My Saturn is acting funny. The past couple of days when I try to start the car is starts but chokes really bad and dies. Now it doesn't happen everytime but when it does I can get it running by keeping the rpms at 2000 or more then switch it to drive and it runs smooth. Other than that some times I put it in neutral or park and the rpms go to 2500 - 3000 and sit there unless I put it back in drive or reverse. I have an engine light that codes to be O2 sensor and fuel. Auto zone say to check the fuel pressure which I did there was a hook up for it and I got a constant 43 and after I turned it off I got a 40 that stay put. Any ideas or help on this would be appreciated.

 

Please post the codes read from the car... They can help us tell exactly what is going on and why the engine will choke at idle... Have the spark plugs been changed? Wires? Coils?
Do you have a loose vacuum line? There are many reasons for idle troubles...


Now, that being said, technical posts of this nature don't really belong in the new member intro area... I'm not a moderator, so I can't move the thread...

 

I will move the thread, and delete the other one you posted. This section is for New Members.

 

Sorry about posting in the wrong spot I had clicked on the wrong thing but I will have to wait after work to get the codes from the part store.

 

The codes were code P0056 indicates a fall in the bank to censor to H02S heater control circuit for a predetermined period of time air codes read P0056 heater control circuit bank to sensor to next one P0161 HO2S heater performance bank to sensor to next code P017130 trim system lean bank one next code P0174 fuel trim system lean bank to. I replaced all 402 sensors and now when I go to park or neutral it revs up to 3000 RPMs but not when I'm driving

 

P0056 HO2S Heater Control Circuit Bank 2 Sensor 2
P0161 HO2S Heater Performance Bank 2 Sensor 2
P0171 Fuel Trim System Lean Bank 1
P0174 Fuel Trim System Lean Bank 2
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P0056 and P0161 point to the heater circuit for the O2 sensor in the downpipe immediately AFTER the pre-cat. Bank 2 is the side of the engine with the 2-4-6 cyls.

From what I've read, Bank 2 is the side nearest the radiator--PLEASE CONFRM.

Replacing that with an OEM style sensor should take out P0056 and P0161.

The other post precat O2 was not throiwing an error and probably did not require replacement.

Use of a universal splice in O2 sensor doesn't seem to work well w the Saturns in general.
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Clear all the codes ans see if the 0171 or 0174 come back.
It is rare for two lean codes to pop at the exact same time for different banks -- UNLESS the issue is further upstream before or at the intake manifold that this leading to a lean fuel mix. I've seen the MAF mentioned as the culprit, but I'm sure one size does not fit all. It is expensive, so be sure on your own that this is the problem.

If the 0171 and 0174 each popped up individually, I could see suspecting the pre precat O2 sensors. But since they came on simultaneously, I see no reason to indict the pre pre cat O2 sensors for both banks at the same time. So I'm not sure if replacing the pre pre-cat O2s was necessary.

As your codes are for running lean, this may be correctly indicating the condition but obviously it doesn't tell you why/where the problem is.
RPM that high often indicate vacuum leaks or situations where the engine is pulling in extra air not through the air intake system, but somewhere else.

Since this air is "unknown" to the PCM (unmetered air), the PCM sets up what it thinks is the correct air/fuel ratio based on feedback from various sensors, but the unmetered air comes along and adds air to an otherwise "desired" air/fuel mix, causing the mix to have a higher % air and therefore the mix is "lean".
Again the EDIT : MAF (not MAP) comes to mind but independently confirm before shelling out the $$
It is possible that the intake manifold gaskets on both sides are leaking, but for both to show up at the exact same time is too much of a coincidence for me. Still, you can check by spraying around the intake manifold where it meets the block (on both sides). If you hear a change in rpm you've found at least part of your issue.
Probably want to try same thing around throttle body gasket area where it attaches to the intake.
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So after re reading your post

• did you clear the codes after completion of work on it?
• did any of the four codes come back after you did the O2's?
• do you have any old or new codes appearing?

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EDITED for completeness and typos, 1/5/15

 

Kind of reads as a clogged converter to me. Does the exhaust smell like sulfur or rotten eggs?