Engine misses under load

[konstan]

Ok at least i know what my condition is called. My truck's condition, that is.

It is missing, and only if under load. The best way to demonstrate, so far, has been

- put parking brake on
- turn on truck
- put truck in 'D' (or 'R' or whatever gear)
- tap gas sharply

i can actually get it to die this way.

So, its missing. So far i did the following (while doing other work on the truck)

- intake gaskets
- valve cover gaskets
- cleaned IAC motor
- spark plugs & wires
- cleaned injectors (while i had the manifold off)
- tomorrow gonna change the fuel filter. Not anticipating a difference b/c i can rev it in idle all day long, but still, need to eliminate.

 

[MrShorty]

Any codes in the computer? it only takes a few minutes, even if there isn't any information there.

I would go ahead and change the fuel filter, probably even put a fuel pressure gauge on it to see if fuel delivery is keeping up with engine demand.

Double check the plugs and wires (maybe at night with a spray bottle of water). Just to be absolutely sure there's no spark leak under load.

Vacuum leaks?

 

[konstan]

Any codes in the computer? it only takes a few minutes, even if there isn't any information there.
I would go ahead and change the fuel filter, probably even put a fuel pressure gauge on it to see if fuel delivery is keeping up with engine demand.
Double check the plugs and wires (maybe at night with a spray bottle of water). Just to be absolutely sure there's no spark leak under load.
Vacuum leaks?

Codes: no; though I should probably check again, just for good measure. Two days ago I checked and it was just 111.

Vacuum leaks: no. Sprayed carb cleaner around the intake and around the engine bay to check. There is vacuum in the system hours after the engine is shut off, so, good.

Tonight going to do the fuel filter and pressure gauge thing. Gotta get the tool to disconnect the filter -- previous owner got those aftermarket lines with no clamps, can't do them with just a screwdriver

 

[konstan]

update

New fuel filter; still misfires about the same.

Wasn't able to borrow a fuel pressure gauge, but will do that soon.

How can I get to the O2 sensor connectors? I can't reach them from underneath or from the top... they are way in there???

 

[MrShorty]

My '92 only has one sensor, but I find that coming through the wheel well gets me the best access (still not great) to the rear O2 sensor connector.

 

[konstan]

You guys aren't gonna believe this, but...

I had two of the spark plug wires going to the wrong terminal on the coil.