I am having a very frustrating time with my 2001 S40 1.9T randomly stalling when coming to a stop.

The history:

I had a check engine light come on while on a trip. the car was running fine but this is when i first experience the stalling. I had the codes read at an Auto Zone and came up with four, P0301, P0302, P0303, & P0304. These were for a cylinder misfire on all four cylinders.

What I did:
* Replaced all four spark plugs
* Replaced both ignition coils
* Replaced MAP sensors
* Replaced MAF sensor

This did not correct the problem. I want to mention that the car runs fine except for the random stalling when I come to a stop and then starts right up. It also idles rough when started for the first time in the morning.
I had the check engine light codes cleared before I replaced the above parts. The light never went out after replacing the parts and I am now getting the following codes:
PO326 - Knock Sensor Condition
PO101 - MAP/BARO or MAF/MAV sensor condition
PO172 - Fuel trim bank one condition

At this point I don't know what to do. I have a feeling it could be a vacuum leak issue, but after a visual inspection I can't see anything that looks problematic and I don't have any testing equipment.

Any help anyone could offer would be greatly appreciated,

Chris

 

I did not see where you replaced the spark plug wires on the other 2 cylinders? Did you replace the fuel filter too? How long since the top O2 sensor was replaced (controls fuel trim feedback)?

I'd complete the tuneup with the spark plug wires, fuel filter, and O2 sensor. Then reset the codes and see which ones come back. Also if you use regular grade fuel try running premium grade to see if the knock sensor issue is from regular gas usage. If the car senses knock it will try to pull timing and may cause your stalling. The knock sensor is a $100 at RockAuto, ouch.

 

Thanks for the advice. I have ordered the parts and will update my results.

Chris

 

Replaced the fuel filter, O2 sensor air filter and the spark plug wires and always use preimum fuel. No help. I think my only option at this point is to take it in and see what the diagnostic say $80. I have obviously spent a lot of time and money replacing thing that have not improved anything. Very aggravating.

 

Did you clear the codes and they all came back?

 

No, I will respond back with the diagnostic results.

 

OK, The Saga continues.

Had the diagnostics done at Tires Plus. They said that there was a problem with the MAP sensor. I told them that I had already replaced it but said that it was putting out more than it should (something about 9 vs. 6). I agreed to let them do it ($321). They claimed that the Check engine light was off and the car had been road tested and it was fine. Picked the car up after closing the light was on and the car stalled on the way home.

Brought the car back the next day and the said they found a broken vacuum hose and that everything was working well. Picked the car up, check engine light was off and everything seemed OK.

Started the car up this morning and the check engine light was on and the car stalled on the wary to the store.

Pulled the codes at Auto Zone and came up with these:

P0234 - Turbocharger Overboost Condition
P0171 - Fuel Trim Bank One Condition
P0101 - MAP/MAF Sensor Condition

Seems like I just keep putting new parts in and throwing money at this car with no result.

Any Ideas?

 

No dealer nearby?

 

I was having similar issues, I replaced fuel pump and fuel pressure regulator on my 2000 s40, now she just stalls when put in park. She doesn't always stall but the idle dips way down and can cause her to stall and she can get a rough idle while in park. (my daughter named her Lola so I am use to referring to the car as a female.) I need to hit the auto parts store so i can reset the codes.

Before I replaced those parts I was getting a code for random miss-fire bank one. and several others.

 

If you have a Harbor Freight near you can pick up a code reader for very cheap.

For the the stalling I'd try cleaning the Idle Air Control motor. You need a new gasket for this as the old one is thin paper and tends to tear. Spray out any carbon and gunk inside the air passage.

Don't trust the misfire indication for a specific cylinder. Each coil fires 2 cylinders and the ECM will have a hard time figuring out which is which. If you get a misfire and new spark plugs do not fix it, then replace the coils and wires. One person here actually found a hairline crack in a coil and fixed it with epoxy. I've never had such luck.

 

where is the fuel filter located on the 2000 S40?

 

I have the same problem and had spark plugs replaced,wires and coils. still he same problem.

 

Driver's side, under car in front of back wheel .There is a plastic panel to remove but you can feel the filter before removing the panel.

 

If I'd done everything as previously posted and the problem still persisted then I'd replace the IAC motor. But that's just my opinion. Let us know if you find a solution.

 

would anyone tell me about the fuel pressure regulator location in the engine? I also have a PO133 code. what does it mean?

 

P0133 = Oxygen Sensor Circuit Slow Response (Bank1, Sensor1)

The FPR is mostly covered by a black plastic cover over the throttle/throttle body. The FPR is mounted using 1 screw to the fuel rail, on the drivers side. You have to disconnect the fuel line, the intake vacuum hose and the mounting screw then pull it out of the fuel rail...all of 10 minutes to replace.

 

P0133 = Oxygen Sensor Circuit Slow Response (Bank1, Sensor1) Which is the top O2 sensor, the one that adjusts the air/fuel ratio. How long has it been since you replaced the O2 sensor? It's due every 100k miles.

 

I have the same problem with my 2001 s40. I cleaned the mass air flow sensor and the check engine light didn't go out so I cleaned the electrical connector to the MAS and the check engine light went out and gave me enough time to get the car inspected. As soon as I left the garage with the new inspection the check engine light came back on. The car still stalls every now and then and I always put in premium gas. The light goes out sometimes and then comes back on. I think that a new sensor should fix it but I'm not sure now after reading your posts.

 

The MAF sensor is a major component in proper fuel delivery. The O2 sensor is not, it's just feedback to fine tune the fuel delivery. If the MAF is bad then it will need replacing. A bad O2 sensor normally causes bad gas mileage, but it won't leave you stranded.