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2006 S40 2.4i Intermittent Stalling (p0101)

33K views 312 replies 16 participants last post by  Ksvolvo 
#1 ·
Hello all. I apologize about this being about my 3rd or 4th thread on this issue, but it seems that every time we believe we fixed it, the problem comes back. Anyways, ever since we bought the car, we've had a P0101 code (MAF sensor). The issue would be that when coming to a stop, the car would drop RPMs to a near stall. Then it got worse- the car would actually stall. Then it got even more worse, and while driving at highway speeds, the RPMs would drop to around 800 while cruising. The car does hesitate when accelerating and sometimes stutters a bit. We replaced the MAF sensor, MAP sensor, FPS sensor, spark plugs, cleaned the throttle body, replaced the O2 (oxygen) sensor, and also replaced the coolant temperature sensor and thermostat (coolant problem). Anyways, we've had it into a Volvo certified service shop (not dealer) and they tested for vacuum leaks.They found one and sealed it with tape. They also replaced another hose they suspected could be leaking. We ourselves (my dad and I) also replaced the PCV hose when changing the sparkplugs. At one point a P0172 (too rich) code came up, but it cleared after replacing the coolant temp sensor and thermostat. The stalling issue did seem to go away for a while (with the RPMs still dropping when coming to a stop) but alas, the check engine light remained on with the P0101 code.

Today I was out driving and the car stalled when turning the corner to pull onto my street. Started right back up fine. Then later I was driving and accelerated from a stop light. Then the car in front hit his brakes to a complete stop almost immediately after, as did I, and the car stalled. It again, restarted just fine, but I was almost rear-ended because I had to start the car again.

I will link a video below to what I believe is a vacuum leak, but I would like the opinion of everyone on here. You can hear very loudely a hissing/whining noise over the sound of the engine. The noise SEEMS to be coming from the hose that has the little red inlet on it as well as the top on it (the tape the volvo repair shop put on). But I can't tell if it is coming from this hose or the whole brake booster system behind the engine. Is this the sound of a vacuum leak or something else? We tried carb cleaner spraying and could never get the sound of the engine to change.

Video: https://goo.gl/photos/RSV5Cs9HNSytFMAq7

Any and ALL help would be greatly appreciated, as we just want this fixed!!

Also worth noting the car is NOT a turbo model, it is 2.4i Car has 118061 miles on it.

Thanks again!
 
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#2 ·
As far as the stalling when coming to a stop, I had the exact same issue with my car for about 5 months. It got so bad at one point that is was nearly undrivable. And as it got worse it started making the car go into limp mode after it stalled so I would have to turn it off and on numerous times until eventually it started as normal. Very frustrating.

Oddly enough though, I never had a CEL from it. The only code I got was seemingly relating to the throttle body voltage so I thought it might be a connector or the throttle body itself. Shortly after it was at its worst, the problem simply disappeared and hasn't come back since.

I know that isn't much help, but it's a weird problem that not many people seem to know a lot about. I hope you figure it out because I'm just waiting for the problem to come back on my car
 
#3 ·
As far as the stalling when coming to a stop, I had the exact same issue with my car for about 5 months. It got so bad at one point that is was nearly undrivable. And as it got worse it started making the car go into limp mode after it stalled so I would have to turn it off and on numerous times until eventually it started as normal. Very frustrating.

Oddly enough though, I never had a CEL from it. The only code I got was seemingly relating to the throttle body voltage so I thought it might be a connector or the throttle body itself. Shortly after it was at its worst, the problem simply disappeared and hasn't come back since.

I know that isn't much help, but it's a weird problem that not many people seem to know a lot about. I hope you figure it out because I'm just waiting for the problem to come back on my car
We did expect it was the throttle body, which is why we actually cleaned it at one point. This does not seem to be the issue though (I believe). We're going to continue to inspect it. The cause does seem to be a vacuum leak but we can't tell if its a line in the break booster or somewhere else.
 
#4 ·
Well it could be the TB. Realistically, unless you have VIDA and DICE hooked up and monitoring the commanded vs actual voltages, you can't rule it out.

I would suggest a used one off ebay to do a replacement, and see if the problem still exists. At this point you either have an issue with that or an issue with yoru injectors dumping too much fuel.
 
#5 ·
I would suggest a used one off ebay to do a replacement, and see if the problem still exists. At this point you either have an issue with that or an issue with yoru injectors dumping too much fuel.
But would the car still be throwing a code for P0101 - MAF Sensor if it is a bad injector issue or something with the TB?

Also, is it possible to check voltages for the TB inside of torque?

Alsooooo, what should the throttle body voltage be? Voltage from the battery or voltage of the actual chip inside the TB?

If I were to buy a used one, would i be able to program it to my car using one of the chinese VIDAs and a free copy of the 2014 software? or would i need to register for it? Thanks again
 
#8 ·
Okay- the coolant issue. Basically we noticed my coolant was leaking one day. The upper radiator hose was leaking. So we replaced it, the thermostat, the engine coolant temperature sensor, and flushed all the coolant and added new coolant to the system.

