Post-Tune Engine Stutter at Peak Torque

AnotherFK8

Member
First Name
Chris
Joined
May 20, 2020
Messages
29
Reaction score
9
Location
Sheffield, U.K.
Car(s)
FK8 C.W '18
Country flag
Hey guys,

Today I had my CTR tuned by a reputable U.K Honda tuner using Ktuner V1.2. End results were 386BHP and 353LBFT. During the post-tune street runs, the tuner noticed an audible/physical blip occurring at around 4200RPM, coinciding roughly with the peak torque point. Audibly it sounds like a click/hi-hat, almost like a small release of air. Physically it feels like a tiny stutter whilst going up the rev range. A week prior to the tune I had no choice but to fuel with 95 RON (91 RON US), the tuning team put it down to possibly having bad fuel not agreeing with the 98RON based tune. 95RON is the minimum suggested quality for the U.K.

Things Tried:
- Tune has been rechecked for inconsistencies. None found, tune is conservative and said to be safe.
- Flashing back to stock and retesting. No clicking or stuttering noted.
- Tank emptied as best as possible. Brimmed with 99RON, driven casually, then spirited, for 80+ miles in an attempt to flush remaining 95RON.
- Ktuner datalog shows a slight blip in AFR at suspect RPM (unbeknownst to me you have to actually save the log once you're done recording...doh...I will try again tomorrow and upload results along with dyno sheet). Regardless, AFR is always under 12, even during the blip.

Mods:
- HKS Legamax Exhaust.
- PRL HVI Intake (stock turbo inlet pipe).
- HKS Intercooler w/charge pipes.
- KTuner V1.2

Any help would be massively appreciated as always!



Advertisement


 
Last edited:

kefi

oh shit waddup its dat boi
Joined
Jan 8, 2020
Messages
580
Reaction score
537
Location
Central Florida
Website
fk8.clinic
Car(s)
2018 Type R
Build Thread
Link
Country flag
My first thought would be some sort of boost leak, especially with aftermarket charge pipes. Max torque generally means max air, so it would make sense that happens and it peeps out some air. Second thought would be you're hitting the fuel pump limit.

Check your boost levels and fuel pressure levels in the datalog for any sudden drops.

The only thing lower octane fuel would do is introduce knock, which you'd see on the KR charts followed by a loss of power. Otherwise it won't exhibit what you're experiencing.
 

aldksgo

Senior Member
First Name
Mark
Joined
Sep 4, 2019
Messages
311
Reaction score
165
Location
Ottawa, Ontario, Canada
Car(s)
'19 FK8 R-24920, '14 Civic EX Sedan Manual
Country flag
My first thought would be some sort of boost leak, especially with aftermarket charge pipes. Max torque generally means max air, so it would make sense that happens and it peeps out some air. Second thought would be you're hitting the fuel pump limit.

Check your boost levels and fuel pressure levels in the datalog for any sudden drops.

The only thing lower octane fuel would do is introduce knock, which you'd see on the KR charts followed by a loss of power. Otherwise it won't exhibit what you're experiencing.
I just installed charge pipes and was wondering this myself. Hasn't happened to me yet, but I was wondering what the symptoms of boost leak would be. Not able to reach max boost? way less boost? No boost at all?
 

kefi

oh shit waddup its dat boi
Joined
Jan 8, 2020
Messages
580
Reaction score
537
Location
Central Florida
Website
fk8.clinic
Car(s)
2018 Type R
Build Thread
Link
Country flag
I just installed charge pipes and was wondering this myself. Hasn't happened to me yet, but I was wondering what the symptoms of boost leak would be. Not able to reach max boost? way less boost? No boost at all?
With datalogs, boost having difficulty reaching or staying at the boost target, especially once spooled. Weird AFR or STFT fluctuations at specific PSI.

Note that our max boost can vary wildly based on environmental conditions, so you need to see what the ECU is actually trying to target in that moment rather than just looking at your dash.

Without datalogs, jumpiness at peak torque or low boost in general.

It's surprisingly easy to pinch some of the hoses to have a tiny little air gap.
 

aldksgo

Senior Member
First Name
Mark
Joined
Sep 4, 2019
Messages
311
Reaction score
165
Location
Ottawa, Ontario, Canada
Car(s)
'19 FK8 R-24920, '14 Civic EX Sedan Manual
Country flag
With datalogs, boost having difficulty reaching or staying at the boost target, especially once spooled. Weird AFR or STFT fluctuations at specific PSI.

Note that our max boost can vary wildly based on environmental conditions, so you need to see what the ECU is actually trying to target in that moment rather than just looking at your dash.

Without, jumpiness at peak torque or low boost in general.

It's surprisingly easy to pinch some of the hoses to have a tiny little air gap.
I'll have to do more datalogging.

I had some pulls yesterday after my inlet and charge pipes install and it was great. But I just sat in a drive through for what was probably 30+ minutes, and my boost was NOT GOOD :'( My poor poor IATs lol.

Saw my boost on the native display never get higher than 18psi and felt like a snail taking an on ramp just now. Chalked it up to my bad Wendy's experience though.
 

martindtjr

Senior Member
First Name
Martin
Joined
Jun 15, 2017
Messages
90
Reaction score
25
Location
San Diego
Website
www.flickr.com
Car(s)
TYPE R PMM 2019, Toyota Sienna XLE 2015, Scion Xa 2006
Vehicle Showcase
1
Country flag
Check all the intercooler hose clamps. It mabe stripped due to being an impact/or Dewalt.
Seen it would only leak during boost.
 

kefi

oh shit waddup its dat boi
Joined
Jan 8, 2020
Messages
580
Reaction score
537
Location
Central Florida
Website
fk8.clinic
Car(s)
2018 Type R
Build Thread
Link
Country flag
I'll have to do more datalogging.

