98 LS swap no start HELP!

[Chase98]

Hello, Im new here and need some help. My ls swap project is my 98 1500, swapped in a cammed LQ9. I followed Brendan step by step on lt1swap to strip both the ls & obs harness and then merge them. Using the obs fuse block and made my own stand alone relay/fuse block to power the LS harness. I took serious time re-working these harnesses and soldering all my connections the right way.
Got everything on the truck, Flashed base tune in, turns over but no start.
My issue is Im only getting spark on #1 spark plug. Non of the others are getting spark. I plugged #1 coil plug into #3 coil and got spark there. Verifying im only getting spark signal to #1 coil plug.
I have checked grounds.
I have replaced crank sensor.
I have checked each ground on each coil plug as well as 12vpwr.
I do notice that no matter where i check for power, once i start cranking it drops down to 10V. But that should still give me spark on all my coils i would think.
I have ohmed out each coil plug signal wire from the pcm pin to the plug and they are checked out fine.

Im all out of ideas, help please. Thanks

 

[MrPink]

fuel pressure?

 

[stutaeng]

Ignition Coil Circuit Wiring Diagram (1999-2002 V8 Chevrolet Silverado, GMC Sierra)

GM 4.8L, 5.3L, 6.0L Index of Articles

easyautodiagnostics.com

What year ECU are you running? I would also check the reference low voltage. Is it 5V?

 

[Chase98]

Ignition Coil Circuit Wiring Diagram (1999-2002 V8 Chevrolet Silverado, GMC Sierra)

GM 4.8L, 5.3L, 6.0L Index of Articles

easyautodiagnostics.com

What year ECU are you running? I would also check the reference low voltage. Is it 5V?

Im not 100% sure of the year but its a 411 with blue/red connectors.
It was previously running my stock 98 5.7 vortec with 4l80e that I swapped in it.
The LQ9 i built was DBW but I switched to DBC. Came out of a 02 escalade.
Do you think this can be a computer issue?

Im not sure on the low reference but i believe its 5V.

 

[stutaeng]

Im not 100% sure of the year but its a 411 with blue/red connectors.
It was previously running my stock 98 5.7 vortec with 4l80e that I swapped in it.
The LQ9 i built was DBW but I switched to DBC. Came out of a 02 escalade.
Do you think this can be a computer issue?

Im not sure on the low reference but i believe its 5V.

Ok, that's good to know. So if it ran before, that rules out things like faulty ignition coils, camshaft position sensor, etc.

I think when you connect the ECU to HP Tuners it gives you the VIN information, no? Yeah, I think Red/Blue is correct for 99-02.

I was asking about the year because the wiring is different between 99-02 and 03 and up. Double check that.

The schematic diagram seems pretty basic. Nothing really challenging there... again double check.

The only other thing would be confirming the integration of the 2 harnesses was done correctly. Again, something to double check.

I'm just a DIY guy and I'm kinda new to the LS platform, so just learning as I go.

 

[Eskimomann209]

My guess check the junction of the coil packs power supply.
The Vortec had one pink wire, where as the LS needed em split to each coil.
I’d also double check into VATS. Make sure it’s deleted.

Lastly if it’s not timing right it could do a similar issue but usually it would fire for a second or so before getting so confused it shut off.
CPS or reluctor ring issue.

 

[Chase98]

Ok, that's good to know. So if it ran before, that rules out things like faulty ignition coils, camshaft position sensor, etc.

I think when you connect the ECU to HP Tuners it gives you the VIN information, no? Yeah, I think Red/Blue is correct for 99-02.

I was asking about the year because the wiring is different between 99-02 and 03 and up. Double check that.

The schematic diagram seems pretty basic. Nothing really challenging there... again double check.

The only other thing would be confirming the integration of the 2 harnesses was done correctly. Again, something to double check.

I'm just a DIY guy and I'm kinda new to the LS platform, so just learning as I go.

Thats right, i followed all of Brendan’s gobys for the 99-02 harness re-work.
Im trying to rule out everything possible before having to pull the harnesses back off. Unfortunately i have them all loomed up and was going on pure confidence smh.

 

[Chase98]

My guess check the junction of the coil packs power supply.
The Vortec had one pink wire, where as the LS needed em split to each coil.
I’d also double check into VATS. Make sure it’s deleted.

Lastly if it’s not timing right it could do a similar issue but usually it would fire for a second or so before getting so confused it shut off.
CPS or reluctor ring issue.

Im getting 12v to each coil plug. I double checked with my tuner about VATS and he said its turned off in the tune. I also just replaced the CPS.
Wouldnt think it would be a reluctor ring issue because i got the motor out of a running escalade. Then just tore it down, bored, and built back up.

 

[Eskimomann209]

Reluctors get pissyif the crank was handled a little rough or if sat down wrong.
They’re usually just pressed on and some slip.
I usually triple check those before putting the crank back in. I do hope it’s not the crank.
Glad everything else checked out ok for you.

 

[Eskimomann209]

Also could you post a link to the process you used on the harness merging. Could help to have one us peek through it real quick.