P0101 + P0172, hesitation on light accel when cold – CST4 / big FMIC setup (logs inside)

[3mps_NL]

What’s up guys,

Looking for some input from people who’ve dealt with big turbo MPS setups. I’m chasing an issue that feels tuning/airflow related, not a failed part.

Car:
2011 Mazdaspeed 3
Forged motor

Mods:

CST4 turbo

CorkSport Stage 2 intake

CorkSport HPFP internals

Stock injectors (new / tested)

Airtec Stage 3 FMIC + piping

GFB BPV (full recirc)

EGR delete

Damond Stage 2 PCV plate

Dual Damond catch cans (vented)

Cobb downpipe

VersaTune custom tune by Justin Heath (WIP)

Issue

Hesitation / throttle pull feeling during light acceleration from low speed (roundabouts, corner exits).
Happened once during steady cruise around ~100 km/h with very light throttle.

Seems to occur mostly when the engine is cold.

No misfires, no popping, no black smoke.
Occasional fuel smell. Some white smoke which looks like condensation.

Codes

P0101 – MAF range/performance (current)

P0172 – System too rich, bank 1 (pending)

Logs (cold engine, light accel / cruise)

Typical values when hesitation happens:

RPM: ~2k–2.8k

Throttle: ~18–30%

Boost: 0–3 psi

MAF: ~8–15 g/s

Commanded AFR: ~12.5–13.0

Actual AFR: ~11.0–11.5

STFT: -10% to -18%

LTFT: -8% to -12%

HPFP pressure: stable / normal

No KR observed

During light cruise:
AFR stays richer than commanded, trims stay negative, eventually P0101 + P0172 set.

What’s been ruled out

OEM Mazda MAF

Multiple known-good MAFs tested (same result)

Injectors confirmed good

No obvious boost leaks found so far

Thoughts / suspicion

MAF scaling not fully dialed for CS S2 intake

Low RPM airflow instability with CST4 + large FMIC

Transient fueling during boost onset

Recirc BPV behavior at low load

Cold start enrichment + EGR delete pushing it rich

Possible influence of vented catch cans on measured airflow

Questions

Anyone seen P0101 + P0172 together due to MAF scaling / transient fueling on big turbo cars?

Recirc BPV causing rich spikes at light throttle?

Known effects of vented catch cans on MAF readings during cold operation?

Any specific log channels you’d want to see to confirm this?

Trying to avoid throwing parts at it. Any input appreciated.

 

[Easter Bunny]

You need an air straightener in the intake does the cs one have one?

 

[Crazycanadian]

What’s up guys,

Looking for some input from people who’ve dealt with big turbo MPS setups. I’m chasing an issue that feels tuning/airflow related, not a failed part.

Car:
2011 Mazdaspeed 3
Forged motor

Mods:

CST4 turbo

CorkSport Stage 2 intake

CorkSport HPFP internals

Stock injectors (new / tested)

Airtec Stage 3 FMIC + piping

GFB BPV (full recirc)

EGR delete

Damond Stage 2 PCV plate

Dual Damond catch cans (vented)

Cobb downpipe

VersaTune custom tune by Justin Heath (WIP)

Issue

Hesitation / throttle pull feeling during light acceleration from low speed (roundabouts, corner exits).
Happened once during steady cruise around ~100 km/h with very light throttle.

Seems to occur mostly when the engine is cold.

No misfires, no popping, no black smoke.
Occasional fuel smell. Some white smoke which looks like condensation.

Codes

P0101 – MAF range/performance (current)

P0172 – System too rich, bank 1 (pending)

Logs (cold engine, light accel / cruise)

Typical values when hesitation happens:

RPM: ~2k–2.8k

Throttle: ~18–30%

Boost: 0–3 psi

MAF: ~8–15 g/s

Commanded AFR: ~12.5–13.0

Actual AFR: ~11.0–11.5

STFT: -10% to -18%

LTFT: -8% to -12%

HPFP pressure: stable / normal

No KR observed

During light cruise:
AFR stays richer than commanded, trims stay negative, eventually P0101 + P0172 set.

What’s been ruled out

OEM Mazda MAF

Multiple known-good MAFs tested (same result)

Injectors confirmed good

No obvious boost leaks found so far

Thoughts / suspicion

MAF scaling not fully dialed for CS S2 intake

Low RPM airflow instability with CST4 + large FMIC

Transient fueling during boost onset

Recirc BPV behavior at low load

Cold start enrichment + EGR delete pushing it rich

Possible influence of vented catch cans on measured airflow

Questions

Anyone seen P0101 + P0172 together due to MAF scaling / transient fueling on big turbo cars?

Recirc BPV causing rich spikes at light throttle?

Known effects of vented catch cans on MAF readings during cold operation?

Any specific log channels you’d want to see to confirm this?

Trying to avoid throwing parts at it. Any input appreciated.

What does the guy tuning the car say about the problem?? 9 time out of 10 people come asking for information on what they think is the problem, but they haven't talked to guy doing the tuning..

When it comes to logs, you need Actual EQ (Or AFR), Desired EQ (or AFR), MAF g/s, Map, Short term and long term trims ,rear O2 voltage, RPM, APP, TPS and Waste gate duty cycle. High pressure fuel pressure actual and desired is helpful as well.. This is a lot for Versatuner to log all at once..

Cold start, let it idle for a good 5 or so min, drive it 10 to 15 min. light throttle, medium throttle, if you can some WOT. Smooth throttle movements are important. 3rd and 4th gear stuff works the best.

On a separate log.. RPM, TPS, APP, Coolant temp, intake air temp and boost air temp MAF air flow, MAP or/and BARO. Key on, Engine off. Make sure this is your first log before you start up the car.. We are verifying some basic sensor stuff here.

 

[Enki]

What does the guy tuning the car say about the problem?

Just as important: What stage of tuning are you on? Did you just install the parts and toss a random map on there, or have you "finished" tuning with your current tuner?
Also, who is your tuner?

 

[3mps_NL]

What does the guy tuning the car say about the problem?? 9 time out of 10 people come asking for information on what they think is the problem, but they haven't talked to guy doing the tuning..

When it comes to logs, you need Actual EQ (Or AFR), Desired EQ (or AFR), MAF g/s, Map, Short term and long term trims ,rear O2 voltage, RPM, APP, TPS and Waste gate duty cycle. High pressure fuel pressure actual and desired is helpful as well.. This is a lot for Versatuner to log all at once..

Cold start, let it idle for a good 5 or so min, drive it 10 to 15 min. light throttle, medium throttle, if you can some WOT. Smooth throttle movements are important. 3rd and 4th gear stuff works the best.

On a separate log.. RPM, TPS, APP, Coolant temp, intake air temp and boost air temp MAF air flow, MAP or/and BARO. Key on, Engine off. Make sure this is your first log before you start up the car.. We are verifying some basic sensor stuff here.

Thanks a lot for your reply,

I talked to the tuner about it, and got no clear answers. He was telling me to take a look at things i just replaced (since i replaced alot of parts thinking this might be the problem) we also did some maf calibration which did not resolve the problem.
Im at the point my knowledge about the car and possible solutions is running out, since im not a mechanic or tuner.
The car runs good most of the times so its also not a problem thats always there.

I did some logs to confirm the problem and also got the hessitations in a log (forgot which file it was on) and showed the tuner.

Im almost at the point of looking for another tuner, but dont know if the problem in tuning related.

Why im hoping to find someone who can tell me if it is.

 

[Enki]

Post logs, name tuner.