I recently helped a friend do a 411 pcm swap on a gen 1 vortec v8 swapped s10 blazer. The issue is that it starts only every other cranking cycle. The vats is on and relinked but it did the exact same thing with the vats off. I don't know where to look to solve this. The truck starts fine the second crank cycle every time so its more of an annoyacne that we want solved.
fuel pressure bleeding off and second cycle fills the rail? Just a thought
1997 Trans Am WS6 - LS1 swap - TR224 - Pacesetter Longtubes - Yank SS3600
- 3.42 Moser 12 bolt - Wilwood Brakes - HP Tuners tuned - P1SC-1 Procharger
Not a fuel pressure problem. It will start and run we turn it off, Crank it with no start release the key recrank then it starts. fuel pressure has been checked during cranking and it is good.
Check your cam position sensor wiring. You might have to swap the outside wires to make it read properly.
I am the owner of the truck in question.
Me and Mike (acehaag) spent about 4 hours tonight trying to trace things down with no positive results so far, although there may be a few things cancelled out now like cam pos. sensor operation and wiring.
What we tried tonight: checked the cam sensor wiring, thought there were a few that were incorrect so we swapped them. It didn't help. I think the 12v reference wire in my blazer is coming from the fusebox, rather than the Red 39 pin on the PCM. The 39 position on my PCM is unused. So then we made a new cam sensor harness out of a spare connector and ran all 3 wires straight to the computer and used pin 39. Same thing, no change.
I think we even tried unplugging the cam sensor and it did the same thing - started every other crank cycle.
A GM Tech 2 scan tool will not allow it to do a CASE learn. Once the truck is running and ready to go it says "vehicle control not allowed".
It's like everything so far is pointing towards a cam/crank sensor problem... but how?
I am very new to HPTuners but have been on here just about every spare minute of my day learning.
In the attached tune and log file, in the table view, you can see the cam sensor seems to be working as far as I can tell. MAF is not plugged in on the current tune in order to check STFT. It is the V6 maf which does not seem to be calibrated right so I have also been working on that.
Reply With Quote