Performance after muffler install

Hello lads, have a question about something i noticed after having a magnaflow muffler installed on my truck. So, seems like immediately after the install i noticed that while driving around in town in OD when the truck shifts from 4th, there is a shudder. Feels like it’s shifting too soon and at lower RPM. Also, seems to hunt for gears on the highway. Seem to have lost high end torque. This is the best i can describe it. Has anyone else experienced this? I’m inclined to install a CAI in hopes of resolving this. Keep thinking it may have something to do with the intake? Idk.

 

Don't bother with the CAI, your truck already has the OEM CAI system.

The muffler install and the shudder/shift issue are coincidental to the muffler install. Exhaust is completely separate and isolated from the transmission.

Suggest to check the fluid level in the transmission or do a fluid/filter change.

 

Yes, i understand that the transmission and exhaust are completely separate. The second gens also have a sealed transmission. I think i was meaning to ask if the change in airflow may have somehow also changed either fuel/air ratios. I do perform all my own maintenance and am pretty observant as to fluids leaking and the way it behaves after modifications. Slight OCD

 

Id try to find someone near you with a stock exhaust and swap back to see what happens. Id try to isolate the problem before buying a CAI as you would be introducing another variable into the equation.

 

That’s an idea. I was also thinking of possibly just going back to oem if nobody here had any ideas. Really do enjoy the exhaust note, tho…

 

Did you reset your ECU (disconnect the battery for 3 minutes or longer) after doing the muffler swap? if not, that's where i'd start.

 

I don’t think i did that. Wasn’t sure it would’ve been necessary but, doing it NOW. Thanks for that!

 

Well, that seemed to have done the trick!! Unplugged the neg terminal, waited 20 mins, and reconnected. Just got back from a quick drive on the highway, and back home. Issue is resolved. Much love for this site. Thank you.

 

That's also what I do after every oil change, as well as MAF sensor cleaned, and clean or recharge filter (cai)
I didn't see the details of your exhaust, but I'm running an "X"-pipe, into 2 straight Magnaflow mufflers. I love it. All that cleaning, along with the throttle body, all make a difference when cleaned. I also did the coolant bypass; where you reroute the coolant hose to avoid going into the throttle body. (LS trick).
Anyway, hops you get some ideas and get to better enjoy your exhaust...

 

What's the point of bypassing the coolant lines in the TB?

 

Coolant lines are through the TB for winter time to avoid sticking/freezing. In summer, it's certainly not needed- and hot coolant flowing through the TB can lead to higher IAT's. Higher IAT's = less power, as timing and fuel are pulled to prevent detonation.

 

Thanks dirtdigginjoe... Couldn't have said it any better myself.
Sorry Key-Rei, for not seeing your question, but it was answered well....

 

Even without the lines going through the TB heat soak under the hood will quickly bring the aluminum TB sitting right behind the radiator up to general under hood temps, infact I'd wager that disconnecting them makes no positive impact and could potentially cause it to actually run hotter, the coolant system is called the coolant system because it cools after all.

For reference after a 30 minute drive with ambient temp of 85°F and 75% humidity my TB with lines connected is only 158°F while the intake tube with an airflow straightener acting ad a heat sink right next to it is only 130° (and this doesn't account for the emissivity of the shiny aluminum tube surface so the temperature is more than likely at least 15° warmer than the reading) and that's by far the coolest thing in my engine bay, so less than a 30° difference at best under the hood.

I doubt 30° difference makes even a single HP or ft-lb difference where as a frozen TB or even frozen particles in the intake surge (factoring Bernoull's equation which honestly is a little beyond my mathematical ability right now but I'll trust the results I found in similar threads online) can happen well above freezing temperatures.

I mean, you do you, but I'd like to see some dino numbers.





In case you don't know what an airflow straightener is:



That honeycomb is roughly 30mm thick.

 

I think any difference in temperature you may find is just a Fluke.

 

That's all great info, but for me, residing in TX. heat, I don't worry much about freezing temps.
When it does get cold here, it's not for a prolonged amount of time.
I'm not saying this adds HP or TRQ, I just did this ole sku LS mod because I always remove snd and clean my tb, and by bypassing this, it saves lots of time and mess limitations....

 

I guess...

I just cleaned my TB when I did injectors and didn't have much issue letting it flop around on the hoses.

 

If the temp at your TB is indicative of what the internal airflow temp is, then yes. HP would be left on the table.

Again, assuming the intake air at the TB matched that of the TB, then the engine is ingesting less dense air. Which means less HP and TQ. Plain and simple. Manifold Air Density would go down, compared to if the TB section was as cold as the intake portion which is cooler. Or compared to of the coolant bypass left the TB cooler.

Manifold Air Density going down, translates to HP and TQ going down.

Heat kills power.