1996 K1500 Engine Swap - Stumbles under Medium Acceleration

[TorchRed77Vette]

First off, just sold my '78 C10 thumpin a 383, and purchased a 1995 K1500 5.7 since I needed something for the bad weather. So new to the forum, and Hello!! But I got a head scratcher for y'all TBI guys.

I bought the Chevy K1500 with a locked up motor and 320K on the body (but in remarkably good shape) for a good price and swapped in a 350 from a 1992 G20 Van. Before the swap I slid in a Summit 1102 "RV Cam", a supposed computer/head compatible cam, and new lifters, replaced the troublesome gaskets/seals and replaced some components due to either missing, for insurance or discovered to be bad:

•Alternator
•Waterpump
•Double roller
•high flow oil pump
•power steering pump
•radiator
•TBI Rebuild

After proper break in of the cam, I set the timing to 0° with the tan wire unplugged, plugged back in, cleared codes. Idles great, take her for a ride; grandma'ing the pedal she accelerates through all the gears fine but as soon as you get the least bit into her she stumbles, misses, and has no power, get out, back to normal. Only threw Code 43 for knock sensor on the test ride....long story short, the van uses the high resistance 100K sensor while the truck runs the 5K, bought correct one. Code gone.

Still stumbles.....Kept my foot in the pedal on the next test drive to see if it would pull through it, but never did and then threw a Code 44, O2 sensor Lean. Thought, must be fuel pressure dropping right?!? Hooked up inline gauge and ran it out the hood as I cranked up and drove normal then laid into it to get to stumble.....Fuel pressure remained steady at 11 psi. It will only throw the lean code if you make it stumble for a long period, driving soft has no codes.

I can see the gas spraying from the injectors with a very nice spray pattern so starting to run out of ideas.

Any Thoughts? Thanks!!!

 

[Big98z71]

Check grounds and for a vacuum leak. Also coil and module

 

[magimerlin]

Time to get the volt meter out.... check the full sweep on the tps...a volt meter with an analog (dial gauge) works best as you can see the fluctuations/bad spots better. Also ohm your ignition coil out and get your ignition module tested.....

 

[TorchRed77Vette]

Yes I had been through all of the sensors that are check able with the voltmeter. But actually figured it out last night. Bad f'n ground at the water neck. Soldered a new ring terminal on and all better. Thanks for the help guys!!

 

[IROCmenace]

Yes I had been through all of the sensors that are check able with the voltmeter. But actually figured it out last night. Bad f'n ground at the water neck. Soldered a new ring terminal on and all better. Thanks for the help guys!!

How were you able to determine that? What does the ground at the water neck go to? I have a miss in o/d under medium throttle right before the trans kicks to a lower gear. TIA

 

[TorchRed77Vette]

There should be like 4 wires (2 eyelets) fastened either under the water neck bolt at the front of the engine or under one of the front bolts for the intake bolt. Make sure they are intact, clean and tight. The wires come out of the same harness that includes the IAC valve and TPS sensor.

 

[IROCmenace]

Thanks, I will check that out.