And yes the only code is P0101. No TB code. But yes another thing I was going to ask if it could be the wiring for the MAF? if you watch my video in the original post you can see the video of what I believe is a vacuum leak- can anyone elaborate on that?
 
#10 ·
This is probably stupid, but is there anyway to check the throttle body (with the car in park) to see whether or not it opens or closes? Like, can I somehow see if it's closing all the way or opening all the way with it connected to the car's computer, but with me actually seeing it?

And what is this Porsche upgrade? For the TB? Heck, if we have to replace it and there's an upgrade I wanna know about it!
 
#11 ·
Actually disregard about the upgrade. But either way I think we might be looking at the TB swap. I'm in the process of getting VIDA Dice.

Is it true that they are plug and play? Everywhere I read says the TB has to be programmed.

Also, just curious, but did you watch my video that I put a link to in the first post? In the video you can hear what sounds to be a vacuum leak but I wanted to check if it is this it if it is something else I'm hearing. Can you watch and give me your opinion?

Thank you again!!!
 
#12 ·
Maybe this video will also offer some more insight... This is back from late January. This video is a screen recording of the Torque Pro app running on my phone with many different guages up. In the bottom left corner there is a vacuum reading, and in the top right there is RPM. All of the info SHOULD also be helpful as well. If anyone can watch this video and please let me know if this is how the vacuum should be behaving or if it should be doing something different. I know that vacuum is lower at higher engine load/ RPM. Thank you all again.

The video: https://goo.gl/photos/AcxR6XhHDiw3KmM17
 
#13 ·
So you can get rid of that Air Pressure gauge as that has to be a calculated value and on a naturally aspirated car it really isn't worth much. I am assuming the yellow marks on the dials were the maximums that were acheived at any point in time.

The car looks like it behaves ok, from WOT to foot off the gas deceleration. It seems like if your car does stall, it would really help to have this running to see:
if your fuel pressure goes above/below 55psi - means your fuel pressure regulator isn't working right
if your manifold vacuum goes above -23inHG - means your TB plate is shutting completely and your car is losing its access to air.
If your vacuum goes much lower like -15inHg when it stalls we know you have a vacuum leak still that takes some heatsoak to become a problem.
if your MAF drops to 0 or like some random other number you know it's a wiring or MAF issue.

I'd only have the fuel pressure, MAF sensor, and manifold vacuum gauges on the screen, you really don't need anything else but those three. then when the stall hits check it out and see what each one says.
Also, according to the sticky in the DIY section, the Porsche TB upgrade was plug and play, but ask MNIWT to verify as that was what he said in his post.
 
#14 ·
Yeah, the reason I have all of the gauges is because I was trying to look and see how everything behaved.

Also, I thought I mentioned this, but if the car doesn't stall, it still behaves weird when coming to a stop. Whenever I come to a stop, the RPMs drop to around 400 and then the engine catches back up and it goes back to idle. Sometimes when coming off the highway it goes below idle, back up, back down, and up again a couple times.

Sometimes, it's been a bit weird lately, where when coming to a stop it sometimes rises in Rome and then goes below idle and then back up to idle. Which is a bit weird.

Later if I have time I'll do the gauges you said and then record and report back.
 
#15 ·
Yeah, the reason I have all of the gauges is because I was trying to look and see how everything behaved.

Also, I thought I mentioned this, but if the car doesn't stall, it still behaves weird when coming to a stop. Whenever I come to a stop, the RPMs drop to around 400 and then the engine catches back up and it goes back to idle. Sometimes when coming off the highway it goes below idle, back up, back down, and up again a couple times.

Sometimes, it's been a bit weird lately, where when coming to a stop it sometimes rises in Rome and then goes below idle and then back up to idle. Which is a bit weird.

Later if I have time I'll do the gauges you said and then record and report back.
I don't have a 2.4i, but I personally believe that the manifold pressure of -22.4inHG is a bit too much. If you consider -29.95inHg is a perfect vacuum, you are 75% of the way to a perfect vacuum at your deceleration and at idle it sits at roughly -18, I think those -22.4 moments are a highlight of the issue. while driving, but due to the dynamic nature of driving, they never stuck there for very long.

Just my 0.02
 
#16 ·
I didn't even think of it like that. Later if I have daylight left I will bring out the carb cleaner and check for more leaks. I do agree the pressure is a little weird and about the whole perfect vacuum thing. Just never thought of it like that.

Also avenger, if you don't mind (and I know I keep saying it), can you take a look at the video I linked to in my original and very first post? It shows me inspecting the intake for vacuum leaks and there is a hiss noise. Maybe I can get your 0.02 on that too? I'd appreciate it!!

Thanks again. I will report back if I discover anything more.
 
#17 ·
I didn't even think of it like that. Later if I have daylight left I will bring out the carb cleaner and check for more leaks. I do agree the pressure is a little weird and about the whole perfect vacuum thing. Just never thought of it like that.

