Hey Scotty! I'm stumped! So here goes. The vehicle is a 2003 Cadillac CTS 3.2. The car will run…


Hey Scotty! I'm stumped! So here goes.

The vehicle is a 2003 Cadillac CTS 3.2.

The car will run great on startup, once idle hits under 1000 rpms, check engine light blinks and idles rough (check engine light blinks). If you hold the rpms above 1000 it runs smooth.

I've done this to the vehicle so far:

  1. Heads are brand new rebuilt
  2. Timing belt new, timing set brand new and timing marks are dead on
  3. Spark plugs new, coils new, crank sensor new, coils are firing (spark test done)
  4. Good compression on all cylinders (engine not warm): 1st Crank 60 psi, 120 psi max, wet test 130 psi.

When I pull the spark plugs on 1-3-5 they are wet and smell like gas. As I said before, the spark plugs are firing, I tested them out with a spark tester. Seems like it's almost pumping too much gas. People have suggested stuck injectors, but I don't see how 1,3,5 would get stuck all at the same time. I think it's something controlling the left bank of the engine (oxygen senor possibly (upstream)). I hooked an live scanner on it, when the engine light starts blinking the Fuel System 1 and 2 goes in to OL-Fault mode. Rev it back up above 1000 rpms and it goes in to CL mode and engine smooths out. Pretty much at a loss and out of ideas. I even unplugged the coil pack with the engine running and the misfires get worse, plug it back in, it still misfires, but is smoother.

Link to what the car is doing: https://youtu.be/h6YNDZPf2_s

Comments (2)
No. 1-2

Maybe, I'm not understanding. There is no difference in pressure on the compression test all cylinders on the engine are the same. Are you suggesting the head gaskets are bad or the heads are bad?



classic signs of head gasket problems, you had heads done but guys often do crap work these days, especially on those crappy caddie enines known for problems