98 5.7 120,000 miles code p0308

[Oldscratch]

Little help please! On a trip, truck ran great, parked it. Started it the day after to move, idle rough. Ran like crap. Freeze frame data with crappy code reader attached. I’m not super proficient with reading fuel trim data. But can anyone chime in on what to tackle first ? I’m about to go to the store and get. Plugs. Wires. Coil. Fuel filter. Etc. any help would be appreciated thanks.

 

[b454rat]

Simplest would be to change plugs n wires....

 

[Oldscratch]

Simplest would be to change plugs n wires....

Thanks. That’s what I’m going to start with. Cheers

 

[1997]

My 97 had same symptom, ran great, next day start p0300 code.
turned out to be a poppet in the spider assembly not working.
replaced with the new style, so far so good.

 

[Oldscratch]

My 97 had same symptom, ran great, next day start p0300 code.
turned out to be a poppet in the spider assembly not working.
replaced with the new style, so far so good.

That’s the way I’m leaning after basic tuneup stuff. Luckily my friend had a car for me to borrow. Going back thurs with the spider. Thanks for the reply. Good luck

 

[Schurkey]

Plugs. Wires. Coil. Fuel filter. Etc. any help would be appreciated thanks.

You have a problem with Cylinder 8. Cylinders 1--7 are OK.

Stop looking at parts that affect all eight cylinders. It's not the coil, and it's not the fuel filter.

In this case, it's something that affects only #8--plug, plug wire, distributor cap, injector, intake gasket at the #8 port, etc.

I'm not saying a comprehensive tune-up is a bad idea--although "new" ignition coils are almost certainly LESS good than the OEM coil in there now; and I've heard horror stories about cheap caps and rotors on Vortec distributors.

For that matter, I've heard horror stories about Vortec distributors.

 

[Oldscratch]

You have a problem with Cylinder 8. Cylinders 1--7 are OK.

Stop looking at parts that affect all eight cylinders. It's not the coil, and it's not the fuel filter.

In this case, it's something that affects only #8--plug, plug wire, distributor cap, injector, intake gasket at the #8 port, etc.

I'm not saying a comprehensive tune-up is a bad idea--although "new" ignition coils are almost certainly LESS good than the OEM coil in there now; and I've heard horror stories about cheap caps and rotors on Vortec distributors.

For that matter, I've heard horror stories about Vortec distributors.

A tuneup was due anyways yes. So I kinda just did it to rule out the plug wires. Or plug. When I go back I’m taking a dis cap. And the injection spider. To be ready. Thanks for the reply.

 

[Mr Eric]

I had a similar event several years ago.
Ran fine, parked it for 14 hours ( overnight) and no start.
Trouble shot to the cap and rotor. It was near the ocean, the same air, moisture and a cheap cap had eroded/corroded the internal terminals in just a couple of months. Still never figured out how that much moisture was getting in. Perhaps it was from not driving it very far each day, and but getting hit enough to bake or all the moisture, but enough to cause a draw cycle.

No matter the cause, now I carry a spare cap and rotor to the rest of my spare and parts kit.