Haha, yeah the 24 tooth reluctor wheel from EFI Connection only has one way it can go that's is aligned with the keyway, but I'll check it out anyway.
I'm looking for another LS1 harness now that I can strip down to the essentials and make a fuse panel for it.

Because I went through with my build and put the dash and gauges from a 2002 Holden Commodore in, I had to put the BCM in as well and there was no wiring diagram to speak of, so lots of multimeter testing to work out what did what.

I'll make a standalone harness that controls the engine, and then find a wire the required outputs in to the dash harness.

That way I can eliminate BCM/ car circuit interference with the car.

Also with the grounds, I have a 0 gauge ground from the battery to the exhaust header bolt into the heads (about 20" length), as well as a secondary one from the battery to the body, then 2 on the engine harness to the back of each head.

I don't think lack of ground is the issue, but interference of the ground from a positive volt source.

 

Hard to say what your issue is but I would ground the big ground wire to the block somewhere other than the exhaust. Exhaust bolts get really hot and usually rust and may cause a weak connection point. Also a lot of times you have a paper or graphite gasket there (not usually with LS motors) so that's another down side to grounding to the exhaust. All that is besides the fact that your connector/wiring is going to get baked at extremely high temps.



Before you completely re do the harness, I would cut the wires at the distributor and at the computer and run some wiring to each end and try that first. If it works out you know there's a breakdown in that part of the harness somewhere. If it doesn't then you may have to do the whole harness. And actually I would only cut the signal wire and run a new one (not pretty yet or anything just a run of wire) to the pcm and hook it up there. Run a little piece of wire from the battery to the ground and hot at the distributor. In other words I'd do a little verification testing before I ripped everything to pieces.



As far as an oscilloscope, I have a fluke meter I use to test cam and crank sensor signals with, it has the graph at the bottom below the numbers.. the numbers won't fluctuate fast enough to show you your on off signal from the sensor but the graph will react fast and will swipe most of the screen and show you if you're getting a signal from the sensor.

 

Well for $400AUD I can get the entire wiring carcass from an LS1 commodore ute. Engine, body, dash, bcm, and fuse panels.

I'm thinking it would be cheaper and easier to do a complete swap of all harnesses to resolve the issue rather than search 400+ wire ends for my mystery ground.

If after all of this the engine still doesn't fire up, at least I've laid the ground work for a LS1 motor swap and updated my '85 TransAMs 33 year old wiring

 

You need to move that ground to the actual block.

Battery to block.
Block to chassis.
Battery to chassis.

 

I had brand new injectors that caused the same problem. 2 leaked and they dumped too much fuel at idle to fire the cylinder. Had me chasing my tail for a few weeks testing everything else because i never thought the new injectors would be the problem.

 

Yeah I've tried 2 sets of injectors, with no change. I tested the old injectors as well by using a connector with a battery and a syringe to check they held pressure and then opened when they were powered up.

In a mad rush out of the house this morning I put my $20 compression tester on cylinder#1 and cranked the engine for 4 bumps and got a 0 reading which has me worried.

Brand new engine, triple checked all the ring gaps and filed to exact specifications, and diallled the rings 90 degrees of one another as per instructions...
So if its compression that would mean both upper and lower rings had broken to get a flat 0 yes?
My hope is I didn't put the hose on properly, didn't give it enough cranking, or cheap knock off tool doesn't work. The scare is that cyl#1 was the one that always had wet plugs and cold header tubes....

I'll try a few more cylinders this afternoon to eliminate the tool as the issue.

And to address electrical issues, I've bough an entire LS1 wiring loom from a wreckers. PCM, BCM,PIM, engine harness, dash harness, body harness, alternator harness, every wire that is in the car, so it'll be relatively easy to replace the whole wiring system for the car.

 

I apologize if this has been covered/asked already but... was a compression test every performed? Sounds like you've got good fuel/air and spark, compression is the only other thing needed for the motor to run... The fact that it smooths out when you give it throttle seems to point there. Could be that the valves aren't sealing correctly. Would fit with how the motor smooths out when you give it some throttle.

 

It's pointing that way.

No need to apologise, I'd say I've already checked the valve adjustments, and I did, but....


I tried the compression gauge this morning on cyl#1 and got a zero, tried again this afternoon and got the same.
Tried again after backing the valves off half a turn, and then got 100psi on the gauge.
Tried another half turn and still got exactly 100psi.
Tried cyl#3 and got 100psi. Backed the valves off half a turn each and still 100psi.

