'96 C1500 4.3/4L60E - Misfire after Trans Swap

[AboveTheLogic]

Oh that makes sense! Thank you.

 

[Schurkey]

That's the important difference between a "lean condition" and a lean sensor signal.

 

[AboveTheLogic]

Replaced the distributor cap and rotor, plugs, and wires.

Fired up, ran smooth at idle. After a few minutes, rough running returned.

I didn't expect that to fix it, but I was hoping. Now I need to really fix it and limit test drives to not foul my new plugs.

I picked up a cheap smoke tester to check for leaks. Fuel injector testing kit coming later in the week.

I think I left out an important point - the left turn signal light is on...sometimes. The left headlight sometimes works. This was a problem before I pulled the trans, before the misfire got this severe. The last 2 test drives, I noticed a burning smell. Just a few minutes ago I noticed one or two of the wires going to the starter were making contact with the passenger side exhaust manifold, so I pushed them down.

Next steps....

-Smoke test for leaks.
-Follow FSM steps to check for electrical shorts at the O2 sensor.
-Injector balance test.
-Locate, inspect, and if necessary, replace ground straps. I don't know where they all are and will look for a diagram. If there is supposed to be one at the starter, that may be my problem.

 

[AboveTheLogic]

Lots of smoke coming from right here during the smoke test. I put that upper clamp on thinking it would help, nope.

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[AboveTheLogic]

Update.

Replaced this hose. The PCV hoses at the auto parts stores are totally wrong. Way too small. I found this universal 90 degree 3/4” host on Amazon and cut it down.

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After replacing that, I ran another smoke test. Some small amounts of smoke seeping out of the large flexible hose to the right there, by the clamp, and at the spot where the big plenum to the left in the photo connects to the piece that sits on the throttle body.

The seepage was minimal and only after a few minutes of pressure so I snugged down those large hose clamps and moved on. I’m guessing that’s normal.

Went on a test drive. Within 1-2 miles of driving it threw another P0151 code and stumbled under moderate throttle acceleration at low speeds (25-30mph) and low RPM. Engine would have been around 170-180 degrees then.

After some more driving, it warmed up fully and ran a lot better. Lots more low end torque. Monitoring the sensor voltage, Bank 2 Sensor 1 is still very low. In the 0.10 range under light throttle when Bank 1 Sensor 1 is closer to .80-.90.

The passenger side is still running very lean under most conditions and the low end torque is suffering.

I did a full throttle run in 2nd gear and heard some knocking up in the 5,000 rpm range before the trans shifted to 3rd. Another sign of lean conditions. Won’t do that again until it’s fixed.

It’s diving pretty good when warm, but more work to do. Far from perfect.

I’m very interested in the results of the balance test.

 

[Erik the Awful]

Have we said to go check all your grounds yet?

 

[AboveTheLogic]

I have not yet. Definitely on my list. Would like to find a diagram or list of all the ground strap locations.