2003 Cadillac STS engine hesitates/lunges

Check fuel pressure and fuel filter. Any modifications to the air indutction system? K $ N filter or anything like that? Check TPS EGR also. EGR may be opening at the wrong time, and TPS may have a dead spot. Vacuum leaks are a concern as well, spray some TBI cleaner at the vac hoses and intake manifold at gasket seam areas, if idle changes, you have a leak!

hello,
no modifications to the air induction system. what's a K $ N filter? sorry I don't know anything about cars. I will print this out and take it to the dealer auto serivice ctr.
Thanks for the suggestions.
Ramona Verburgt
milwaukee, wi
I'm really concerned about getting this taken care of b/4 the snow flies! :)

hi,
I also forgot to say that I can go 1, sometimes 2 days without this happening, and other then that, the engine runs great and I don't lose any power. Thanks.

K&N filters replace the existing filter with a conical shaped oil soaked one, these cause MAF sensor problems over time, cakes the sensor with thick greasy residue. Have you had it scanned for any trouble codes? Autozone does it for free, write down any that are found, and ask for "freeze frame" data too!

well they found a code, it was p13xx I can't remember. it said something about a wire harness circut ??. anyways after 480.00 dollars it cost to repair. I took it home and a couple days later, the car is idleing very rough, and there still some hesitation, and the check engine light came back on this morning! I'm very frustrated and sick about this. fuel injectors?? I don't know, but I'm taking it back there today.

I took my car back in this morning to the dealer and they called me a couple hours later to tell me that the code that came up this time is P0300. they said the Cyclinder#5 is misfiring and my car needs an ignition coil pack and all new spark plugs! That is going to cost me 1100.00! tell me, does this sound ligit to you? I'm at their mercy because I know nothing about a car. I think I will try to trade it in for a Honda Accord!
Thanks,

Seems very high for plugs and coil, try a local repair shop for price comparison. Believe it or not, some Caddy's need the enging lifted to change the plugs. Ask if yours requires this.

2003 can be a bit pricey due to the air injection system that interferes with the rear bank(Bank 1) that contains cylinder #5. I can understand the coil failed, but you should not need the plugs, at best a #5 plug due to fuel fouling. The plugs are rated to 100/150k miles, and are probably in the neighborhood of 10-15 bucks apiece, and I am sure there is additional labor for the plugs. If you choose to repair, I would just get the coil, and only the #5 plug, if need be.

Yep, they way they build this stuff, Hyundai 2.7 requires the removal of the upper intake to get at the rear plugs, NUTS!

I had the work done on my car, they replaced all plugs and the coil pack. That was almost a week ago and so far so good. What's next, I'm now on pins and needles wondering what will need replacing next??!! I've come to the conclusion that you can't have a car after the warranty runs out. It sure sucks considering what we all pay for a certified used or brand new car these days.

May have just needed the tune up, it could be fine!