DIS firing 180 out???

so ive got my old drivabeater back for some repairs. found a whole bunch of attempted repairs that necessetated rewiring the whole damn truck.

truck is a 87 s10, with a 92 blazer chassis wiring harness, 92 lumina 3.1 engine wiring harness and ecm, and 94 camaro 3.4 with DIS and MPFI.

]when i pulled the truck in, it ran. badly, but it ran. hot restart issues, pig rich, lack of power, but running.

now, when i go to start it, it backfires through the TB or muffler. very, very rich. its acting/sounding like its 180 out on the timing. but can it be?

my thought is that the crank poosition sensor is bad. or the polarity is reversed. but i wouldnt think that a low resolution crank sensor would make a difference in polarity, and its wired EXACTLY the way that it has been for the last 4 functional years. still possible its backwards, but highly unlikely. would reversed polarity cause this? or could it be that the crank position sensor was on its way out, and its just coincidental?

any other options i might be missing? ive double checked all my wiring, and the CPS is the only one that has any sort of question in my mind, and the only thing that i can determine would effect timing in this fashion.

it also does it with the injectors disconnected and running on ether, as well as with any of the 3 computers i have for it.

so, throw me a bone here before i tear my damn hair out!

A waste spark engine by definition can not be 180 degrees out.

However, YES if you accidentally de-pin the crank sensor and pin it together backwards, it will run like dog poo if at all. BTDT on a Quad 4 that somebody (cough) knocked the crank sensor wiring out while replacing a starter.

From shaky memory (call it 80% certain): The ignition module reads the falling side of the 6+1 crank wheel. If you get the wires inverted, then it will be interpreting the leading side as the falling, and it will be nearly 60 degrees retarded for a bit, then it gets the reset signal (the 15 degree offset additional tooth) when it isn't expecting it and everything gets thrown out of whack.

I'm not saying that is your problem, but it's definitely something to check out.

Thanks. Turned out it was a bad cps and revedsed polarity.

Fired right up tonight. It wss wonderful.