HP EFI CNP upgrade

10sec.et · Posted: Fri Jun 29, 2018 12:28 am Post subject:

I'm a little lost here. Are you still having weird electrical issues?

Paul P · Posted: Tue Jul 31, 2018 7:53 am Post subject:

Installed the NTK and it pulled a ton of fuel out of the tune. Running like Shocked

Still had some EMI issues. TPS was changing to almost 8% idling at 2500 rpm at points just sitting there. Since I had done all the work on the + side with isolation moving wires away from noisy sources I took some chokes and installed them on every ground as it left the block. I put each at the point where it entered the wiring harness. 2 coil pack grounds some other grounds for the computer and nitrous solenoid. Amazingly that did the trick. I have log pictures of the before and after and the traces were really noisy before and almost flat after. Car starts very quickly now too since there is a clean signal to the ECU. All I can say is AMEN TO THAT!!! Hope everyone is enjoying their summer. I did attend the nationals at Epping again. It was great.

Paul

Paul P · Posted: Mon Aug 27, 2018 10:49 am Post subject:

I think I found the origin of my issue. The harness!!!! WTF??? HP EFI Harness has an open common ground for all the sensors. If I wiggle the junction for the TPS, CTS, MAT and IAC cables they all go max open circuit voltage. All the sensors are ground chained together to pin A18 on the ECU. The junction must be junk from Holley as I have been fighting this for over a year. The sensors numbers when this goes bad from a wiggle with the ECU powered up and the software linked (car not running) are:
TPS 100%
IAC 98%
CTS -15F
MAT -16F
Oil pressure 108psi
Fuel pressure 106psi
Of course I won't get any help from Holley on this since the warranty has expired. Still sucks since the harness was not something I would have thought was a problem.

Paul P · Posted: Tue Sep 04, 2018 10:01 pm Post subject:

Update on the harness. I called Holley tech support and explained my situation.Sent a video of the sensors all going high and it looks like I will be getting a new one. Support tech said not only was it dangerous but shouldn't happen. Holley will stand behind the harness issue and send a replacement. He did say he hadn't seen it before which I take with a grain of salt since I can't be sure about the real numbers. Still good news. It arrived at Holley in Bowling Green, KY today so hopefully there will be a harness in my hands by the weekend.

Paul P · Posted: Tue Sep 18, 2018 3:47 pm Post subject:

Harness has been replaced and it starts up and runs without any gremlins. At least the front of the car is ok now. LOL. Rear is a different story. Rolling Eyes