Mechanics

ROUGH IDLE IN GEAR

2001 Saturn SC2 • 110 miles

My stepdaughters Saturn when in gear (auto) has a rough idle just above the point of stall. SES light is on. Codes at Autozone are PO133, PO442 and PO303. Car runs ok above idle (regular operation). If you take the car out of Rev. Or Drive and put in Park, the rpm's shoot abnormally high. At start up the rpm's also shoot up a bit but that may be a choke issue. As to the codes, I pulled the number 3 plug and it appears to be ok. She did purchase a new fuel cap. The hose from the cam cover to the air-intake had a split at the intake and I corrected that. It then ran mildly better at park idle but not while in gear. There are more options for repair than dollars. Any help on which direction to go would be appreciated. Thank you.
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JimboD
July 2, 2012.



The first code is a failing oxygen snesor, the second code is an EVAP or emissions system leak and the last code is not on my code chart. There is a P0300 indicating a misfire and a P0403 EGR Solenoid control which is an emission control unit.
There are several issues you are dealing with and some are related to vacuum leaks which would cause a racing idle and the poorly functioning emissions and Oxygen sensor are probably the reason it runs rough. The EVAP leak could probably be fixed rather easily as it runs from the intake manifold to the exhaust. The only way it might get expensive is if the exhaust is rusted out and leaking around where it connects.
I think I am going to give you 2 diagnostic walk throughs that will explain the issues you are dealing with. The emissions issues are probably items that can be cleaned and the EVAP leak can probably be fixed for a low cost. It sounds like the car has a lot of issues as if it were overheated at one time or is operated in a high tempoerature climate which has taken its toll on plastic items and rubber items and seals. It also is in need of a fuel system cleaning which would help clean out the emissions items. You could either take it apart as I mentioned and clean it which is best or get some SEA FOAM or BG44K. The BG is better but costs more and you will have to go to a car dealership to get.
Vacuum leaks are more damaging than dirty or cloged emissions items. However, the sum of these, especially the oxygen sensor, is more than likely making the gas mileage very low and costing money as you drive. So, you might invest in some parts, labor and/or some of your time and clean the intake and replace some of the failing emissions parts and the oxygen sensor.

The diagnostic walkthroughs will give you an idea of which problem is causing which symptom in more detail but more than that it will better explain repair. Just use the links below.

http://www.2carpros.com/articles/engine-idles-too-high

http://www.2carpros.com/articles/engine-misfires-or-runs-rough

Just to add to this one i have never seen a front o2 sensor cause the engine to run rough on those cars.For the code P0133 replace the front o2 sensor screwed into the exhaust manifold.Get a universal o2 that you use the connector on the old sensor there way cheaper.I got one for my saturn real cheap on http://www.rockauto.com.For the P0303 what type of spark plug do you have in the engine?Hopefully not platnuim plugs?So did the gas cap fix the P0442 evap small leak?I would would also inspect the outside of the plugs and inside of the spark plug wires for black carbon.

Saturntech9
Jul 3, 2012.
I would also look for a vacuum leak. Also how high does the engine idle?Also have you checked the coolant temp sensor?They have a high failure rate and will cause high idles and alot of other things. Also inspect the inside of the connector going to it if the terminals are green or blue instead of silver you will have to replace the connector also.

Saturntech9
Jul 3, 2012.
Also under the intake manifold you will find the canister purge solenoid see if both vacuum hoses are hooked to it.I have one of the hoses off causing the code P0442 and cause high idle issues.

Saturntech9
Jul 3, 2012.
Update: I have changed the O-2 sensor at the exhaust manifold. New plugs and wires. Would idle at 900 and drop to 700 when in gear. After fixes, idles at 1000-1100 in park/neutral and just below 900 in gear. When going from gear to neutral or park, RPM's shoot to about 1900 and gradually winds back down. SES light is still on. Only remaining code before today's repair of plugs and wires was the 303 code (misfire at #3 cylinder). Have not checked purge yet. Idle is rough in gear still but not as bad as it was. Runs fine at speed. Before repairs started, had step daughter put premium in (92 octane). We are in AZ and vehicle deals with extreme heat. 108 today, 112 tomorrow. Park/neutral idle seems to be ok (maybe a little high on the rpm side but not rough). Will take back to A-zone tomorrow to check code. Guy reset it today and said to drive it for about 100 miles. Any ideas? Thanks

Tiny
JimboD
Jul 9, 2012.
I hope you put stock copper plugs in the engine not platnuim plugs?Also for the high idle try this unhook the negative battery cable for like 1 min then hook it back up. Then see how it idles let me know what you find.

Saturntech9
Jul 9, 2012.
It's toast. We kept getting the misfire #3 cylinder code. Compression test done today. 0 psi. And when the wife drove it home, rod is knocking. Sold car this evening.

Tiny
JimboD
Jul 18, 2012.
And thank you for the assistance.

Tiny
JimboD
Jul 18, 2012.
Your welcome thats what were here for sorry to here the outcome of the car though.

Saturntech9
Jul 18, 2012.