97 5.0 vortec backfiring through exhaust

[Slimpickens]

Well I'm trying to help a buddy out. His truck just started running like crap. Popping and backfiring through the exhaust.

New dizzy 4 months old
New cap. 4 months old
New rotor 4 months old
New plugs and wires 4 months
New crank sensor 3 months
Fuel psi 60lbs
55lbs running
Inspected spider and all looks fine. No shiney spots from fuel dripping or fuel seepage.
Throwing cam crank correlation code
Showing missfire cylinder 7
Truck has 260k miles all original.
Tested
Maf
Ignition coil... Yes both sides
Ignition control module.
It wasn't throwing the cam/crank
Correlation code until it started running like carp.

Any help is appreciated.
I'm hitting a wall here.
Thanks
Leo

 

[SAATR]

Pull the distributor and check the gear. Good bet that the teeth are heavily worn and causing the CCC code. Replace the gear or the distributor, your call. Another avenue is the cap. They often will start crossfiring between 2 and 7, if memory serves. But that wouldn't explain the P1345, and the knife edged gear would.

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[Slimpickens]

Pull the distributor and check the gear. Good bet that the teeth are heavily worn and causing the CCC code. Replace the gear or the distributor, your call. Another avenue is the cap. They often will start crossfiring between 2 and 7, if memory serves. But that wouldn't explain the P1345, and the knife edged gear would.

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Yeah, I pulled the cap and replaced it with another. Didn't change anything.
To be honest. I worked on this truck about 4 months ago. It just died on him. So he towed it home and I came over and started checking things. Found that the dizzy had just been replaced. So I checked the icm, the coil, the crank sensor... And scratched my head. Ended up the dizzy cap that came with the replacement dizzy had failed internally. I bought a cap. Put it on and boom it fired right up.... Go figure. So I guess I will pull the dizzy and check the gear. Crazy cause it's fairly new, but stranger things have happened....lol
Thank you I'lll try and report back.

 

[SAATR]

Well, when you said all original I figured the distributor was as well, minus the tune up parts. Since it isn't, it's unlikely that the teeth are worn enough to cause your problem. Do you have a scanner capable of running the cam retard offset test, to see how far off it is, and if it's stable? Could be that the distributor moved and started all of this. Though I have seen those distributors pretty far off with no misfire issues. I don't believe in coincidences, so I wouldn't think that you have two unrelated problems here.

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[Slimpickens]

Well, when you said all original I figured the distributor was as well, minus the tune up parts. Since it isn't, it's unlikely that the teeth are worn enough to cause your problem. Do you have a scanner capable of running the cam retard offset test, to see how far off it is, and if it's stable? Could be that the distributor moved and started all of this. Though I have seen those distributors pretty far off with no misfire issues. I don't believe in coincidences, so I wouldn't think that you have two unrelated problems here.

Sent from my XT1585 using Tapatalk

No sir, I do not. I sincerely wish I did. I'm running an elm327 and torque app. I bought it about a year ago just to check dtc's. It will give some live data, but it is not that advanced. I can view the timing advance, but I don't think it's accurate at least on these trucks. I did put it back on tdc to verify that the rotor was pointing at #1 and it was.