4.3 Vortec Problems

[Basfis]

Long ago.... I had suburban that gave me fits 3 different times. One was a pinched injector wire. Really struggled under a load.... darn near free fix once found...
another time it stranded me with no fuel and no fire after running poorly.... ended up being a pick up coil....

The last straw was the converter plugging up. Struggled bad under a load.  
 

I got rid of it in 2003, haven’t worked on my vehicle since 😇

[fishinwrench]

16 minutes ago, Basfis said:

another time it stranded me with no fuel and no fire after running poorly.... ended up being a pick up coil....

WTF is a pick up coil ?

[Flysmallie]

3 hours ago, fishinwrench said:

WTF is a pick up coil ?

It's the coil in the distributor. 

[Basfis]

3 hours ago, fishinwrench said:

WTF is a pick up coil ?

It’s a cheap sneaky little POS on the shaft under everything else on a HEI distributor. 

[fishinwrench]

1 hour ago, Flysmallie said:

It's the coil in the distributor. 

Ahh, ok.

[MrGiggles]

What year?

Pre-03 had CSFI with a center spider and poppet injectors for each cylinder. When they get some age, they will start to dribble, or develop vacuum leaks in the intake assemblies. If it goes away at wide open throttle, they are probably dribbling. That CSFI and intake gasket leaks were the achillies heel to those early Vortec motors.

What are the fuel trims like? And does it set any codes other than P0300?

[ollie]

07 Silverado, but basically guts of an 06. Split year on it, but everything under the hood is 06. Haven't checked on fuel trim and yes, that is the only code it shows.

[fishinwrench]

We need a good Auto Mechanic in this place !     

[MrGiggles]

There are a couple TSBs on those 4.3s, one about the A/C line dripping water on it and causing corrosion, and another regarding distributor gear wear. The latter could be eliminated by putting a scanner on it and checking the timing numbers.

I would only look at 02 sensors if it runs good when cold and only acts up once warm. When the engine is cold, it is not even looking at the 02 sensor readings.

A fuel pressure test would be smart as well, just to make sure nothing is leaking down into the intake, although that is usually accompanied with a poor hot start or extended cranking. This also relates to fuel trims, if the fuel pressure was low, you'd also likely have a P0171, and inversely, if it was leaking, likely a P0172.

Where did you get your tune up parts? I got burned by Amazon once, bought a set of plugs that started misfiring within months because they were counterfeit.

That P0300 can be a real bugger to diagnose, since it can have a whole myriad of causes, clogged cats, distributor, crank/cam sensors, ignition failures, mechanical issues, etc. 

[ollie]

I am taking the truck to a mechanic friend of mine on Thursday and we are going to check out a lot of things! He's good and knows his stuff so I am comfortable with him looking into it. He has never burned me and I can trust him so that is a plus. I don't have all the equipment to hook up for those tests and he does. Not so sure about the fuel leaking into the intake since it starts with no problems and normally on the first try. Idles well too. Just can't make a hill with a load on the motor! Doesn't matter how fast I am going up that hill as well. If that motor has to get fuel at a constant amount it just starts to bog down and misfire.