KOER code 543 help!!

Discussion in '1994 - 1995 Specific Tech' started by 95Cobra302, Nov 8, 2011.

  1. Fuel pump circuit open, pcm to battery. Anyone figure out what the heck this code is?? Car has been running like crap, has a bad miss through all rpm.

    Think its maybe is the PIP crapping out. Hooked up a timing light and took awhile before the #1 cylinder would light it up. Seems intermintent sometimes, at idle the rpm will jump up a bit and it will be fine for awhile.

    Hooked up my scantool and my spark is jumping from 20 degrees to all the way up to 30 degrees at idle. Is it supposed to do that??????
  2. Just got a code for one of my O2 sensors with rich condition. Looking at my scantool, one of the O2's is sitting at 0.00 v.

    Can anyone make anything of all this????
  3. Maybe with that bad O2 sensor your car is running on limp mode which in turn makes it run like crap?
  4. Rich and Lean O2 codes is almost normal on these cars. When I had long tube headers the O2 sensers were pretty far away and I always got lean codes. Even had lean on side and rich on the other. You can change them, reset the codes and it should be fine for awhile.

    Have you changed the fuel pump yet on this car? With fuel pump codes I wouldn't be driving around like that in case the pump takes a crap on the road. Calling a wrecker isn't fun. Now's the time to upgrade to a 255 or 340LPH if you haven't.

    It's normal to get O2 fuel and rich codes if your car isn't getting enough fuel to the motor hence the reason it's running like crapola.
  5. I mean it runs bad, can't even get up to speed. Even in limp mode with a bad 02, it's designed so you can at least drive around. Had bad 02's 10 years ago when I bought it and it drove fine.

    One thing that bugs me is the 02 readings on the scantool. One O2s is around 2.50v or so, and the other is 0.00v Is that normal??? Doesn't sound like it.
  6. Check for a bad ground or power cable or simething. Sounds like a bunch of things aren't getting power. When an O2 goes bad, it usually doesn't read O. It usually doesn't cycle as fast.

  7. Ok, just an update. Usually I got a left side O2 code and code 543. Just swapped O2 sensors and ran a bunch of tests. Now I getting just code 172, which is O2 sensor lean condition right side.

    Obviously that sensor is the one testing bad, I'm thinking when it was on the left side it was tripping code 543, since it's not showing that code now that I moved it to the right side.

    Also put a little fresh gas in the tank with some seafoam. Since it isn't a daily driver I hardly ever drive it. Seems to idle pretty good though, nice and steady. Tires are flat spotted since I didn't move the car in ages so it will be awhile before I can drive it and check for hesitation.