Crank No Start

[Schimpfy]

The plugs were one of the first things I checked. They're not fouled fortunately although I do have new plugs that I plan on installing after I get the truck running. I've also checked all of the wires back to the PCM and I don't seem to have any shorts and the voltage is where it's suppose to be.

I replaced the crank sensor early on, but it didn't seem to help anything. Is it normal to get a bad sensor out of the box?

 

[Schimpfy]

After my truck was sitting for over a year I finally broke down and had it towed to a shop for a diagnostic. I figured I had probably overlooked something in the umpteen times I've messed with it and it came down to a really stupid mistake. Lo and behold I was right. I had a broken wire from the crank sensor so I jumpered in new wires to the PCM. I ended up wiring the damn thing backwards. I could not believe I did that especially having a perfect wiring record over an entire Air Force career in aircraft maintenance.

Anyway, truck was running and sounded like crap. Mechanic told me no compression on cylinder #4. Took valve cover off and saw that the exhaust valve was stuck open. Luckily, the piston just has a small point of contact and the valve seat is fine. I'm currently in the process of putting everything back together.

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On a side, yet related, note, is there an easy way to get an EGR valve gasket from between the balancer and the block? Also, there's a post on the rear of the left cylinder head where a couple of grounds are attached but I can't find the nut that was there. Does anyone know the size of that nut?

 

[Schimpfy]

Got everything back together.

It starts.

It runs.

It sounds awful.

I'm getting a P0300 and it falls flat on its face when I give it gas under acceleration. At idle it's fine with an occasional "pop." Using a bluetooth OBD adapter and Torque I've checked and adjusted the CMP offset and it's right around +2 degrees (jumps between +1.8 and +2.1).

I'm going to check the cap. The spark plugs are new, plug wires are new 8mm, ignition coil [not module] is new MSD, ignition control module is new AC Delco. What else should I check?

 

[PlayingWithTBI]

I'm going to check the cap. The spark plugs are new, plug wires are new 8mm, ignition module is new MSD, ignition control module is new AC Delco. What else should I check?

Maybe the ignition coil?

 

[Schimpfy]

Maybe the ignition coil?

Oops, typo in post. I meant to say new MSD coil, not module.

 

[Schurkey]

I'm getting a P0300... ...Using a bluetooth OBD adapter and Torque

Is that system capable of displaying cylinder-specific misfire codes?

Any time I read about P0300, it usually turns out that the scan tool used is lying--the REAL code is a cylinder-specific misfire (P0301--P0308) but the scan tool isn't capable of reporting it, so it displays P0300 instead.

 

[Schimpfy]

The scanner, both Torque and my Actron, have given me cylinder specific misfire codes previously. Now it's just the P0300. I did also get a P0507 last night, but found a jacked up o-ring that was causing a vacuum leak. That problem has been fixed, but the misfire persists.

 

[Schurkey]

Engine put together with fresh plugs, tested-good plug wires, new or inspected cap 'n' rotor?

In my driveway, the ignition coil would be tested for output using a spark-tester calibrated for HEI systems.

If the ignition system is good, that leaves fuel and compression, and an outside possibility of exhaust issues. Most folks aren't set up to verify individual fuel injectors. Fuel pressure under load is about as good as it gets.

I'd be looking into the "Three Sisters" of engine diagnosis--Cranking Compression test, Cylinder Leakdown test, and Power Balance test.

 

[Schimpfy]

Found out that one of the screws (back one) for the cap has stripped the hole in the distributor. As a temporary fix I used a zip tie for troubleshooting. That did help with a noticeable amount of the backfiring and I'm able to use a bit more throttle before I notice the loss of power.

I've also checked the ignition coil with the HEI spark tester. It checked good. Plugs are good...brand new. The plug wires are new, but I'll test them to be sure they're good. They're the Summit Racing ones with good reviews so I ASSumed they were good out of the box.

The fuel pressure is right at 58 psi and I'm using he upgraded spider assembly, although I'm concerned there might be an issue with it.

 

[Schurkey]

Found out that one of the screws (back one) for the cap has stripped the hole in the distributor. As a temporary fix I used a zip tie for troubleshooting. That did help with a noticeable amount of the backfiring and I'm able to use a bit more throttle before I notice the loss of power.

Cap and/or rotor damaged? I'd think that would be very likely.

I've also checked the ignition coil with the HEI spark tester. It checked good. Plugs are good...brand new. The plug wires are new, but I'll test them to be sure they're good. They're the Summit Racing ones with good reviews so I ASSumed they were good out of the box.

I have Summit store-brand plug wires on several vehicles, but they're the ones that get cut-to-length, and then the distributor end terminals are crimped on.

Worth verifying the plug wires.

The fuel pressure is right at 58 psi

1. What is spec?
2. Does the pressure hold under load?

and I'm using he upgraded spider assembly, although I'm concerned there might be an issue with it.

Also worth checking.

Did you ever verify cranking compression, leakdown, and cylinder balance?