High RPM Problems-UnderDrive Balancer?
04-26-2016, 09:40 PM
#1
High RPM Problems-UnderDrive Balancer? Been fighting high rpm sputtering issues with the new 403 Ls2 motor. In first gear there is no issue but when it shifts to 2nd and gets to 6300rpm or so the car starts breaking up and then the tach dies and goes to zero... But the car is still on and running. I have to turn the car on and off to have the tach work again.
When using nitrous it immediately breaks up and kills the tach and same thing. The car is running but no rpms. Ive found a couple threads with people having the exact same issue caused by the under drive balancer... Im running the Powerbond 25% and wondering if its causing all these headaches...
Yes sparkplugs are fine as are the coils and wires... When data logging there is no fuel cut or afr change when the sputtering starts... Its so weird.
Anyone?
When using nitrous it immediately breaks up and kills the tach and same thing. The car is running but no rpms. Ive found a couple threads with people having the exact same issue caused by the under drive balancer... Im running the Powerbond 25% and wondering if its causing all these headaches...
Yes sparkplugs are fine as are the coils and wires... When data logging there is no fuel cut or afr change when the sputtering starts... Its so weird.
Anyone?
04-28-2016, 07:53 AM
#2
Try adding voltage to your datalog and see if your voltage is holding upper 13 or 14v.
It sounds like you have a problem with the coil harness. Setup your datalogger for misfire and see if you can narrow it down to a specific cylinder(s). I've seen poor connections in the coil harness plug resulting in intermittent dropping out one bank. That was corrected by just re-aligning the connector pins.
It sounds like you have a problem with the coil harness. Setup your datalogger for misfire and see if you can narrow it down to a specific cylinder(s). I've seen poor connections in the coil harness plug resulting in intermittent dropping out one bank. That was corrected by just re-aligning the connector pins.
05-01-2016, 09:43 PM
#3
I'd like to update this thread in case anyone has a similar issue like mine.
It ended up being a bad Crankshaft Position Sensor and not the balancer...
I did a Ls2 403" swap a couple months back and have been chasing this high rpm breakup issue ever since we started tuning... It would only breakup under load in gears 2-3. If i stayed in it during the breakup it would kill the tach but the motor would stay running. It was so frustrating because there were no codes and nothing in the tune looked wrong because fuel pressure, spark, AFR and knock were all spot on or no issues during the process...
From endless searches online i repalced the plugs, coils, and even the balancer for a non underdrive to see if the problem would go away. I ended getting a new crank sensor as a last resort before letting the car sit for a while and sure enough upon doing a WOT 1-3 pull it ran perfect. I then tested the nitrous to see if it would breakup like before and no issues either! So happy this headache is done and can finally dial in the nitrous after all this time.
Thanks
It ended up being a bad Crankshaft Position Sensor and not the balancer...
I did a Ls2 403" swap a couple months back and have been chasing this high rpm breakup issue ever since we started tuning... It would only breakup under load in gears 2-3. If i stayed in it during the breakup it would kill the tach but the motor would stay running. It was so frustrating because there were no codes and nothing in the tune looked wrong because fuel pressure, spark, AFR and knock were all spot on or no issues during the process...
From endless searches online i repalced the plugs, coils, and even the balancer for a non underdrive to see if the problem would go away. I ended getting a new crank sensor as a last resort before letting the car sit for a while and sure enough upon doing a WOT 1-3 pull it ran perfect. I then tested the nitrous to see if it would breakup like before and no issues either! So happy this headache is done and can finally dial in the nitrous after all this time.
Thanks
