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Need help getting my LY6 started with new stand alone harness..

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I'm writing to the group needing some major help. I purchased a four year subscription to HP Academy and have gone through all of the theory up to where I need to start dataloggong and tuning but there's 1 problem... I swapped a Chevy LY6 6L V8 into my BMW X5 and purchased & installed a stand alone wiring harness from Wiring Specialties but I can't get the engine to start now with the new harness. It turns over, it has spark, it has fuel but still won't start. I disabled VATS 1 & 2, DOD has been disabled, VVT has been temporarily disabled but I don't have total travel on my TPS. While recording on the VCM scanner, it flickers from ‪25 - 31‬% without even running and when I put the peddle to the floor, it maxes out at 40%. I was throwing the code P0010 which is a camshaft position sensor so I changed out the original sensor last night with a brand new one and I still have the code coming up.

Also, when I turn the key to 'ON' and the fuel pump charges and it goes through its pre-start checks, the throttle body only twitches a tiny bit instead of making its full range of motion check so I'm thinking there in lies my problem; not enough air.

I need to get it running so I can get a bung welded onto my exhaust pipe so I can install my wideband sensor so I can actually start tuning.

Is there any way you're able to help me?


- How did you verify both spark and fuel?

- What is the fuel pressure reading at the rail?

- Have you tried to spray it with ether (or starting fluid) to see if it kicked?

- The LY6 is a Drive-By-Wire system. I'm assuming you have the throttle pedal attached?

- Is the crank position sensor (CPS) attached correctly? Do you have the correct CPS (should be the gray one)?

Thanks for replying so let me get to your questions now.

1. Through the help of my mechanic buddy, we tested the injectors for power which checked out. We also checked the plugs to ensure there was spark.

2. The X5 is a return fuel system so we plummed in a 99 Corvette fuel filter so the system is now a return system and set the fuel pump to prime for 10seconds. We also checked to make sure we have fuel at the rail. The next step might be plumming in a fuel pressure regulator/gauge, which I have on my car right now.

3. We haven't sprayed ether yet but we did spray gas into the throttle body and it did temporarily sputter to life. It threw a bunch of codes because we manually held the throttle body open to do the test.

4. We have the throttle peddle attached and maybe someone can confirm a question I have regarding the wiring... I got my harness from Wire Specialties and they installed a Cadillac Escalade plug while my gas peddle and motor came from a 3500 Express Van. I was instructed to match the wires colour for colour to attached my gas peddle plug and I did but I hope that didn't somehow screw something up....

5. The CPS was installed securely. I checked that also.

This is something I just found out thou, I has spec'd my harness for VVT and the harness never came with a VVT plug. My whole plan was to be able to tune the VVT to horsepower and fuel economy. I want to be able to make use of the HP this engine can put out but also do a lot of coasting down the highway and hopefully be able to achieve some decent fuel mileage also if it's possible or is this just a pipedream? Davenport Motors here in Calgary does the VVT delete on all of their builds but they're all about making huge power. I plan on adding a cam and maybe valve springs yet while replacing seals and cleaning up the motor but I'm trying to push this motor overly just because it doesn't need to be the quickest SUV on the road. Any input is always appreciated.

If it sputtered to life when you sprayed fuel into the throttle body, this means it's a fueling issue and not an ignition issue. Look at the fuel. You never answered what the fuel pressure at the rail is ... it should be at 58psi (IIRC). If that is good, then your injectors aren't firing as they should. I don't think I'd worry about the VVT as issues with it wouldn't keep it from firing and running. Obviously it won't run as it's supposed to, but it would still run. Fuel is where you need to be looking.

Get the engine running first, then worry about the peripheral stuff.

What about the throtle body not going through its normal cycle though? Also shouldn't it be open on start up?

The fuel pressure at the rail is 61psi.

I sprayed ether into the throttle body on weekend and it tried to start but wouldn't stay running. As I see it I have a couple issues.

1.I don't have proper peddle response and I'm not sure why.

2. My throttle body doesn't go through its full range of motion sequence before I turn the key to start it.

3. Although I have fuel at the fuel rail, something is stopping the fuel from getting into the engine.

Any advice would be helpful in trying to get this thing to run.

Tell us about the wiring and ECU/PCM (what software are you using to access/tune). Is there any chance the Motor+ and Motor- signals (to the DBW Throttle) are reversed?

Can you confirm that you see the Accelerator Pedal Position detected by the ECU (either using scanner software, or ECU calibration software).

For software, I'm using HP Tuners. I went with a stand alone wiring harness to get rid of the BCM.

When I'm running the HP tuners scanner, and the key is to the 'on' position, the throttle position sensor is constantly moving between 25% - 31% and when I push down on the gas peddle, it Maxes out at 40%.

Is there a way I can control or see if my injectors are spraying fuel into my engine because I have pressure (61psi) at the rail.

That does not sounds like the expected behavior of the throttle.

Does HP Tuners show the APP (Accelerator Pedal Position)? The Throttle Position Sensor (TPS) should be the position of the throttle plate in the throttle body.

Sorry I don't have enough experience with HP Tuners to help with diagnostics. Have you checked out the HP Tuners support forum, it seems to be very active, with lots of knowledgeable folks.

As I am quite new to HP Tuners, maybe I should look there instead. I appreciate you trying to help.

As I am quite new to HP Tuners, maybe I should look there instead. I appreciate you trying to help.

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