Sputtering and Farting after Downpipe Install

Nora

Member
Joined
Nov 28, 2020
Messages
13
Reaction score
0
Location
Panama
Car(s)
2019 Civic 1.5T CVT
Country flag
Hello, I am a newbie when it comes to exhaust systems but since I modified my whole exhaust there are few things concerning me:
My setup is PRL Frontipe+Race Downpipe(catless), Race Muffler and 3” straight. Sometimes at cold starts the exhaust begins to sputter the first 30 seconds and then clears out (I think this is product of condensation taking place). And always after shutting the car off there’s a farting sound like if the car just gave its last breath (sometimes it’s a louder sound). Also at low load (1k-2k rpms) the car sometimes hesitates like if it’s having a hard time to breathe, it’s more noticeable when going uphill, this does not happen at high load. I know it requires tuning, but I have not got a chance to take it to a professional tuner, I cleared the CEL using Ktuner by disabling secondary o2. So my question is, Is it because I haven’t tuned it yet that’s causing this?

My mechanic says that this is normal, that I don't have to worry about it. But I need someone who has experienced this and assure me everything is okay..

Sorry for my ineptitude.





Advertisement

 
Last edited:

Nick D

Member
Joined
Jul 19, 2020
Messages
42
Reaction score
57
Location
Washington State
Car(s)
2020 civic si coupe
Country flag
You have a ktuner but are not tuned?

Clip of the sound?

data log?

What you are describing doesn't sound that strange to me with a catless downpipe.
 
OP

Nora

Member
Joined
Nov 28, 2020
Messages
13
Reaction score
0
Location
Panama
Car(s)
2019 Civic 1.5T CVT
Country flag
  • Thread starter
  • Thread Starter
  • #3
You have a ktuner but are not tuned?

Clip of the sound?

data log?

What you are describing doesn't sound that strange to me with a catless downpipe.
I am just remapped to the Dual Factory/21psi Map, but nothing more.

Here’s a cold start, I think you can hear very low pops or is it my imagination?:
















Here’s me revving to 2krpms and letting go; you can hear kind of a fart:

















and here’s the shut off; again a fart sound like giving its last breath or getting compressed air out, this usually gets louder after a drive:

















Right now I cannot provide any datalog as my laptop is very dead, can’t have it on without charger connected. But from what I can see from my Tunerview readings everything seems normal IMO. Only thing I noticed sometimes STFT would jump to -10% -15% and knock control would rise to .52 at Stop and Go, as where I live there is a lot but a lot of speed bumpers, you would get a one every minute of drive. Also is it normal at idle I get a gas-like smell coming from the downpipe itself? But not at the exhaust end?
 
Last edited:

USNengineman

Senior Member
Joined
May 1, 2020
Messages
267
Reaction score
114
Location
NV
Car(s)
2020 civic si coupe
Country flag
I am just remapped to the Dual Factory/21psi Map, but nothing more.

Here’s a cold start, I think you can hear very low pops or is it my imagination?:
















Here’s me revving to 2krpms and letting go; you can hear kind of a fart:

















and here’s the shut off; again a fart sound like giving its last breath or getting compressed air out, this usually gets louder after a drive:

















Right now I cannot provide any datalog as my laptop is very dead, can’t have it on without charger connected. But from what I can see from my Tunerview readings everything seems normal IMO. Only thing I noticed sometimes STFT would jump to -10% -15% and knock control would rise to .52 at Stop and Go, as where I live there is a lot but a lot of speed bumpers, you would get a one every minute of drive. Also is it normal at idle I get a gas-like smell coming from the downpipe itself? But not at the exhaust end?
every single sound i heard in these videos sounds like my exhaust a bit. Im 27won catted dp with resonator delete on stock exhaust on my Si. It doesnt trip me up one bit. you NEED to log if youre really worried man. I dont have any misfires or fuel trims out of wack on start ups or at all for that matter. So before next time you start the car, turn it on to the accessory mode or whatever its called but dont START the car, wait for your ktuner to load, start a data log and then start the car until your coolant reaches around 150ish, thats hot enough i like to think. and then after you stop the data log, unplug your ktuner and bring it inside to plug into your laptop, the data log saves to the tuner itself. load that puppy up and people will be able to answer your concerns better my guy!!!
 
