swapping mid tubes for longtubes,do I need to retune?
12-15-2011, 05:06 PM
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swapping mid tubes for longtubes,do I need to retune? Hey guys, I have a pretty stout street car with the mods listed in my sig. One question >>do I need to (without a doubt) get it redynoed and tuned from just swapping from Mac mid tube headers and y pipe with high flow cats, to a set of BBK long tubes and ORY?.It was professionally dyno tuned by a (extremely) awesome LS tuner. Just curious if I should go ahead and put them on, or wait till I can take it (2 hour trip) to get retuned..any help from subject matter experts would be appreciated.
Last edited by ilovechevy1; 12-15-2011 at 05:07 PM. Reason: im stoopid
12-15-2011, 06:35 PM
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Aneeeee tuning gurus out there who can answer this (simple) question. I'm not into all the tuning stuff with my car, only know what mods to do to make it go faster. I need alot of help when it comes to any type of computer tuning...please help
12-15-2011, 07:32 PM
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I'm not 100% sure on that, but it should be able to run and drive with out the tune. My tuner will tell you that no matter what to get the best performance out of the car you will need a re tune.
12-15-2011, 07:45 PM
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yeah, thanks for replying.I already have the headers and ORY in my posession and will prob be swapping them over to it this weekend. I'm just worried that it may throw my tune way off with there no longer being cats on the car. I have high flow Mac cats on it now (they came with the Y pipe and header bundle lol) .I just dont' want to floor my car letting boost and water/meth injection hit and it cause something to go wrong.
12-15-2011, 09:25 PM
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Hey guy's, if i can get anymore feedback on this tuning question then it will really help my decesion on wether to install these headers and ORY this weekend..thanks ahead for any input
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12-16-2011, 05:37 PM
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Yes that makes sense, but what about the fact that my current Y pipe has high flow cats, and the BBK ORY has no cats ( I'm not trying to insult you intelligence either). will having no cats throw some crazy code up causeing my car to act funny, I'm not 100% sure if my tuner dleted the cat code so that it will no longer pop up (I believe he done something like that tho).
12-17-2011, 06:37 AM
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Going from Mid's to LT's will cause a slightly higher flowing exhaust, make the tune "Way Off"? No, It should be close enough that the commanded A/F should still apply by the PCM. But if you want all the gains then of course a tune is not necessary but as said wouldn't hurt.
12-17-2011, 03:27 PM
#13
will having no cats throw some crazy code up causeing my car to act funny, I'm not 100% sure if my tuner dleted the cat code so that it will no longer pop up (I believe he done something like that tho).
I really hope someone who actually tunes cars jumps on here and says.
If you want to throw down the cash for a few extra hp then by all means go ahead and re-tune it. If you're ok with leaving a few hp on the table then save the $400.
12-18-2011, 09:12 AM
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You'll get codes for it, but nothing that will cause your cur to run bad at all.
Guess people with experience but not professional tuners are not good enough eh?
If you want to throw down the cash for a few extra hp then by all means go ahead and re-tune it. If you're ok with leaving a few hp on the table then save the $400.
Guess people with experience but not professional tuners are not good enough eh?
If you want to throw down the cash for a few extra hp then by all means go ahead and re-tune it. If you're ok with leaving a few hp on the table then save the $400.
12-18-2011, 02:59 PM
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Eliminating Cats will decrease backpressure and allow increased exhaust flow, which in turn will allow your motor to move more air and fuel. Your long term fuel trims will become positive instead of negative which will protect your engine from running too lean (unless you have switched to speed density mode in which case only install with a retune), but you will no longer have the precise AF ratio you had before during WOT operations. I would make the changes and enjoy the improved power and sound and when you can afford it eventually have it retuned so they can increase the higher RPM VEs, retune the MAF which will now be reading low at the higher RPM levels, and after the retune your PE vs RPM for WOT will be optimal again - until then it should be on the rich side because it will go into PE mode with positive LTFTs (this is good from an engine protection standpoint). Again, there is no reason to put off the installation just because you need to save up for an eventual retune to optimze performance and the changes you're making are not going to render a car that performs unfavorably.
Last edited by James Linder; 12-18-2011 at 03:04 PM.
12-18-2011, 07:33 PM
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Eliminating Cats will decrease backpressure and allow increased exhaust flow, which in turn will allow your motor to move more air and fuel. Your long term fuel trims will become positive instead of negative which will protect your engine from running too lean (unless you have switched to speed density mode in which case only install with a retune), but you will no longer have the precise AF ratio you had before during WOT operations. I would make the changes and enjoy the improved power and sound and when you can afford it eventually have it retuned so they can increase the higher RPM VEs, retune the MAF which will now be reading low at the higher RPM levels, and after the retune your PE vs RPM for WOT will be optimal again - until then it should be on the rich side because it will go into PE mode with positive LTFTs (this is good from an engine protection standpoint). Again, there is no reason to put off the installation just because you need to save up for an eventual retune to optimze performance and the changes you're making are not going to render a car that performs unfavorably.
12-19-2011, 09:01 AM
#17
Another wrote in about having better resolution by switching PCM's. I said explain what this better resolution you are talking about. He just wrote back and said that's what he heard and didn't know anything about that stuff. But he was giving advice.. So do your homework, keep on asking cause there are a lot of people on this forum that DO know what they are talking about..
12-26-2011, 02:14 AM
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n/a wouldnt matter as much , being boosted , you run a big risk of the afr(air fuel ratio) being off , and possibly enough to hurt the motor
if you arent gonna be beating on the car , or racing it , you should be ok , tunning it will give you the best and make sure everything stays in a safe range
one of the reasons you get hit or miss answers is no one really knows each car will react to the changes , one car could stay the same , another go to rich or to lean , stock tunes usually err on the rich side , and headers and freer flowing intakes usually lean them up while still being in a safer range , where boost needs a larger cushion to be in a safer range
if you arent gonna be beating on the car , or racing it , you should be ok , tunning it will give you the best and make sure everything stays in a safe range
one of the reasons you get hit or miss answers is no one really knows each car will react to the changes , one car could stay the same , another go to rich or to lean , stock tunes usually err on the rich side , and headers and freer flowing intakes usually lean them up while still being in a safer range , where boost needs a larger cushion to be in a safer range
12-27-2011, 01:10 PM
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thanks for all the help, I do believe I will be wait to put them on a few days before I take it to get tuned. Anything longer and I would be tempted to punch it , and it may cause problems I'm not financially able to repair atm lol
