LS Engine won't start

I have not fitted a new cam - engine is as supplied.

It's a little hard to tell from these borescope pictures, but to my uneducated eye, it looks like a 24X reluctor wheel in there . . . (?) Which would be a bit surprising on a new (2 yrs ago), stock crate engine with a grey crankshaft sensor . . . .
 

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I have not fitted a new cam - engine is as supplied.

It's a little hard to tell from these borescope pictures, but to my uneducated eye, it looks like a 24X reluctor wheel in there . . . (?) Which would be a bit surprising on a new (2 yrs ago), stock crate engine with a grey crankshaft sensor . . . .
It looks like it to me too. I think I'm seeing the longer teeth of the 24 wheel. It definitely doesn't look like symmetrical teeth/spaces of the 58.

Could try this but not sure its worth the hassle (from hptuners)

Check if the sensor has 12V (or 5V) at green wire with ignition key open (meassured at the sensor's connector)

Buy a crank sensor connector, plug it to the sensor (installed in the engine). Feed 12V to the green wire.

With a multimeter, set it to DC volts and hook the red lead to blue wire, black lead to ground.
Loose all spark plugs.
With a ratchet on the damper bolt, slowly turn the engine clockwise and watch the multimeter. It should give you pulses of 5V, if you continue to rotate the engine you should see 0V-5V-0V-5V.

Should be able to tell if 24 or 58 by count.
 
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Terry Oxandale

Skinny Man
From post 39 "the sensors each show +4.9v with the correct polarity, which persists while cranking. The signal wires have continuity back to the correct pin on the ECU plug."

Wouldn't this sensor voltage be appropriate for the year of motor, but inconsistent with a 24X reluctor?
 
Some companies (Mast) sell LS7 with 24k for swaps into Gen III cars...but if this was from Jegs/GMPP it seems very unusual that it would have a 24k since I thought this was purely an aftermarket addition. How would they mix up any genIII from genIV?

From post 39 "the sensors each show +4.9v with the correct polarity, which persists while cranking. The signal wires have continuity back to the correct pin on the ECU plug."

Wouldn't this sensor voltage be appropriate for the year of motor, but inconsistent with a 24X reluctor?
I would think that the output of both sensors is on a 5v scale and would not tell you if appropriate reluctor (24x vs 58x), except maybe by counting voltage per engine cycle as in last post. Voltage into sensor is 12v vs 5v but you can usually just tell from the color sensor black vs grey. To clarify though I think three separate variables: correct reluctor, correct sensor, correct voltage/harness. Seems he has correct sensor and harness. Somebody who knows better could confirm.

Maybe I missread though and you are suggesting if it's picking up a signal at all being that it is the 58k sensor then it should be a 58k reluctor. And this may be true. Not sure if a 58k sensor picks up the 24k reluctor signal.
 
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Glad to see that this looks to have finally been diagnosed (assuming there's nothing further!). I'd be wanting a new engine - one that really had been test-run. Hopefully the vendor will do the right thing.
 
Glad to see that this looks to have finally been diagnosed (assuming there's nothing further!). I'd be wanting a new engine - one that really had been test-run. Hopefully the vendor will do the right thing.
+1 on the return. Jegs/Chevy should have better QC!
 
Success!!! :thumbsup:

The engine has started for the first time!

After almost four months, I'm not sure whether to laugh, cry, or just drink a lot of beer. Maybe I'll do all three. . .

The engine arrived back last week. It took a few days to uncrate and reinstall. The spark plugs were removed to crank the engine and build up oil pressure, then the plugs went back in and the video shows the results of the first button push.

And now, for the rest of the story . . .

When I bought the SLC kit, Fran mentioned that a local, reputable engine supplier (Thomson Automotive) had an LS7 for which a customer had paid the deposit, then walked away. If I would be willing to step into the customer's shoes, I could have the engine for a fair price, less the deposit amount already paid. This seemed like a good deal, so we proceeded and when we picked the car up, the engine was already resting on the frame of the car. I paid Fran and Fran paid Thomson.

Fast forward to about 6 weeks ago. We have a new, theoretically stock LS7 crate engine with the wrong crankshaft reluctor wheel and yet the correct crank sensor. In speaking with Brian Thomson, he said that sometimes they would build up an engine for a customer with the old style reluctor wheel, but whenever this is done, they stamp an index number on the side of the engine and keep a permanent record on file of what was done, against this index number. However, the engine in my car had no index number; it had only 6 dots stamped on the side, indicating an unmodified crate engine. In any event, having a mismatched 58-tooth sensor and 24-tooth wheel made no sense at all. This left everyone scratching their heads. Was it an error from GM? Did someone get part way through a modification and then not record it or stamp it and then put the wrong sensor on it? All Fran did was pass along the engine and place it in the frame. After 2 years since purchase, GM would not honor a warranty and without any clear evidence of where things came off the rails, it would be pretty hard to make a case.

To make a long story short, Fran offered the use of his corporate shipping rate, I paid the shipping and at no charge, Brian Thomson stripped the engine down and rebuilt it with all of the necessary, stock LS7 components.

Both Fran and Brian were helpful, responsive and accommodating.

While there are still some unanswered questions about how my engine wound up in the state it did, I am happy that it is now installed, running and the SLC project is back on track.

Here's a link to the video evidence: https://youtu.be/H89Rz09pLb0
 
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Thanks!

I tried uploading several different video formats and all either weren't allowed formats, or failed with an error message about a missing security token. I have edited the post with a Youtube link that will hopefully work . ..
 

Keith

Moderator
What a saga!..and well done for being the epitome of patience throughout it all :thumbsup:

A bit worrying to learn you were not protected by any warranty and I suppose it begs the question: was the amount of premium the price was reduced by eventually worth all the grief? If the price reduction was significant I suppose yes, but otherwise?......
 

Howard Jones

Supporter
Sorry to hear of your uncomfortable situation but the good news is everybody involved acted honorably and in the end it didn't turn into a huge loss of money. Things like this end up much worse more often that not with lessor people.

Congrats to you all.
 
Wow! Finally. Now you can get on with the rest of the build!

What kind of mufflers did you use? they were doing their job...
 
Wow! Finally. Now you can get on with the rest of the build!

What kind of mufflers did you use? they were doing their job...
FlowMaster DBX 6" mufflers Flowmaster Hushpower DBX Mufflers 13014310 - Free Shipping on Orders Over $99 at Summit Racing

The rod ends had to be modified a bit to fit them in - and even then, it's pretty tight. Might have some issues with movement and resulting vibration from the rod ends contacting the muffler, but we'll see. I wanted something that would breathe well but not wake up all the neighbors every time it drives down the front street. They're noticeably louder than the Corvette at idle, but not obnoxiously so.
 
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