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07 3.6L Cadillac CTS Rough Idle, Reluctant Start

Hey everyone,

I’ve got a 2007 Cadillac CTS with the 3.6L engine. The car has begun idling rough when stopped at lights, parked, etc. A few days later, it also began starting reluctantly. The rough idle varies in intensity, but is almost always present. The CEL is not illuminated and the car seems to run fine when not idling.

A few months ago, the car began running like a lawn mower and the check engine light came on. It turned out to be a misfiring cylinder. I had all the plugs replaced along with the ignition coil for that cylinder.

The car ran great for a few months after the repair, but now this rough idle problem has appeared. Has anyone experienced this with a CTS? Do you think it’s related to the repair a few months ago? Any suggestions?

The problem might be with the Drive-By-Wire throttle body.

The throttle body on your engine doesn’t use an Idle Air Control valve. Instead the computer controls the throttle plate on the throttle body to allow the proper amount of air at idle.

The next time the engine runs rough at idle, with your left foot planted firmly on the brake pedal, with your right foot slightly tip into the throttle. If this smooths the idle out the problem is with the D-B-W throttle body.


Thanks Tester, it sounds like that may be the problem. The engine does instantly smooth out when at any RPM level above idle.

@BigT3x if you have the LY7 ENGINE, GM has published many bulletins about this engine.

Please post your fault codes, and I will try to help you.

Im having issues and all the throttle cam crank senors reading low about 15 different codes had two different kind of plugs in it. Someone said its probably timing chains. I just bought the car it takes srveral revolutions to start then lacks power rough idle but does run .its 2007 cts 2.3

I had the same problem. You have to use full synthetic oil 5w30 and 89 octane gas as per owners manual. You can go with cheaper oil and gas for a while but condition will return. A bottle of fuel injector cleaner works wonders as well.