: Rough Idle and sputter at low rpms

02-17-11, 09:34 PM
I have a 98 Catera that i just purchased about a week ago, it had a rough idle when i bought it, and it sputters and shakes a little bit when I first accelerate but it comes out of it around 2000 rpms and runs fine until i got to take off from a stop, I found a vacuum line that isn't connected on the backside of the intake manifold, all 4 vac lines comming out of the manifold are connected correctly the one that is loose was laying across the 4, it comes up from the bottom side of the motor but I can not find where it needs to be connected, i hooked the car up to an obd2 and it said evap system leak, could this be the problem for the rough idle and sputter? Any help would be greatly appreciated, I love the car and I am just learning about it. Also the guy i bought it from had it for a year and he ran cheap gas in it the whole time, I have put premium in it since I have had it and also 2 bottles of techron fuel system cleaner and it seems to be helping to reduce the sputter but it is still there?

02-18-11, 07:35 PM
I think its the vacuum line that goes to the crankcase but not 100% sure, if anyone knows where it hooks up to I would greatly appreciate it, I took I IAC valve apart and cleaned it and it has seem to take the rough idle away almost it is still lightly noticeable but im thinkin if I can get this vacuum line figured out it will take it away, it still kinda chugs a little bit when it pulls a hill but not near as bad as it did before the I cleaned the IAC. It runs beautifully minus the 1 minor issure.

02-18-11, 08:46 PM
A couple thoughts... when sputtering under a load (acceleration) possible spark/ignition coil problem..its demanding more and shorting out.. Im not sure if the 97/8 have the ignition coil or wires.. I have 2000. also as far as the high octane fuel.. I used it for the first yr... then over the last 3-4 months I have only used regular.. I didnt notice any differance.. honestly think the 10% more per galon is a waste.. I noticed no change in fuel milage, or performance.. no pinging or anything.. I mean its only a 3.0 with 200 hp... its not a high HP larger motor... refer to the l300 saturn .. same engine.. preimium is not required ... Good luck!