94 blazer stumble/miss

[scotto0609]

Have a 94 blazer unknown mileage or history. Started driving it about 6 months ago no cel and ran pretty well. Light came on about 2 months ago and it indicated it was a o2 sensor so I replaced it same result. The truck runs better when cold,when warm after about 30 seconds it has a miss/ bog on tip in. Any ideas about getting more info out of obd1 or what I should start looking for? Thanks Scott

 

[OR VietVet]

Basics first. Need to have the cat converter checked that may have been the source of the CEL to begin with. What is the fuel pressure? Age of plugs, wires, fuel filter, cap and rotor? Lots of unknowns here.

 

[scotto0609]

No cat,new plugs wires cap rotor O2 sensor exhaust fuel filter and tps. Have new fuel pump on deck.

 

[OR VietVet]

The injector spray should be smooth and in a cone shape. Can check that when running and aim a timing light at the fuel spray. Where is timing set at and what is the spec? Old enough that I forget if you have to unplug something, maybe advance, when checking and setting timing.

 

[exp500]

Was the reluctor inside dist clean or rusty/flaking? I would also look for vacuum leaks and verify or replace MAP sensor. Coolant temp sensors known problem on these too.
When timing engine disconnect wire by brake booster(brown I think) as PNW VietVet recommended. These like 2 degrees more advance for some reason.
And for the O2- add a spacer about 1/2 inch on sensor, slows down response time for setting code.Works about 1/2 of the tries for a $5 fix. Change fuel filter at least yearly. Make sure injector plug wires are twisted.

 

[scotto0609]

Just a small update on this. After using at leas 6 different fuel system cleansers over the last 9 months I put barimans (sic) in it and it cleared up within a day! So as the saying goes: I put that sh~t in everything! Thanks for the suggestions!