s484 418 spark
04-20-2016, 04:37 PM
#1
s484 418 spark Got a lsx 418 with a t6 s484 with 1.32 housing and 96 turbine. This setup is in a truck, and trapped 138 mph on 14 psi and 17 degrees of ignition timing on the top end. It's on e85, cr is 9.5:1 . The issue is the truck experiences spark blow out only on 4th gear on a 4l80e. The boost controller also doesn't want to go higher than 14 psi. I suspect this could be a back pressure issue? Plugs are br7ef gapped at .020". Afr is 11s on a gas scale. Or .78ish lambda.
Coils are relocated and is running standard length coil wires. Running round coils with the heat sink in Em. Don't want to close the gap even more as I suspect the issue is somewhere else. Going to change the coils tomorrow, and try cleaning the injectors as well. Plugs come out clean btw.
Reason why I think it could be back pressure is due to the fact that the boost controller can't give any more boost at 100% duty cycle which is assume the bp is forcing the gate open. And the excess back pressure is at its max on 4th gear which blows out the spark.
Any theories or ideas guys? Plan on putting a boost gauge on the dp to check boost to back pressure ratio. The turbo was recommended by ljms.
Coils are relocated and is running standard length coil wires. Running round coils with the heat sink in Em. Don't want to close the gap even more as I suspect the issue is somewhere else. Going to change the coils tomorrow, and try cleaning the injectors as well. Plugs come out clean btw.
Reason why I think it could be back pressure is due to the fact that the boost controller can't give any more boost at 100% duty cycle which is assume the bp is forcing the gate open. And the excess back pressure is at its max on 4th gear which blows out the spark.
Any theories or ideas guys? Plan on putting a boost gauge on the dp to check boost to back pressure ratio. The turbo was recommended by ljms.
04-21-2016, 01:17 AM
#5
its on a 15 pound spring i believe. theyre 2 gates. and MSD wires.
dont have an EGT probe, but the manifold glows pretty red during WOT pulls its those cheap front facing exhaust manifolds. Hence another reason why i think theres backpressure issues. AFR 11.5ish, timing at 17* on 14# on e85.
dont have an EGT probe, but the manifold glows pretty red during WOT pulls its those cheap front facing exhaust manifolds. Hence another reason why i think theres backpressure issues. AFR 11.5ish, timing at 17* on 14# on e85.
04-21-2016, 09:35 AM
#6
Theres been a lot of horror stories about msd wires either ohm them out or try changing them and see what happens also if your manifolds are glowing red you could be running lean but i would start with the wires and go from there