New 408" on dyno, LS1edit Tuning, car acts like rev limiter 1500 rpm after WOT
09-21-2004, 02:00 PM
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New 408" on dyno, LS1edit Tuning, car acts like rev limiter 1500 rpm after WOT Alright...strapped down fresh 408" on the dyno.
When we make a pull (say starting at 3500 rpm) the car pulls hard, a/f right at 13.0:1 a/f ratio, and WHAM right at 5100-5200 rpm the car slams like it hit a rev limiter. When it hits, the a/f instantly goes off the chart lean like it shut off the injectors and the dyno loses the torque reading like it completely cut spark.
If i take the rpms up to 4500 to start, it does the exact same thing but about 5700-5800 rpm...
If i start at 5500 rpm it hits about 6200.
No matter what i do in ls1edit I cant get around it. What could cause the car to be pulling perfect then slam on a rev type "limiter "
We moved all the rev limiters up to 7200 and has no effect.
Car is 408, stock heads, big 238+ xe-r lobed cam, ls6 intake, longtubes, th350 /w 3800 converter, harland sharp rockers.
I show no DTC codes at all, the car idles fine now, changed MAF's to make sure thats not the problem, ive played with everything i can think of in LS1 edit. The a/F curve is PERFECTLY flat at 13.0:1 till it goes straight up vertical off the scale, goes from 26 degrees timing to 5-10 when it hits this spot instantly hits full knock retard etc.. LS1edit scan tool shows everything to be fine up that point, only thing weve noticed is injector's are showing duty cycle is 107-110% (28.8 lb injectors) but the cars not making enough horsepower at this point to run that high (cause the car never gets to stay in it long enough to make any power it seems)
Any ideas are welcome, ive got it strapped to the dyno right now.
When we make a pull (say starting at 3500 rpm) the car pulls hard, a/f right at 13.0:1 a/f ratio, and WHAM right at 5100-5200 rpm the car slams like it hit a rev limiter. When it hits, the a/f instantly goes off the chart lean like it shut off the injectors and the dyno loses the torque reading like it completely cut spark.
If i take the rpms up to 4500 to start, it does the exact same thing but about 5700-5800 rpm...
If i start at 5500 rpm it hits about 6200.
No matter what i do in ls1edit I cant get around it. What could cause the car to be pulling perfect then slam on a rev type "limiter "
We moved all the rev limiters up to 7200 and has no effect.
Car is 408, stock heads, big 238+ xe-r lobed cam, ls6 intake, longtubes, th350 /w 3800 converter, harland sharp rockers.
I show no DTC codes at all, the car idles fine now, changed MAF's to make sure thats not the problem, ive played with everything i can think of in LS1 edit. The a/F curve is PERFECTLY flat at 13.0:1 till it goes straight up vertical off the scale, goes from 26 degrees timing to 5-10 when it hits this spot instantly hits full knock retard etc.. LS1edit scan tool shows everything to be fine up that point, only thing weve noticed is injector's are showing duty cycle is 107-110% (28.8 lb injectors) but the cars not making enough horsepower at this point to run that high (cause the car never gets to stay in it long enough to make any power it seems)
Any ideas are welcome, ive got it strapped to the dyno right now.
09-21-2004, 03:47 PM
#4
09-22-2004, 01:13 PM
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Ive ran the car several times with the same program on the old 346", never had any issues with speed etc. The cars VSS isnt hooked up so it thinks it thinks it is going 0 miles per hour all the time, which is not a problem in anyway.
Car has a 98 ECU for an auto with a painless wiring harness, all smog/evap/tranny codes turned off.
We dont come near the MAF frequency maxing out and even raised it to make sure...
The injectors go 100% duty cycle almost immediately when WOT, but a/f is still really nice. And it goes up to about 120% DC by 5500-6000.... Could the injectors shut themselves down from going static about 2-3 seconds into a pull
Any more ideas? im stumped
Car has a 98 ECU for an auto with a painless wiring harness, all smog/evap/tranny codes turned off.
We dont come near the MAF frequency maxing out and even raised it to make sure...
The injectors go 100% duty cycle almost immediately when WOT, but a/f is still really nice. And it goes up to about 120% DC by 5500-6000.... Could the injectors shut themselves down from going static about 2-3 seconds into a pull
Any more ideas? im stumped
Last edited by C4VetteLS1; 09-22-2004 at 01:22 PM.
