Powder flat after 6000 rpm
Powder flat after 6000 rpm I am having trouble with tuning my new heads. Just installed lightly used 225 AFRs, milled 30 to 57cc, with Brian Tooly 650 springs. Running 100 octane. Motor is TSP 408 LQ9 with Texas Giant Cam (248/254, .615'/.622', with 114 LSA), Fast 92, NW 92, 100 MAF, Racetronix 42s, 1-78" LT, 3" True Duals. I have plat NOS system but am not using on these runs.
I really don't think it's valve float, but the motor stops pulling after ~6k. Any ideas? Help? Is it something in the injector parameters?
Thanks.
I really don't think it's valve float, but the motor stops pulling after ~6k. Any ideas? Help? Is it something in the injector parameters?
Thanks.
Things I see in the logs:
* Your S1 O2 sensors are lazy, which makes the fuel trims think you're running rich in closed loop, so the short term fuel trims are pulling fuel.
* But since the STFT's are making the LTFT's average negative, the fuel trims jump to 0 at WOT, so that's not causing the WOT fueling to be adjusted.
* You're showing 0-1* of spark retard at WOT, and you're getting 21-22* of advance even though your high octane table is calling for 24-28*. It looks like your IAT spark correction tables are pulling out the advance due to high air temps. Your IAT's are in the upper 130's to 140F range. Describe your induction tract in front of the throttle body and IAT sensor location.
* I suggest logging barometric kpa also so you can see the delta between atmosphere and intake kpa. The larger the delta, the larger of an induction restriction you have.
Questions about your calibration:
* What wideband sensor are you using to tune fueling and where is it installed in the exhaust? The sensor was recently open-air calibrated? It's calibrated in HPT correctly?
* What specific injectors are you using, and are you using known good injector data?
* Your stoich is 13.7 (I presume you know that to be accurate for your specific 100 octane fuel?) and you're commanding a 1.143 EQ ratio or .87 lambda across the entire RPM range, which means a 12.0 AFR at WOT, is that by design? For N/A you typically want lambda between .83 and .87. You might gain by leaning it out a bit.
* Your VE tables are an unusual shape, what method did you use to tune them?
* How did you determine that your motor likes 24-28* advance at WOT? More advance is not necessarily better, and the 'increase advance until I receive knock and then back it off a degree or so' method isn't perfect either.
* Your S1 O2 sensors are lazy, which makes the fuel trims think you're running rich in closed loop, so the short term fuel trims are pulling fuel.
* But since the STFT's are making the LTFT's average negative, the fuel trims jump to 0 at WOT, so that's not causing the WOT fueling to be adjusted.
* You're showing 0-1* of spark retard at WOT, and you're getting 21-22* of advance even though your high octane table is calling for 24-28*. It looks like your IAT spark correction tables are pulling out the advance due to high air temps. Your IAT's are in the upper 130's to 140F range. Describe your induction tract in front of the throttle body and IAT sensor location.
* I suggest logging barometric kpa also so you can see the delta between atmosphere and intake kpa. The larger the delta, the larger of an induction restriction you have.
Questions about your calibration:
* What wideband sensor are you using to tune fueling and where is it installed in the exhaust? The sensor was recently open-air calibrated? It's calibrated in HPT correctly?
* What specific injectors are you using, and are you using known good injector data?
* Your stoich is 13.7 (I presume you know that to be accurate for your specific 100 octane fuel?) and you're commanding a 1.143 EQ ratio or .87 lambda across the entire RPM range, which means a 12.0 AFR at WOT, is that by design? For N/A you typically want lambda between .83 and .87. You might gain by leaning it out a bit.
* Your VE tables are an unusual shape, what method did you use to tune them?
* How did you determine that your motor likes 24-28* advance at WOT? More advance is not necessarily better, and the 'increase advance until I receive knock and then back it off a degree or so' method isn't perfect either.
Thanks Jim! Appreciate the feedback and advice.
I have an idea based on your comments about intake tract. I had to trim the bellow to get it to fit. I think it may be letting air bypass at the 6 o'clock position. I'm going to check it out today.
- Wideband is on the drives header at the end of the collector just higher than level with the ground.
- Point taken on desired AFR. I'm going to vary the command and see how it behaves.
- VE tables are somewhat of a chop job. I need to spend more time on them since my head swap.
- Yeah, I used that approach looking for an answer to the lack of power at the top end. I'm going to pull back until I get the fuel figured out. Then go back and attack the spark.
Obviously my main issue is lack of patience and trying to speed up my tuning process.
Thanks!
I have an idea based on your comments about intake tract. I had to trim the bellow to get it to fit. I think it may be letting air bypass at the 6 o'clock position. I'm going to check it out today.
- Wideband is on the drives header at the end of the collector just higher than level with the ground.
- Point taken on desired AFR. I'm going to vary the command and see how it behaves.
- VE tables are somewhat of a chop job. I need to spend more time on them since my head swap.
- Yeah, I used that approach looking for an answer to the lack of power at the top end. I'm going to pull back until I get the fuel figured out. Then go back and attack the spark.
Obviously my main issue is lack of patience and trying to speed up my tuning process.
Thanks!
