new exhaust instructions say disconnect battery? does it work?

[abager2]

gonna install my new gibson single cat back metal mulisha exhaust tomorrow and while looking at instructions it states that you should disconnect battery so that the trucks computer will re-learn its settings with the bigger, better breathing 4" exhaust...does this really work?? only thing ive seen in the last several years that gets re-set after batterys disconnected is my radio stations(sarcasm-sorry)....trucks a 2015 silverado scsb z71 with 5.3 engine... i thought these systems today all were self-learning after driving some miles..input??

[tnchevy]

I wouldn't disconnect it, just drive it and you will fine.

[abager2]

so they are all self learning now??

[SMiller]

so they are all self learning now??

Yes, don't waste your time disconnecting.

[abager2]

Thanks...couldnt imagine it would make any difference but im not to proud to ask...

[TenofMe]

Yes, don't waste your time disconnecting.

I completely disagree.

 

I installed my Borla exhaust and the truck ran terrible. Unhooked the battery for about 20 minutes, put the key in the ignition and turned it to fully discharge the capacitance on the computer. Removed the key and hooked the battery back up. Now it's back in learn mode. Drove it hard for about 500 miles. Now it runs better than it ever has.

 

What's 2 minutes to unhook the battery and hook it back up when you're done? Even the manual tells you to do it.

[abager2]

I completely disagree.

 

I installed my Borla exhaust and the truck ran terrible. Unhooked the battery for about 20 minutes, put the key in the ignition and turned it to fully discharge the capacitance on the computer. Removed the key and hooked the battery back up. Now it's back in learn mode. Drove it hard for about 500 miles. Now it runs better than it ever has.

 

What's 2 minutes to unhook the battery and hook it back up when you're done? Even the manual tells you to do it.

REALLY?? i have never heard to turn the key to discharge any capacitance on the computer...no big deal to try it i guess..

[abager2]

one strange note about installing the single out catback gibson metal mulisha exhaust on my scsb truck...installation was pretty straightforward other than the hanger on the front head pipe isnt in exactly the right spot so that the headpipe can mate flush with the exit of the catalytic converter...if you mate them flush for the ball clamp to seal them tight, the hanger is no way close to the rubber mount..i did get it close with several adjustments but an gonna have to cut it and reweld it to make it spot on....other thing was when i clamped the headpipe to the muffler with the enclosed u-bolt style clamp, i had trouble getting it tight enough..i was afraid the bolt would twist off, but i cranked it down and thought all was good....drove it, and really liked the sound..it was really deep and throaty sounding..didnt notice any v4 drone.....until, the next day when i fired it up and heard a buzzing like a heat shield was vibrating...crawl under truck and find that i did not have the u bolt tight enough and that the pipe was slipping and vibrating...this time i get my bigger ratchet out and tighten it even more and its no longer vibrating.....but it completely changed the tone and not as deep sounding... the resonance changed and i have v4 drone pretty bad....not sure what i can do about it...but its amazing the difference and shows how much exhaust tuning or even torquing clamps can make changes

[SMiller]

REALLY?? i have never heard to turn the key to discharge any capacitance on the computer...no big deal to try it i guess..

Something else to do is turn on the headlights and tap the brakes a few times.

[abager2]

Something else to do is turn on the headlights and tap the brakes a few times.

i dont see what it can hurt..thanks!!

[fondupot]

I mean, it takes like 5 seconds to disconnect the battery.

[newdude]

Disconnecting the battery is just a normal safety procedure for 95% of the repairs made to cars now a day. That is all.

[FishinJ]

I did not disconnect the battery when I changed my exhaust. Since I did not cut or disconnect any wires it's was not needed. There are not any wires even around the exhaust behind the cat. Truck started right up and ran perfect. Only difference was that it sounded a lot better.

[abager2]

I did not disconnect the battery when I changed my exhaust. Since I did not cut or disconnect any wires it's was not needed. There are not any wires even around the exhaust behind the cat. Truck started right up and ran perfect. Only difference was that it sounded a lot better.

i believe the thought behind this,is that by disconnecting the battery and draining the capacitance, that it will reset the pcm to adjust for the new air/fuel mixture because of the change in flow of the new less restrictive exhaust...i am not smart enough to say if it does or it doesnt...however, the instructions that came direct from gibson stated that it should be done...i did not do it..mine ran good with a much less rectricted feel in power and sounded much better...i have noticed something strange though, and that is with my shift points..havent driven enough to say exactly what its doing but it seems like it shifts firmer in 1st and 2nd and then shifts really quick from 3rd to 4th...that is in normal driving, and not getting into it real hard....i am gonna drive it a bit this evening and when i get home try the battery drain and see if theres a change..

[abager2]

update.. I talked to a great guy named victor a Gibson exhaust...he tells me it is important to disconnect the battery..but not just for 5 minutes...procedure as they would like customers is 1) disconnect battery and purge system by turning key, stepping on brakes etc. and leave disconnected for at least 2 hours if vehicle has been driven that day..idea is that the vehicle and sensors need to be cold......2) install exhaust per instructions, and on u-bolt clamp tightening one side til tight to cause crimp on pipe, then loosen it and rotate clamp 90 degrees and retighten both nuts til tight to create a crimp around pipe..3)after install, reattach battery cable and let truck idle until at normal operating temperature before driving...the computers on these trucks are very inticate and finicky....I will try this procedure in the next couple of days and see if it makes a difference....I have re-installed my factory exhaust because my truck seemed to not have enough back pressure..it was shifting strange and would stay in v4 mode to much...we will see if this does the trick, but according to them, its very important to unhook the battery..