Hi,
I have been pulling my hair out for the past few months trying to figure out why i have a stumbling intermittent miss that gets worse the longer the car runs. I finally took it somewhere, and after 2 days, of going over the car, and a $150 "troubleshooting" bill, they determined that 3 of my fuel injector wires were stretched to the point of making intermittent contact.

To save the $20 a piece cost for fuel injector pigtails from the dealer, I found a Harness from a 94 baby-LT1(4.3Liter) Impala at the Daytona U-Pull-It junk yard for $18. After splicing almost all of the wires in, matching the color of my existing wires to the color of the wires on the impala harness, I noticed that the wire colors on the fuel injector connectors on the Impala harness were reversed from my existing connectors. I started the car up and it runs like crap, and wants to die, with the idle going all over the place. What effect would these being reversed have on things?

I'm suprised it would run at all, you're spraying fuel on top of the intake valves at the wrong time...the valves could be closed and you're setting yourself up for a big back fire! The stock LT1 harness has the cylinder numbers printed on the injector harness connectors.

Yes, they were printed on the impala's LT1 also, but the wire colors were reversed. And actually, even with some of the wires reversed, I drove it around for a few minutes, and it runs exactly like it did before. Are you sure it would be dumping fuel at the wrong times? I got no SES light....and when i though the car was running even worse, it was because i had unhooked the brake booster line. After I re-connected it, it ran like it did before.

now by reversed what do you mean...exactly..........

polarity should not matter......... now if you have #1 injector on the number #3 cylinder.......now you have problems...

you have SFI, which means injector number and cylinder number have to be the same.......i more year earlier and you would have batch fire like my sled......

need more info to help........with this crop job youve done, im not sure exactly what schematic changes you have made if any

What do you mean when you say "the colors were reversed."? There are two wires to each injector.... the pink one is +12V from one of two fuses for the injectors. The "colored" (non-pink) wire goes back to the PCM and provides a ground to fire the specific injector. As long as you have the correct color wire from the PCM to the injector, it doesn't matter which terminal of the plug it is on.

Once the engine is warmed up, you would be surprised how little impact the injector firing sequence has. I've driven mine (when I was running the Electromotive Opti-Eliminator) with the cam synch signal 180-deg out of phase, and you couldn't feel any roughness. And... the "batch fire" 93's pour fuel into all 4 injectors on a bank, once every crank revolution, without the slightest care for where each cylinder is in the 4-stroke cycle.

my sentiments exactly fred.... and you word its so well........

damn you know these cars in and out..........i have never had to deal with wire colors to the injectors(thank goodness)........and i am fortunate i suppose with speed density............ some would argue....

No, they were on the correct injector, but the polarity was reversed. Seeing how the car runs exactly the same, It must not make much of a difference.

I am literally pulling my hair out trying to figure out what's causing my random stumbling(rolling?) miss.. I think i'll have to force my car to commit suicide if it ends up being the opti. I've dumped so much money into everything else, if it that ends up being the problem, I'll probably have a nervous breakdown

polarity really wouldn't matter..
And as a side note, when I first got my car, after a few months I noticed that 2 injectors were reversed[3 was on 5 and vice versa] and I thought, OK this is going to run BETTER now..
it ran well before, and after, I corrected it.. with no noticeable change at all...