I had some pulls yesterday after my inlet and charge pipes install and it was great. But I just sat in a drive through for what was probably 30+ minutes, and my boost was NOT GOOD :'( My poor poor IATs lol.

Saw my boost on the native display never get higher than 18psi and felt like a snail taking an on ramp just now. Chalked it up to my bad Wendy's experience though.
Datalogging is key. I'm working on remaking the megathread and including a section on what to look for in logs.

The max boost can be reduced SIGNIFICANTLY by IATs. 18 is low, but 30 mins of idling is enough to do it for sure until you actually get on the highway to cool it back down.
 

aldksgo

Senior Member
First Name
Mark
Joined
Sep 4, 2019
Messages
311
Reaction score
165
Location
Ottawa, Ontario, Canada
Car(s)
'19 FK8 R-24920, '14 Civic EX Sedan Manual
Country flag
Datalogging is key. I'm working on remaking the megathread and including a section on what to look for in logs.

The max boost can be reduced SIGNIFICANTLY by IATs. 18 is low, but 30 mins of idling is enough to do it for sure until you actually get on the highway to cool it back down.
Would LOVE that Kefi. I have a new datalog as I mentioned post inlet and charge pipe install but I don't know what I'm looking for quite yet, so trying to figure it out.

Yes, that drivethru murdered my IATs. Both were above 150F lol, and the on ramp was pretty close to the location so it was probably still only at 130-140. Just wanted to see what would happen but felt like a snail for sure!
 

kefi

oh shit waddup its dat boi
Joined
Jan 8, 2020
Messages
580
Reaction score
537
Location
Central Florida
Website
fk8.clinic
Car(s)
2018 Type R
Build Thread
Link
Country flag
Yeah, on factory and most of the 91/93 Hondata basemaps it'll reduce max boost by 10% past 140F/60C and 5% past 104F/40C. The PRL intercooler/downpipe map reduces this effect by roughly half, to only 5% and 2% respectively.

I'm not sure if it'll keep reducing any more past 60C. @Hondata could you chime in on that?

Stock/almost every basemap:
1594944675727.png


PRL Intercooler/Downpipe Hondata basemap (91 or 93):
1594944742158.png
 

aldksgo

Senior Member
First Name
Mark
Joined
Sep 4, 2019
Messages
311
Reaction score
165
Location
Ottawa, Ontario, Canada
Car(s)
'19 FK8 R-24920, '14 Civic EX Sedan Manual
Country flag
Yeah, on factory and most of the 91/93 Hondata basemaps it'll reduce max boost by 10% past 140F/60C and 5% past 104F/40C. The PRL intercooler/downpipe map reduces this effect by roughly half, to only 5% and 2% respectively.

I'm not sure if it'll keep reducing any more past 60C. @Hondata could you chime in on that?

Stock/almost every basemap:
1594944675727.png


PRL Intercooler/Downpipe Hondata basemap (91 or 93):
1594944742158.png
Interesting, as I'm also running on the PRL DP/IC map. It's about to be pouring rain so won't be going back out to test tonight but will see if it was indeed just because of the soak (probably) or if there was maybe an error.

Also, will start looking at my logs from last night to see how it is.
 

kefi

oh shit waddup its dat boi
Joined
Jan 8, 2020
Messages
580
Reaction score
537
Location
Central Florida
Website
fk8.clinic
Car(s)
2018 Type R
Build Thread
Link
Country flag
Interesting, as I'm also running on the PRL DP/IC map. It's about to be pouring rain so won't be going back out to test tonight but will see if it was indeed just because of the soak (probably) or if there was maybe an error.

Also, will start looking at my logs from last night to see how it is.
Yeah, even with the IAT2 reduction, 18psi is low. What do you normally see? The ECU is still not entirely figured out.

Keep in mind, this reduction is applied only to the atmospheric pressure-based max boost limit table and not your calculated boost targets nor the IAT2 limit table. Whichever limit is lower (IAT2 or PA) is used and then the IAT2 compensation table is applied if it's using the atmospheric limit.

You may have just hit this table's limits first:
1594945864428.png
 
Last edited:

aldksgo

Senior Member
First Name
Mark
Joined
Sep 4, 2019
Messages
311
Reaction score
165
Location
Ottawa, Ontario, Canada
Car(s)
'19 FK8 R-24920, '14 Civic EX Sedan Manual
Country flag
Yeah, even with the IAT reduction, 18psi is low. What do you normally see? The ECU is still not entirely figured out.

Keep in mind, this reduction is applied to the max boost limits and not your boost target.
I've only paid attention to my boost on the dash, not my hondata mobile and I haven't checked my datalog yet but I've seen it normally pretty high when I punch it, like 26-27? Not sure if it's just a thing with the native dash..

EDIT:

LOL man I'm trying to learn so I'm just waiting here to see what you have to say :D
 

kefi

oh shit waddup its dat boi
Joined
Jan 8, 2020
Messages
580
Reaction score
537
Location
Central Florida
Website
fk8.clinic
Car(s)
2018 Type R
Build Thread
Link
Country flag
I've only paid attention to my boost on the dash, not my hondata mobile and I haven't checked my datalog yet but I've seen it normally pretty high when I punch it, like 26-27? Not sure if it's just a thing with the native dash..
Native dash is reading the same sensors as datalog is.
 

Advertisement












Advertisement


Top