Another one of those threads

[User_name]

Hey guys.
1995 c2500 5.7/nv4500
Running decent at idle, slight surge causing +-200 rpm fluctuations. When im driving at all, it bogs then picks up and goes, bogs then picks back up.
I have code 42 and 52. No I don't have an actual scanner because I used the last of my savings buying books for school.
Timing has been verified at 0* by timing light with the wire behind glovebox unplugged.
Pickup coil in the dist went out. It is new as of a few months ago. It's a delphi unit. So is the coil.
Wires are new. Replaced due to arcing. Plugs are also new.
I really would hate the idea of a brand new dizzy being bad.
What do you guys think?

 

[tayto]

have you verified the voltage at the fuel pump with vehicle running? I would check battery voltage, then the backprobe at the fuel pump. the older C3 ECM has a resistor on the fuel pump monitoring circuit that likes to pop.

 

[User_name]

@ fuel pressure stays at 11-12 psi

 

[tayto]

What about @ WOT underload

 

[Schurkey]

I really would hate the idea of a brand new dizzy being bad.

"New" distributors are generally bottom-feeder Communist Chinese knockoffs. Not unusual for them to have manufacturing defects and low-quality caps 'n' rotors.

I'm not saying yours is giving you problems. But it's suspect until proven otherwise.

Has the timing mark on the damper been proven to line up with "0" on the timing pointer, when #1 is at true TDC?

Drop a bottle of Techron Complete Fuel System Cleaner in the gas tank, see if that cleans the fuel injectors.

Spray aerosol carb or throttle-body cleaner into the throttle body, and the Idle Air passage. See if removing varnish/carbon from the throttle plates/air horn and IAC passage smooths out the idle.

I'm told that throttle body-to-intake manifold gaskets deteriorate and cause idle problems. Those gaskets aren't expensive, but there are several variations--be sure to get the correct one.

The last two times my TBI truck ('88 K1500 5.7L) had unsteady idle, it was the intake gaskets. Kinda suspecting that my intake manifold is warped leading to the gaskets shifting out-of-position.

You really do need access to the data stream via a scan tool.

 

[User_name]

@Schurkey I see your point about the scan tool. With us creeping ever so closer to income tax time I was thinking about getting myself a snapon mt2500 as a birthday present. I will try the cheap stuff first, and if that dosent work I'm going to take it to a reputable mechanic that we've used for a loooonnnggg time. (Don't want to due to tight money, but hey.) This guy started his career at a local chevy, Buick, Olds, and pontiac dealer in the 70s. So he's seen these tbi trucks come and go.
Besides, I'm getting to where I'm trying to stuff too much crap into the little time I have. I just want to be able to at least take it out, stick er on the highway and cruze.