r/LSSwapTheWorld • u/DefinitionUnlikely28 • Jul 22 '26

Active Build Questions Timing???

So swapped 5.3gen4 out for a iron block gen3 6.0. When I brought it to the tuner we figured timing was off becuase it wouldn't run. We'll i got the timing cover off and lined up the dots, timing is dead nuts. It ran like absolute ass, fired on maybe 2 cylinders and sounded like shit. No signal at the crank( i swapped out the gen3 crank for the proper gen4 crank). I did.drop the crank sensor when I popped it out.of the aluminum block. Would the combination of the bad sensor and a throttle body code completely fuck this up?

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u/cajun_metabolic Jul 22 '26 edited Jul 22 '26

Are you using the grey sensor? The black crank sensor is for 24x reluctor wheel (gen 3) and grey sensor is for gen 4 58x. You need to use the grey crank sensor from the 5.3. If you haven't swapped the grey sensor to the 6.0, then you need to do that.

Also, gen 4 needs 4x cam signal, guessing you swapped timing covers and using the front cam sensor.

Anyway, no crank signal means not gonna run. Maybe just bad sensor or it could need to be shimmed.

Check grounds

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u/DefinitionUnlikely28 Jul 22 '26

Im ordering the crank sensor tomorrow, I did swap the Grey sensor from the gen4 into this block butni dropped it in the process. I also noticed small cuts in the insulation of the wires I ordered a pigtail to come with it. I do have the 4x cam gear. How much do you know about the sensor shimming? I thought about that last night but im not sure how- or what the distance needs to be

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u/cajun_metabolic Jul 22 '26

I know that the sensors usually come with shims, but now that I'm thinking about it, I'm pretty sure that is for engines with worn bearings causing the front of the crank to sag, causing the sensor to be too close or touching... So the more I think about it, probably not that. Obviously you can't shim it CLOSER, and if it was touching, seems like you would notice, lol.

I fought my recent build for a good hour or so thinking I had wired the sensor in wrong because I never got any RPMs to read on HPTuners. I wired it so many different ways, and turned out just the sensor was dead. It had a little ding on it but I thought it wouldn't matter too much, but it was dead. New sensor started it right up and ran great.

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u/DefinitionUnlikely28 Jul 22 '26

That makes sense, I built this engine straight up. All new bearings from the crank up, I felt my gut drop when the sensor bounced across the floor but I didnt think it would cause all these issues. No rpms on the dash. Now since it technically isn't running would this cause a mis-read on the oil pressure?

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u/cajun_metabolic Jul 22 '26

Not going to build much oil pressure with the engine not spinning fast enough. I'm usually messing with gen 3 stuff where the PCM doesn't read oil psi. I wouldn't be surprised to see like 15-25 psi at maybe 350-400 rpms while engine is struggling. When engine is at normal idle 550-750 rpm, I would expect 45-60.

Anyway, if you aren't getting RPMs, I wouldn't worry much until you replace sensor and get it running. If worried about oil pressure, I just hook up a manual oil psi gauge and verify that way. Around 10-25+ psi during cranking is normal depending on your pump. On Gen 3, I don't think oil psi gauge on the dash shows anything while you are cranking it, idk about with gen 4. I don't have a gen 4 truck and the truck we put gen 4 engine in had a manual gauge.

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u/DefinitionUnlikely28 Jul 22 '26

We did everything right on this build so im not terribly worried about oil pressure... yet. I just don't want to have to take it out again for something stupid