000+ miles on it, no troubles from no cats.
 

Bullitt95

10 Year Member
Jun 13, 2007
1,609
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Cyprus
www.angelfire.com
I've run over 150,000 miles without cats and without a tune. CEL light on the whole time. Car has 290,000+ miles on it, no troubles from no cats.

That's good to know. The only thing is that with the CEL on the whole time, how will you be alerted if a new problem develops unless it affects the way the car drives?
 

racerraj

Founding Member
Dec 17, 2001
493
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Dickson, TN
I would not not be notified. I used to use the "Torque" app on my phone and check now and then. Now I have an Android Head Unit and I set Torque to Auto-Start. It runs a dash I set up, but once or twice a week I run a scan (Real easy now). The dash I created shows about all my sensors, so if something was amiss, I would likely catch it. But I went at least 100,000 miles without that and never had an issue just doing infrequent checks.

That's good to know. The only thing is that with the CEL on the whole time, how will you be alerted if a new problem develops unless it affects the way the car
 

cbxer55

Active Member
Jan 25, 2020
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Oklahoma
I have the EGR deleted on my 04 Lightning, CEL been on since July 2018. I just check it with my scanner every time I drive it to make sure nothing else is present. I've had a CEL on my 98 V-6 Ranger for so long, and for so many dang reasons, I gave up on worrying about it. Put a piece of black tape over the CEL and just keep driving it. I gave up trying to fix every dang thing that went wrong, and just am waiting for it to give me a reason to tow it to a Pick-A-Part. LMAO! It's my bad weather vehicle anyways.
 

Sycostang67

Member
Sep 27, 2019
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Kuna, ID
I'm thinking of going catless as well, but can't for the life of me find the MIL eliminators for my car. I can only find them for the 96-04 mustangs. Would those still work? I would rather not have the dash light on all the time, I'm kind of OCD about that sort of thing.
 

cbxer55

Active Member
Jan 25, 2020
279
60
38
59
Oklahoma
I'm thinking of going catless as well, but can't for the life of me find the MIL eliminators for my car. I can only find them for the 96-04 mustangs. Would those still work? I would rather not have the dash light on all the time, I'm kind of OCD about that sort of thing.

There's a company, WeaponR, that sells MIL eliminators. Having trouble opening their site where I am currently. I'll try again later.
 

Sycostang67

Member
Sep 27, 2019
34
23
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41
Kuna, ID
I went to the weaponR site, they have the tubes that put the sensor further from the pipe but they dont tell you what size sensor they are for. They just say universal. Is 18mm the universal size for 02 sensors?