Needing some help getting the LS2 started

[Riggs 74]

I am just about done with an LS swap into a 74 Corvette, I am having problems with getting it to fire though. I have fuel pressure at the rails, voltage at the coils, but no signals at the coils or injectors. The ECU has had the VATS removed and the harness was reworked buy Current Performance.

What I am I missing? The car turns over but has no sign of firing.
The motor and trans are from a 2008 SS Trail Blazer.


Thanks for any one that can lead me into the right direction.


Riggs.

[FatfreeGTO]

You are probably losing your 12v during cranking to your ignition feed.

[Riggs 74]

I was, with the way I had it wire before, the ignition would lose power as I was cranking the motor, but I have since wired that to stay hot with key on, and while cranking. I now have 12v at the coil while cranking, but no ecu signal.

I'm thinking it's the crank sensor. What should my readings be at the crank sensor and at the pig tale?


Riggs

[FatfreeGTO]

Sorry but I don't know that info. Hopefully someone else has more insight.

[Trevor @ Texas Speed]

If you have a crank or cam sensor issue, it will initially try to fire and then die most of the time. It will also throw codes for both of these issues. Do you have the correct gas pedal plugged in? If you don't have the correct pedal plugged in it won't start! I know because I went through this on my '67 Chevelle with the LS3 swap. :)

Check the pedal and let me know. Feel free to shoot me an email at [email protected].

Trevor
Texas Speed & Performance

[Riggs 74]

I would Guess I have the correct pedal assembly, I had Current Performance rework the harness and add in a Accelerator pedal with pig tail. I asked them several times if it was a problem to complete, and they said no, all they needed was the make, model and year of vehicle the harness and ECU were from to be sure they had the right assembly.

So if the Crank sensor is not functioning the car will still try to fire?

I have sent my tuner a question regarding the removal of the VATS to be sure he did complete that before sending it back to me. I had the ECU and TCU reprogrammed for a base tune by http://tunedbyfrost.com/.


Riggs

[garys 68]

Vats only disables the fuel pump after initial start.
No codes?

[tooblue]

You may want to make sure you have the coils on the correct side. Not sure on LS2s but I am guessing they have that same potential to mix up the left/right sides. Roger

[Trevor @ Texas Speed]

Yes, even with a crank position code it will still try to fire. Our '05 twin turbo Corvette that we built back in 2005 had a crank code, and it would start, sputter, and then die. I would read the part number off of the pedal assembly and cross-reference it to make 100% sure that it is the correct one.

[daytonayellaz]

Hey Terry.... Sounds like a programing issue. Give me a call and we can try and walk through it over the phone. Nice to see your so close:cheers:

[12sec ss]

On my swap one wire was broken going to the crank sensor, and it would not fire or throw codes. Easy way to chech is to see if you are getting RPM reading on the tach while cranking. If you are not, then its a crank sensor issue

[Riggs 74]

Hey Guys, not sure how I missed your post, but I just found them this morning.

When I try to check for codes with a pocket scanner, the results come back as FAIL, What the hell is that? Programing or wiring? What sucks is, I had professional shops take care of my wiring needs and my program needs, so I would hope these area's are fine.

What type of scanner could I buy to show me live engine data? The one I have will not do that. I am thinking about HP tuners, but I wasn't sure I wanted to spend that much on a system, or have time to learn the program right now..
Any thoughts?

Trevor, What would I check for on the pedal? Pin count and location of pins? I will check for a part number and try to cross reference to be sure that the pedal is correct.

Gary, I'm not sure if the vats are on or off, the fuel pump comes on and builds pressure when you first turn the key on, then I believe I am hearing the relay opening and closing each time I try to start the car.

Tooblue, I'm not sure how the coil packs being flopped would change anything, good or bad. The coil packs are the same part numbers, unless the harness there at the coil pack would be the issue, being on the wrong side, I'll look into it.

Travis, Good to hear from you, I hope all is well with you and your family. I don't have any way to read/look at the computer program Yet, once I get into that, I my end up giving you a call.


12sec SS, I will have to put the Gauges back into the car and see if I get any signal at the tach while cranking.

I appreciate you guys helping me with the start of the LS, hopefully soon we will figure it out.


Riggs

[garys 68]

Not sure what "Fail" means, you might want to check the manual that came with the scanner.
If you just want to get real time sensor data and codes, get one of these.
http://www.ebay.com/itm/ELMScan-5-Universal-OBD-II-Scan-Tool-w-Free-Software-/200519139829?pt=Motors_Automotive_Tools&hash=item2eafdf41f5&vxp=mtr

[Riggs 74]

Damn Gary, nice find. I thought I was going to have to spend a couple of hundred on a live scanner.

Thank.
Riggs