OP

Nora

Member
Joined
Nov 28, 2020
Messages
13
Reaction score
0
Location
Panama
Car(s)
2019 Civic 1.5T CVT
Country flag
  • Thread starter
  • Thread Starter
  • #5
every single sound i heard in these videos sounds like my exhaust a bit. Im 27won catted dp with resonator delete on stock exhaust on my Si. It doesnt trip me up one bit. you NEED to log if youre really worried man. I dont have any misfires or fuel trims out of wack on start ups or at all for that matter. So before next time you start the car, turn it on to the accessory mode or whatever its called but dont START the car, wait for your ktuner to load, start a data log and then start the car until your coolant reaches around 150ish, thats hot enough i like to think. and then after you stop the data log, unplug your ktuner and bring it inside to plug into your laptop, the data log saves to the tuner itself. load that puppy up and people will be able to answer your concerns better my guy!!!
Thanks! I will be trying this tomorrow, I must enable onboard logging am I right?
 

rileyj98

Senior Member
First Name
riley
Joined
Mar 7, 2019
Messages
71
Reaction score
51
Location
Chilliwack, BC
Car(s)
2018 civic coupe
Country flag
Sounds like gas burning in the exhaust itself, with it being catless and not running off the secondary o2 its going to run rich, so the excess fuel is going into the exhaust that isn't fully combusted and then burning in the exhaust causing the pops that is being heard
 

USNengineman

Senior Member
Joined
May 1, 2020
Messages
267
Reaction score
114
Location
NV
Car(s)
2020 civic si coupe
Country flag
Thanks! I will be trying this tomorrow, I must enable onboard logging am I right?
im pretty sure as long as you hit start data log itll start a log. ive never had to enable anything
 

ryanfk7

Senior Member
First Name
Ryan
Joined
Jul 23, 2017
Messages
124
Reaction score
81
Location
PA
Car(s)
Honda Civic ‘17 Hatch EX
Vehicle Showcase
1
Country flag
@rileyj98 is correct. I had a catless dp, fp, and 3” exhaust. Sounded almost exactly like this on cold starts at first install. You’re running super rich with any base map...which are better than nothing, but when pushed hard it can cause failures. I’d just take it easy and say you don’t have anything to worry about now. I think I ran base map for 1-2 months before I could get in to have it done right. You’re numbers are normal for the current situation
 

USNengineman

Senior Member
Joined
May 1, 2020
Messages
267
Reaction score
114
Location
NV
Car(s)
2020 civic si coupe
Country flag
Sounds like gas burning in the exhaust itself, with it being catless and not running off the secondary o2 its going to run rich, so the excess fuel is going into the exhaust that isn't fully combusted and then burning in the exhaust causing the pops that is being heard
any reasoning behind my exact sounds doing the same with the secondary 02 sensor??
 

ryanfk7

Senior Member
First Name
Ryan
Joined
Jul 23, 2017
Messages
124
Reaction score
81
Location
PA
Car(s)
Honda Civic ‘17 Hatch EX
Vehicle Showcase
1
Country flag
I found it. This was with Megan Racing Catless Dp/Fp, with BLOX exhaust after install with KTuner base dual factory/21psi
 

vandalSI

Senior Member
First Name
Nick
Joined
Sep 16, 2019
Messages
322
Reaction score
410
Location
kansas city
Car(s)
2017 civic Si sedan
Country flag
are you running an aftermarket intake with a diff size maf? you shouldn't need to change maf scaling on stock intake.
 
OP

Nora

Member
Joined
Nov 28, 2020
Messages
13
Reaction score
0
Location
Panama
Car(s)
2019 Civic 1.5T CVT
Country flag
  • Thread starter
  • Thread Starter
  • #12
are you running an aftermarket intake with a diff size maf? you shouldn't need to change maf scaling on stock intake.
I was running that rich with stock intake and stock maf scaling, there are some cars like EUDMs and Italian versions where it overshoots at WOT and need adjustment
 
Last edited:
OP

Nora

Member
Joined
Nov 28, 2020
Messages
13
Reaction score
0
Location
Panama
Car(s)
2019 Civic 1.5T CVT
Country flag
  • Thread starter
  • Thread Starter
  • #13
Here are two logs, both with dual factory/21psi basemap, one with the factory maf scale running super rich, and the other one with a scaled maf that a friend of mine shared with me because the scaled one Ktuner offers does not help at all. The second one shows a full drive from startup, made some pulls but couldn't make it consistent because of traffic.
Can you guys notice something strange in my second log? Do I need to keep worrying about the sounds I get from the exhaust?
 

gtman

Senior Member
First Name
Mitch
Joined
Oct 27, 2015
Messages
10,457
Reaction score
13,668
Location
USA
Website
www.civicx.com
Car(s)
2017 Cosmic Blue EX-L Sedan
Vehicle Showcase
2
Country flag
I tried downloading your datalogs yesterday. When I went to open them, they were "invalid".
 

Advertisement






Advertisement
Top