Kinda perplexed

Hey guys its been a bit since I've been doing its thing. Anyway I'm back to my 96 Chevy z71 k1500 Silverado. This truck has just under 200k. That said its got a reman moter out of a 97 Tahoe with around 5k and a new monster transmission with less than 500 miles. So, I bought the motor after hearing the truck run and seeing all the documentation. Delivered it to the mechanic working on the truck. He did the swap but didn't swap all my new parts over to the new motor. The truck runs and idles great until you put it in gear. Then it starts a slight skip and gets worse when the tranny shifts to 2nd and 3rd. I just swapped all 4 02sensors because before I set this one aside the cel was on and the code was for 02 sensor. Since it was parked in fovor of other projects the battery died and killed the codes. So my question is, what will cause this skip? The wires and plugs along with cap were all swapped. The mechanic said something about a 97 not being the same engine as a 96 so I'm confused. What is missing? What should he have swapped to make this thing right? Or could this be some other crappy issues??
not the same engine? you can look at the castings... BUT
I would suspect the issue would have been seen as a sensor did not hook up, extra wires or a code sets right away,

I think a scanner will be needed - look at live data..


Staff member
There were several different "Chevy 350" engines in that era. Do you have the VIN #s of the vehicle the engine came from, and what it is going into?
Not for the one it came out of. This swap was done back in the spring and I have no way to get in touch with the guy I got it from.


Staff member
Are there any obvious differences? What does the mechanic think is the difference? I'm reading that the different engines weren't related to specific years, but to specific applications. Like, a '97 Corvette would get a different "350/5.7l" than an Express van. I would expect the Tahoe and Silverado would get very similar engines. You indicate the '97 donor engine is a reman, not the original engine even in the donor, so it's getting fuzzier about what you now have.
All the info I have is this. The original engine in my truck is a 350 5.7 was standard in the z71 k1500. The donor was indicated by paperwork to be a GM crate engine, same format 350 5.7 from a 4x4 Tahoe.

Now, after some thinking are the crank reluctors between the 96 and 97 the same? If not would it make a major difference? I am confident the mechanic who did the swap did indeed swap them out but I can't be 100%. I can't ask him because he wrecked his hog on a poker run over the summer and is now pushing up daisies.

I'm simply tossing out ideas, to the point I'm ready to replace parts Willy nilly but we all know that doesn't necessarily fix issues.


Staff member
Yeah, that's a tough question. GM has used "6X", "24X", "58X" (60-2) and even the Optispark derived from a Japanese design. Who knows, maybe even HEI7/8 was still active in those years? This needs further study. For sure, if the reluctor pattern isn't correct for your PCM, it an't gonna work.

If you remove the CKP sensor you should be able to see the reluctor and can count teeth. Do you still have the old engine around to check its count too?
Unfortunately I do not Bill. The guy died before I could pick it up and his wife sold everything that wasn't tools for scrap. I suppose I will have to give my local gm dealership to do some research via vin number to find out what the correct part is. This thing is driving me nuts not to mention the small fortune I've invested in it. So I really don't want to give up on it..
Is this correct -
"The truck runs and idles great until you put it in gear."
It revs freely in Park - and no codes?
So far so ggod - yes no?

Do you have a scanner - able to see live data?


Staff member
I overlooked or forgot the "it runs" part. The reluctor must be correct for the PCM if it runs. +1 on the live-data...

How about the mechanic, is he still around? I'm still curious why he declared it to be a different engine. I'm suspicious of the install that was done, you may need to check the connections of every wire and hose.
Bill, the mechanic died in a motorcycle accident and his widow sold all old auto parts for scrap.

ej1619, have you blocked wheels, set parking brake, moved shift lever into gear so that "Then it starts a slight skip" and then remove plug wires one at a time to try to determine a problem cylinder?
Dan I would suspect your theory - remove plug wire to localize a non performing cyl would be seen by the PCM ie P0304 type codes.... OR in the misfire counts if we really dig deep into mode 6...
BUT I still feel just getting answers to previous posts will help with testing direction.

Can someone help me understand - MONSTER transmission ?


Staff member
Okay, I misunderstood; I thought it was the owner of the donor vehicle that had died. Have the basics been covered yet, like compression, fuel pressure, and some checking of what the spark timing is actually doing?

Dead or not, the mechanic's work still seems suspect to me.