95 silverado TBI diagnostics: im stumped

[dusterbd13]

Truck is a 1995 c1500. 5.7 TBI, recent4l80e swap using BJDR bin burned onto a memcal using the moatessoftware and prom adapter. Stock everything else with 166k on it.


Since ove pwned the truck (9 months orso) its been dead nuts reliable. Until the 4l60e died.


The 4l80e swap was uneventful. 1000miles since the swap. While we were in asheville, started acting up.Would kick the check engine light (paperclip trick only showed onelong flash), and shift hard. Shifted extremely late 1-2, and it actedlike first was slipping (not pulling in first like it normally does.Like converter was a really loose one suddenly). Would go away aftera key cycle, and go back to normal. Couldn't figure out a reason forit, or a precursor to the CEL and behavior that seemed to beconsistent. I guessed that the TPS was the culprit, and put tunerproon it. Noted consistent and linear TPS readings from the computerend. So I replaced the connector, as it was pretty crusty looking andno longer had the weather seal on it. This was done after the firstinstance of the CEL and shifting, before asheville. Happened threetimes after replacement of the connector.


Yesterday, after fixing the airconditioning, and extended idle times, things got worse/weird. NoCEL, second gear only, idle at 2000rpm.i shut it off, hoping thetrick that we learned in the mountains would fit it again. verydifficult restart. As in, extended crank times, no start. Finallydid, and got it home. Hooked up tunerpro, and other than noting IACorder being at 90, and TPS voltage being high, nothing odd in thedata and no codes set. Tried unhooking the TPS and no change.


Today, we tried to start it to moveit. No start. Noted that there was no prime pulse form the injectors.However, fired right up on ether and revved good. Got it moved,second gear only other than reverse. So I know we have spark, andfuel when its running. Tried swapping ECM with another (reusing myburned chip setup) with same results.


Got no idea here, and don't want tostart shotgunning parts at it. Has to be something im not thinkingof.


Far as diagnostics go, Im not even surewhere to start, as there's no codes or obviously strange data to leadme in any particular direction.


What diagnostics/where to start?

[ScottP]

One of my favorite expressions when diagnosing problems like these is "It always stinks worst
where you S**t last".

I'd be looking in the vicinity of the PCM and the memcal. Did the memcal get seated properly
in the PCM after the new calibration was burned? All of the PCM connectors seated properly
if the PCM was removed as part of the update?

Was it the original EPROM that was UV erased and reprogrammed with the BJDR image? If so,
did it verify properly after? Erasing 25+ year old EPROMs doesn't always go as well as we'd like.
The old 2732's tended to be the worst as far as failing to erase and program, but I've also seen
a handful of 27C128 and 27C256 devices that wouldn't erase fully or program properly.

Good luck!

-Scott