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Headers and tune?

15K views 40 replies 17 participants last post by  VNMOUS1 
#1 ·
I already have a lethal o/r h pipe, when i install new arh long tube 1 7/8 headers with 3 inch o/r h pipe back to factor 2 1/2 piping will i need a retune for running safely without causing damage?

Also retune for maximum gains right?
 
#5 ·
Gosh...I would if I could, but I don't have any first-hand experience with this type of mods. I've heard that long-tube headers don't really make enough difference to warrant the trouble and expense, so I wouldn't think you'd need a retune. Have some patience, somebody with more performance knowledge will chime in and give you a more specific answer. You might want to email BJ at VMP....he is always helpful.
 
#9 ·
Just my 2cents, but when you add headers you are changing the pressure and resistance in the engine so that will inherently change the air fuel mixture. Also don't forget you are relocating the cats from stock or in the case of an off road pipe, you are removing them completely which will significantly change the back pressure in the system. Also remember depending on what year car you have, the O2 sensors are wide band or not. I would say you definitely need to talk to BJ'S at VMP for a returned. Better then finding out the hard way that the mixture is way off.
 
#10 ·
I am a tuner.
That being said, you do not need to retune for adding headers only. However, there is one 2-dimensional table that is usually changed with the addition of headers but many tuners don't even bother to take the time to do this. It is called the O2 Sensor Transport Delay table. Because the O2 sensors are moved further downstream with headers, this table is supposed to address this by adding time to the entire table. Typically, I multiply all table values by 1.4 or 1.5. But I can tell you that not doing this will not affect O2 function or anything else as far as I can tell.

Also, keep in mind that the PCM has the ability to adjust fueling up to 25 percent rich or lean, which is a huge amount. So if adding headers results in a richer or leaner condition, the PCM adjusts and you will never know the difference.

As for wideband sensors, it can be relocated without affecting it, as long as it remains upstream of the cat.
 
#13 ·
it is a pain for sure, I dropped the k member, lots of work..... and I have a lift.... good luck getting it finished up. Exhaust wise, I had the KR axle backs, WAY too loud, added some 12 in dynomax resonators,....been driving it now for a few months.... still too loud and raspy for me (and I like loud!). I took BJ's advice and got the Borla Touring exhaust, its on the bench right now, may start tonight.
 
#15 ·
So based on Willie's comment if you're running the stock headers with an off-road H pipe does that require a tune? I know how to get rid of the check engine light on the dash... Just want to make sure that doesn't require a tune. I'm specifically talking about a 2013 GT500. I really don't want to do a tune until I start other mods on the car so if it requires a tune I will hold off on the H pipe.

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#16 ·
You should. You can get by without one, but you should turn off cat protection and the rear O2 sensors. A tune on your car can go a long way toward mods. On a basic tune, many of the loads tables can be changed to accommodate a pulley change that might occur at a later date. But a larger CAI or a change in injectors will require an update. VMP will make tune adjustments for free if you buy the parts from them.

Willie is right on for the header update question.
 
#22 ·
Can't believe I have not subscribed yet
 
#23 · (Edited)
I had always been told and read that headers need a tune update. On my 2011 I saw things lean out a little before the tune update. Granted I did not give it the 20 miles it needs to learn so maybe it would have fattened back up.

The install is a pain, literally. You should not need to lower the K but it does help to lift the motor and remove the mounts and starter. Expect some raw knuckles when you are done.

If you unbolt the K, use some marker paint to mark where it was positioned so you can avoid a trip to the alignment shop. When I lowered my K, I put a number of dots on the K and the chassis, when I bolted it back up using those marks the alignment was spot on.
 
#32 ·
From what bj told me a few weeks ago they are working on it.

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#33 ·
I think that's where we're headed, ultimately. If the Federal government can assess civil money penalties against auto manufacturers for emission violatons, I don't know why they couldn't assess them against tuners or the end user. Seems there are at least a dozen states that have adopted CARB standards too.
 
#34 ·
Yep...And more on the way...

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#35 ·
There have been a number of small tuning shops put out of business in the past year due to violations of the Clean Air Act. Keep in mind, that is Federal, not California.

Yes, we are working on mods with calibrations to be granted an Executive Order and become CARB compliant.

Anyone that doesn't follow these simple rules these days are putting their futures in jeopardy.

bj
 
#36 ·
Just to bump this up to the top again, I just got headers and was informed that my computer will "learn" the o2 delay, and my tune for stock manifolds will be fine for headers, never heard of the o2 sensor learning thing.
 
#38 ·
I will assume it wasn't anyone in our company that told you that. If so, there may be a misunderstanding.

The O2 delay has to be done in the tune and really can't be done on the wideband cars like it was 07-10.

As O2s age/degrade the time will need to be delayed further and you will reach a wall that allows no further adjustment. Then you will get O2 heater codes.

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