I'm of the belief the cheap chinese POS gauge i bought is shitty and just registers a max of 100psi not 300.
It also appears to fluctuate rapidly between engine cycles, so i have a feeling the gauge is leaking so 100 is the best it can do.

I'm going to check all the cylinders for 100psi and if i have that I'll feel confident that the gauge is shitty and use it as a 0 or 100 compression/no compression diagnosis.

I know it used to have 210psi compression with a snap-on compression gauge, I'll see if I can borrow it again and test.

 

That happens when you crank and crank on a motor that has no ignition. The injectors are spraying fuel into the cylinders and washing oil off the rings and you'll lose compression. I've seen it so bad that all the oil was contaminated with fuel and the motor wouldn't build compression until an oil change was done. I've actually seen that happen several times, long stories about shitty techs and worn out motors..

First try putting some oil in the cylinder and see if it helps, if compression comes up the rings were washed and you'll likely need to change the oil since it'll have gas in it.

As for you valve adjustments, start with them all on the loose side until you get this running so that you can rule out the valves being adjusted too tight and dropping compression from that. Sounds like you have several issues all at the same time and you need to start knocking them out one by one, adjusting all valves loose for now will at least remove one issue from the table.

The fluctuating in the compression tester sounds a lot like when the schrader valve in them goes bad, you can try a new one from a car/bike valve stem. You'll need to borrow that better tester for sure and confirm that you have at least about 150 psi, hopefully you're closer to 200. But around 100 psi isn't enough compression for the cylinder to fire. From my experience right around 90-100 psi is when a cylinder will not fire at idle. Best I can tell 120-130 is about the lowest compression reading that will still fire.

 

Yeah I'll drop the oil this afternoon. I run an oil analysis lab so I get the benefit of running my oil samples for free
9.5% fuel dilution is never good LOL

I'm hoping there's no damage to the valves and seals if the valves weren't seated properly when the engine was cranking or running, but I guess we'll see soon enough.
I'll loosen all the valves this afternoon and give it an oil change and crank it to see if it fires up, then deal with any lifter noise.

I've already paid for the new wiring, so I'll put that in regardless just to ensure everything is as it should be.

 

That's cool you can check it out at work. Let us know about the oil and how it goes after backing off the valves a little.

If you have to crank the motor with no spark but have fuel unplug the injectors until you get the spark sorted out so you don't wash out the rings. If you have washed out rings it would be helpful if you oiled each cylinder and spun the motor over with the plugs out and injectors disconnected to dry out any fuel and get oil on the cylinder walls again. Then do a compression check from there.

Your valves and seals should be fine.

 

Will do.
I've had the injectors unplugged while I've been diagnosing the spark, but I have a feeling it's all in the valve settings now.
I had 2 of the plugs out, 1 & 3 while cranking to check for valve positions and the spark is VERY strong. It was consistent pattern firing and there was no abnormal sparking. Plus I have the iridium msd plugs so that might help too.

I'll loosen off the remaining valves after work, change the oil, spit a bit of oil down the cylinders and then give a quick compression test on a few cylinders, then try and fire it up.

I was under the impression from everything I've read that the valve adjustment on hydraulic rollers is easier because you can clock them half a turn more after they catch and the hydraulics will pick up the slack/auto-adjust to the right height, but I don't think that was the case with mine.
Anyway, we'll see.

 

Yeah they should. But things don't always do what they should. I would adjust them a little snug but make sure they aren't holding the valves open and dropping compression.

 

Yeah, I'll tighten until I can spin the pushrod and feel it catch and just leave it there for now. If it fixes the issue I'll have a baseline for the vacuum and can adjust on the fly based on noise.
I haven't been able to do it that way yet because the car wouldn't idle on it's own, but once it does I've made a set of valve covers that have the tops cut out so I can adjust them while running without bathing in oil.

 

Love the cut open valve cover thing, and the rest sounds like a good plan

 

DONE!!!!!

 

Awesome and looks like it's running strong!

 

 

I just loosened off the roller rockers until the pushrods could spin in place with no preload and away it went.
I think I was looking for a much more complicated problem when Occam's razor applied.

 

it happens. Glad it was an easy fix! She sounds great!