I have a 2008 Volvo s60 and it stutters occasionally at idle - ALMOST dies - but only lassts a half a second or so - There is also a P0135 code - so I changed the O2 sensor. (P0135 Oxygen Sensor Heater Circuit Malfunction (Bank 1, Sensor 1). The check engine light disappeared but the code is still there, even after clearing it, and it says 'current' on the scanner. It still stutters at idle. I checked the voltage of the battery while running and we're good at 14+v. Also, across the fuse, good there too. I pulled the MAF and am going to clean it off and reinstall but it looks really clean as it is. Thoughts?

 

Did you reset the code yourself after replacement? The exhaust system is one of the last to complete its drive cycle. It will require a decent amount of driving before its complete and will correct or the code will stay. Your car stuttering at idle may be because of something else, maybe a small intake leak somewhere? When cleaning the MAF, make sure to use MAF cleaner and not brake clean, its too aggressive for the sensor.

The code indicates that the sensor is not going into closed loop quickly enough to satisfy the ECU. This can mean that even though the engine is warmed up, the exhaust isn't warming up fast enough which could mean you are lacking air in the combustion chamber, ie an intake leak.

I had a pretty bad intake leak on an 06 s60 I used to have and it never threw a check engine light, even though it caused my car to sputter and stall.

I would inspect all intake hoses, run a smoke test on the intake if you have the means to do so, if not, starter fluid sprayed on the intake hoses in small areas at a time to see if the engine rpm's go up after a spray is a way to test as well. The corrugated hose from the intercooler to the throttle body can easily break on the bends after all those years.

 

The code did reset and doesn't come back. Still having the sputtering problem.

 

I would look into your fuel trims, and try to get the car scanned by a volvo mechanic or an indy with VIDA which will read volvo specific codes from each module. There's many different codes that be present but do not trip a CEL.

Do you know if the PCV system has ever been serviced on that car? You can check your PCV health by removing the oil fil cap while your car is idling and seal your palm over it, if you feel suction, that is good, if you feel pressure, it needs to be serviced. You can also try the "glove test" if you dont feel much. Just place a latex -type glove over the filler cap and it should suck it in a little bit, if it inflates the glove, no good. There's many videos on youtube.

A worn out PCV system can mess with your idle a lot.

 

failed PCV systems can also allow oil to mist into the intake messying up the MAF and throttle body. a quick inspect of the intake tubing to the throttle body may be in order and if dirty clean with some CRC MAF cleaner (not carb cleaner). Other possible causes are vacuum/intake air leaks and issues with the ETM.

 

Tore the front of the engine down and removed the intake manifold, much of the air pipes/hoses - the big ones, not the vacuum tubes - are coated in oil. So, i'm going to change the PCV system and I'm seriously thinking about just doing the head gasket since it's almost all apart anyway and has 180k miles.

 

So, what started as a PCV system repair has turned into a Timing belt, tensionoer, idler, water pump, and headgasket! Why you ask!?! well, lemme tell you!
When i was doing the PCV system removal - i ran into an issue with access, that bottom left bolt on the intake manifold! so i took off the thermostat housing and one of the radiator hoses - figured i'd just fill it back up - but i saw copper flakes in the fluid - I hear that means there was some kind of coolant leak - either head gasket or radiator - since i dnot see any signs of radiator damage, bent fins, or any stains, i'm going with head gasket - meaning - off with it's head!

In order to get the head off - i have to take the timing belt off too - and at this point, why not also make srue the water pump is inn good shape! GOOD THING TOO! the timing belt is cracked and raggedy. Maybe had 1k miles left on it... so... this is a big project!

 

For future reference, that bottom left bolt does not need to come all the way out when doing a PCV service. What you can do is cut the bolt hole on the outside edge of the new gasket in that location and use some universals and 1/4" drive to tighten the bolt after.

But it is good you dug into it to find out about the timing belt. You never want one of those to go. Godspeed in your repairs

 

OK! here we go! I have done a head gasket and all affiliated seals and gaskets - did a water pump and timing belt - v belt too. The pcv system is replaced, all fluids, oil and antifreeze. the MAF sensor is new, the fuel pressure regulator/sensor that plugs into the end of the fuel rail is new. and 2 brand new front o2 sensors - still getting the same o2 sensor code p0030 and stutter issue, random stutter/stall at stop signs and a stutter/stall while idling. nothing seems to preceed these stutter events.

I'm at a complete loss as to what to try next.

Some thoughts? Volvo Boost Pressure Solenoid Valve? but what/why the issue with the o2 sensor code?!?!?!?!

HELP!

 

Here is the veiw from the live data of this happening - can the PEM be sending too much fuel pressure through the line?

 

Were you just holding down the throttle during that live data? Those solenoids are a common replacement in the P2s. I ended up upgrading mine as I was running higher boost. People do often run an inline air filter for the input to catch the oil vapors and increase the solenoid life.

I ask the throttle question because the air is jumpy.

The reason you get an "o2 sensor code" is because the o2 sensor regulates the air/fuel mixture. So when the ratio is running lean or rich, it will trip the code and it will correlate with the sensor responsible for saying the data isn't matching up to where it should be.

Does the car idle fine and you only see issues like this when driving?

 

I was not holdin gdown the throttle. it was at an idle. It's an intermittant issue and this will stumble and stutter occasionally. and the code for the o2 sensor changed with the new o2 sensor. i'ts now 243c o2 sensor heating signal too high -

I sat with the computer on the car for a while and the throttle body potentiometers have a spike the instant before the details you saw above happens. So, i'm thinking the throttle body needs to be replaced...

Still stuck on the 02 sensor issue - gonna clean the connectors on the ECM and the o2 sensor and see if that helps.

 

The throttle opened up to allow more air in because of the decrease in idle RPMs to prevent the engine from stalling. I don't think you need to replace it.

When you did your pcv service, did you clean out the ports going from the trap to the block? Did you also replace the banjo bolt, crush washers, and the pcv nippIe it connects to? Banjo bolt location is under the intake on the passenger side.

 

Replaced the throttle body. Replaced the turbo boost solenoid. Replaced the fuel sensor on the rail and IT'S STILL STUTTERING AND STALLING - only at idle.. The vacuum hoses are fine, no tears or leaks. The pcv system is new and passes the glove test. I am so frustrated.

Could it be the ecu?