CSL Airbox Hesitation

[dl.m3]

Alright, just got the Turner airbox installed and running alphaN tune. I have a hesitation that occurs when I want to downshift rev-match, where I clutch-in, stab the throttle, and then the car sounds like to struggles to raise the rpm unless you hold the gas down for 1 second then it finally blips. Typically occurs after you coast for a few seconds before downshifting.

I recall reading about this on the old m3forum csl airbox hesitation thread. So I wonder if it was ever resolved or just a normal behavior or a MAF-less setup with a large plenum opening?

Please share your knowledge.

For the record. After I went with a MSS54HP, added a MAP sensor, and flashing Terra's csl clone binary. This issue was resolved. I can rev match downshift again!

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[T-Rex]

I still get hesitation running the full CSL software on an MSS54HP and using a MAP sensor.

Did you ever resolve this? I finally got my Turner box up and running last night on a Kassel-converted and tuned CSL HP DME with their MAP solution, and it has quite a bit of hesitation / unwillingness to rev. Any thoughts are appreciated!

[Good]

Bump, any new info on this topic? I've had this issue ever since I installed CSL airbox. Had Hassan dyno tune the car and it still is happening. I'm wondering if I install a map sensor, or replace O2 sensors

[Slideways]

Bump, any new info on this topic? I've had this issue ever since I installed CSL airbox. Had Hassan dyno tune the car and it still is happening. I'm wondering if I install a map sensor, or replace O2 sensors

Can you describe the hesitation in more detail? Is it sudden off/on throttle or somewhere in the rev range as the revs climb?

[Pavlo]

Did you ever resolve this? I finally got my Turner box up and running last night on a Kassel-converted and tuned CSL HP DME with their MAP solution, and it has quite a bit of hesitation / unwillingness to rev. Any thoughts are appreciated!

As mentioned before, I think this is part of the AFR problem that is on every MAF-less setup: it has to be custom tuned at all load and rev ranges, not just wide open dyno pulls. Get an LC2 and Testo and I think you'll find your answers pretty quickly.

[T-Rex]

As mentioned before, I think this is part of the AFR problem that is on every MAF-less setup: it has to be custom tuned at all load and rev ranges, not just wide open dyno pulls. Get an LC2 and Testo and I think you'll find your answers pretty quickly.

Agreed; after I went to an HTE tune all my issues were resolved! AFR gauge and logging are on my modlist for when I go E85 😎

[Good]

Hassan solved my issues! Purchase an AFR sensor and have him tune the car. There will be some compromise at certain rpm but without a map sensor Alpha N won’t be perfect.

[0-60motorsports]

That’s great to hear. So what’s the cheapest of an afr measuring tool?

[Good]

That’s great to hear. So what’s the cheapest of an afr measuring tool?

I used this one, worked great!

AEM (30-4110) UEGO Air/Fuel Ratio Gauge https://www.amazon.com/dp/B00N3VGPYS...NC5YWHETE7RQ45


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[0-60motorsports]

I used this one, worked great!

AEM (30-4110) UEGO Air/Fuel Ratio Gauge https://www.amazon.com/dp/B00N3VGPYS...NC5YWHETE7RQ45


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Ok and where do you screw in the sensor? I am thinking a dunk session would cost the same for me in bahrain as they have an AFR sensor already

[Good]

Ok and where do you screw in the sensor? I am thinking a dunk session would cost the same for me in bahrain as they have an AFR sensor already

I did a dyno session, in which Hassan perfected full throttle afr’s. I then did a few hours tuning on road with the AEM afr sensor which I simply installed into my Supersprint headers secondary o2 bung and routed outside the car into passenger seat directly into the fuse box for power. I do not have the need to keep an afr sensor in my car so I used this temporary method to fine tune for the road.

[0-60motorsports]

I did a dyno session, in which Hassan perfected full throttle afr’s. I then did a few hours tuning on road with the AEM afr sensor which I simply installed into my Supersprint headers secondary o2 bung and routed outside the car into passenger seat directly into the fuse box for power. I do not have the need to keep an afr sensor in my car so I used this temporary method to fine tune for the road.

Excellent. Good idea, thanks

[Good]

Excellent. Good idea, thanks

I would highly suggest installing a map sensor prior to tuning. See with Alpha N you will need to compromise low end hesitation to have smooth rev matching at 2500-3000rpm blips. You will only feel this hesitation if you are driving low rpm in a higher gear around town however.


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[0-60motorsports]

I would highly suggest installing a map sensor prior to tuning. See with Alpha N you will need to compromise low end hesitation to have smooth rev matching at 2500-3000rpm blips. You will only feel this hesitation if you are driving low rpm in a higher gear around town however.


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I am already HTE tuned and am on full OE CSL setup with everything and anything installed already LOL.

I was asking as HAsan always tells to get an afr device to fine tune but I’m happy with his tune. I’ll probably just dyno tune it one day and that’s it.

[SliM3]

The best way to solve this issue is by adjusting K_HFM_TI_RATE (current value is 22.4 grams/min; for ref. mine is set to 17.45 grams/min because of larger injectors). It provides a base injector pulsewidth when accel enrichment is triggered by throttle plate opening (DKBA = Drosselklappen Beschleunigungsanreicherung). It is a feedforward operation and is not influenced by any other fuel map filtering, however it does reference the limp home map (alpha-n) to calculate throttle opening delta's (current setting vs. target setting).

This issue is usually tackled by adjusting the KF_DKBA_SOFT_RF_N and KF_DKBA_HARD_RF_N maps on US/Euro versions, based on either a B_DYN_SOFT or B_DYN_HARD condition. CSL tune has a different load and fuel calculation so those maps won't do much in this instance.

Here is the calculation:
dkba_ti = dkba_ti_roh * dkba_tmot * KF_DKBA_HARD_RF_N (rf_roh,n)

dkba_ti = calculated final fuel enrichment
dkba_ti_roh = calculated raw fuel enrichment (calc'd from dkba_ti_roh = rf_delta * rf_ti_const)
rf_ti_const = calc'd from K_RF_HUBVOLUMEN * K_RF_LUFTDICHTE * K_HFM_TI_RATE * 60
dkba_tmot = KL_DKBA_TMOT (engine temp).



Hope this helps the DIYer's.