Only firing on corner cylinders... 5.3

[bubba68ss]

I have a friend who bought a 5.3 long block from a 'rebuilder' and swapped it into his 01 silverado. He says it is only firing on the corner cylinders (1 8 7 and 2). He swapped everything over from his old engine and is running stock tune, harness, etc. My only thoughts are what if he got a 58 tooth block? Would it even run? Would it fire only half the cylinders? The only way to check is looking at the reluctor wheel right?

[joecar]

If he has the wrong reluctor then it won't run...

yes, pull the CKP sensor and eyeball the reluctor (58x looks uniform, 24x looks irregular and has two rows), or use an oscilloscope to view the waveform.


More likely: check for power to all the coils and injectors, check for PCM signal to all coils and injectors, check compression on all cylinders.

[DocZ28]

Check at the MAP sensor, once and I have missing pulse at 3 injectors only when engine running.

[fatelvis7]

Just something to think about, engine swap motors in my experience , sit for extended periods of time. Injectors tend to plug up when gas goes bad... sticking them closed... just some thing to consider. worth a look