Can't rule out anything yet! Incorrect camshaft retard could easily cause what you're experiencing. Clear the DTC's with a scan tool. Perform the General Motors Driving Cycle After the drive cycle, check monitor status on the scan tool, make sure all monitors are complete. If not, do the drive cycle again, all monitors must be complete. Need to follow the instructions exactly as written, or the monitors will not complete. If the SES light comes on, check freeze frame data and post it.

If you can get your hands on a scan tool overnight, there are some tests that can be done with the engine stone cold. The tests are done after the vehicle has been off for 10-12 hours, BEFORE you start it. Need to make sure IAT, ECT and ambient temperature are all with 1 or 2 degrees of each other.

 

Update:

Got a little more specificity to my issue. At part throttle, it shifts fine and strong. It's only at half or WOT that it jumps during 1-2 shift. All other shifts seem fine.

I'm still working on getting a capable scan tool but it's not looking like it will be soon. Probably sometime next week. I also plan on getting the camshaft retard adjusted after the transmission fluid change later in the week. Crossing fingers.

 

What were the numbers on the fuel pressure and leakdown test? If it acts up only on medium to heavy crowd, it might be a problem with fuel delivery. Did you check the fuel filter for restriction?

 

Leak down was 60 to 56 aftrr ten minutes. Changed tranny fluid though and took a look at the accumulator piston.


Piston was fine but the sping was in three pieces. Put a new piston and spring and fixed the shifting issue. Seems I got so used to how it shifts that I didnt even notice the gear change!

Plan on getting can adjustment done tomorrow to het my hp back. Is there anything else I should check? It is important that cover everything.

 

Sounds good, keep us posted on the results.

 

Quick question:

I was told by a mechanic that due to my distributor being non-adjustable, I wouldn't need the cam adjustment as the static bolt doesn't allow manual adjustment.

Is the process auto-learning or does it indeed require me to adjust the distributor while I'm looking at live data?

 

Ahh, but the distributor IS adjustable. The base of the distributor, where it goes through the lower intake manifold, is slightly smaller than the hole in the intake manifold. When you loosen the distributor hold down bolt, the "slop" allows the distributor to rotate slightly, on an arc. Total adjustment is only ~15 degrees, (~7.5 degrees in each direction). The measurement is NOT degrees of distributor rotation. The live streaming data is viewed on the scan tool as camshaft retard degrees. In other words, the distributor will not physically rotate 15 degrees, but camshaft retard degrees will change. If camshaft retard will not come into spec, the original hold down bracket must be removed, modified, and reinstalled, or removed and replaced with an old style small block chev distributor hold down bracket, (Mr. Gasket #1009, ~$5). This will make the distributor fully adjustable to get camshaft retard within spec, (zero degrees plus or minus 2 degrees).

NOTE: Rotating the distributor on this engine does NOT affect ignition timing. Ignition pulse is generated by the crankshaft position sensor, not in the distributor. When camshaft retard is set correctly: If you disconnect the camshaft position sensor, the check engine light will come on, and cylinder misfire detection will be disabled, but the engine will start and run the same as when it's connected.