Error Codes P1518 and P1516 under higher boost
Thread Starter
Teching In
Joined: May 2011
Posts: 40
Likes: 1
Error Codes P1518 and P1516 under higher boost I've been trying to sort out an issue for months now and have exhausted my experience along with what I've found searching on the problem. I have a 2004 LQ4 DBW setup on boost and E85. Stock intake and throttle body. It runs flawlessly until about 13lbs at which point it throws a 1518 and 1516. I can't determine if this is a byproduct of the throttle shutting off via some setting I've overlooked and then the boost holding the throttle blade open causes the error code. I can run all day long at 12-13lbs. When it starts to get above this range it throws these codes and enters reduced power mode.
I'm open to any suggestions at this point as I feel my only next option is scrapping the ECM and throttle body or work towards an aftermarket EFI. I'm hoping someone smarter than I am can locate something I've missed in my configuration that is causing a forced throttle close condition under higher boost. I've swapped throttle bodies and installed an LS3 TB with an xlink and same issue. It's strange that it only occurs at higher boost levels.
Specs:
Stock LQ4 with a cam
Stock Truck Intake/100lb injectors/3bar map conversion
Truck DBW TB/LS3 TB with Xlink now
Twin Precision 67/65 Turbos
Stock ECM and modified stock wiring harness
I tested all connections/wiring etc. I also assume that if it were wiring it wouldn't care about the boost level so much and occur all the time.
Like I said I'm hoping I missed something in the torque management or otherwise because I can't make sense of why it would only cause the issue at around 14lbs of boost and up. Ive included a log file of the last run with boost cranked up a bit. When you see the throttle drop it is not me letting off. It shut down, then I got back into it and then it threw a code and shut down into reduced power mode.
Any help would be greatly appreciated as I have already spent months trying to narrow this down. Thank you.
I'm open to any suggestions at this point as I feel my only next option is scrapping the ECM and throttle body or work towards an aftermarket EFI. I'm hoping someone smarter than I am can locate something I've missed in my configuration that is causing a forced throttle close condition under higher boost. I've swapped throttle bodies and installed an LS3 TB with an xlink and same issue. It's strange that it only occurs at higher boost levels.
Specs:
Stock LQ4 with a cam
Stock Truck Intake/100lb injectors/3bar map conversion
Truck DBW TB/LS3 TB with Xlink now
Twin Precision 67/65 Turbos
Stock ECM and modified stock wiring harness
I tested all connections/wiring etc. I also assume that if it were wiring it wouldn't care about the boost level so much and occur all the time.
Like I said I'm hoping I missed something in the torque management or otherwise because I can't make sense of why it would only cause the issue at around 14lbs of boost and up. Ive included a log file of the last run with boost cranked up a bit. When you see the throttle drop it is not me letting off. It shut down, then I got back into it and then it threw a code and shut down into reduced power mode.
Any help would be greatly appreciated as I have already spent months trying to narrow this down. Thank you.
Thread Starter
Teching In
Joined: May 2011
Posts: 40
Likes: 1
The fact that no one jumped in makes me feel a little bit better that I haven't overlooked something stupid and this isn't an easy issue to fix, but I'm trying to break into the 9's in the current set up and I'm so close! (10.0's). If I can fix this then a 9 should be fairly easy. Again, thanks to anyone who can step in and help.