Also avenger, if you don't mind (and I know I keep saying it), can you take a look at the video I linked to in my original and very first post? It shows me inspecting the intake for vacuum leaks and there is a hiss noise. Maybe I can get your 0.02 on that too? I'd appreciate it!!

Thanks again. I will report back if I discover anything more.
Yeah I watched the original video you posted, which was the hiss as you approached the car from the front.
I also watched the 15 minute diagnosic torque app video.

You said in some past threads that both you/your dad and the dealership both found some vacuum leaks and sealed them. Is the hiss still there? The only thing that it would strike me if it was STILL there would be the PCV valve right below connected to the TB (if I recall correctly) as if it's failed it's sucking air in through the PCV system and crankcase, pulling air down past the rings and that would contribute to some issues. For a $1.00 part, it's easy/cheap to replace from your local auto parts store.
 
#18 ·
I thought the PCV hose went by where the sparkplugs go under the intake manifold? We replaced whatever hose that is that goes into the intake and goes under the manifold itself. I believe that's the PCV. But yes the hissing is still there. And what is the 1.00$ part?
 
#19 ·
So there are two PCV's in the car.
One is the integrated PCV that's part of the oil filter housing, that you can only replace in one piece and has a hose that runs up to the top of the engine (valvecover). I am assuming you replaced both of these pieces (the oil filter housing and the hose running up to the top of the engine).

The other PCV is a $1.00 valve that goes into the hose that connects to the bottom of the Throttblebody. This PCV is easy to replace as it fits many makes/models from your local auto store. If I read your paragraph right, you replaced "whatever hose that is that goes into the intake and goes under the manifold itself" so you probably replaced this one already if I am understanding what you wrote correctly so that might not be the issue when it comes to the whistling.
 
#20 ·
We replaced the one that runs from the oil filter housing and into the manifold, but we didn't replace the oil filter housing itself.

Last night I tried to check if it was the oil filter... To do so I removed the oil filler cap to see if the "hissing" noise stopped. It didn't. I believe the issue is likely something with the brake booster, and the hose is 113$ online. This is the one they tried to seal and I don't think it worked, as when I put my ear close to it I hear the hissing.

This hose is the one with the red inlet on the right side of the manifold. Do you know how to remove this hose from that inlet to make sure it is properly seated?

Is there any other ways to check the PCV system other than removing the filler cap?
 
#21 ·
You can hear a whistle when you remove the oil dipstick, but otherwise, you can put a rubber glove or something on it and make sure there's suction. If there's suction, it's good.

You can remove the vacuum hose attached by the manifold by pulling it snug. You should see the red bit pop out of the hole just a tad. Then you push the red thing in and pull the hose out. It's like a compression fitting that just keeps it from coming out, but I've had it at several different angles and it's never leaked but it might be because mine's turbo charged and not naturally aspirated.

I had often considered building one out of thick rubber tubing, but realistically, if you're stateside, you can hit an auto parts store or a home good store (home depot, lowes, etc) and get the same kind of hose in bulk for cheap by the foot and just disconnect the fittings and rebuild one or just get a foot and rebuild the section that is leaking.
 
#22 ·
I will try to see if this dipstick method causes any whistling.

Yeah I think it's something to do with that red fitted hose. It's pricy but on the 2.4i (not sure about the T5) I know it connects into several other things so it might be best to just buy it rather than making our own. Tonight when in out installing my brand new AUX input (which I'll make a post on later) I'll grab some carb cleaner and spray around the fitting to see if I find anything.

Thank you so much for all of your help though. Everyone posting here has definitely led us in the right direction. From the start we've believe it was a vacuum leak but after the independent shop couldn't find anything, we didn't know where to turn.
 
#23 ·
I believe it connects to the vacuum pump, the intake manifold, and the brake master cylinder. easy to remove. I had to have mine out when I did my motor mount over there, so it's not too difficult.
 
#25 ·
Whenever I do the whole brake booster test (turn off car, pump brake peddle until it gets stiff) it does exactly like it should. It gets stiff after a few pumps, and then as soon as I start the car my foot goes further down and it un-stiffens itself. So this seems to be working fine. But I am 90% sure that the leak/hiss noise I'm hearing is coming from this hose Here (Volvo Parts Webstore). This is the hose that the authorized service shop said they found a leak in, but then they sealed it with tape. The tape is still there, but the hissing noise can be heard from the area around the tape. The tape is in the area of where the hose connects to the top of the manifold with the little red coupling.

This is where I am describing where I think the leak is (hissing noise):


If anyone has any questions on this hose or needs more info please let me know. Again thank you all so much for your help
 
#26 ·
Hopefully this resolves your hissing noise, and it might even resolve your random stalls too! it is interesting though, I'll check mine out tomorrow, they look nearly exactly the same as ours on the T5.

Two green connectors angle the same way. a single Y with a middle connector, a hose that connects to the intake tube, and a hose that connects to the intake manifold. The only difference it looks like is yours curls in and goes left into the intake manifold, whereas ours goes straight in. You know if you wanted to save a few bucks you could get some hose barbs from home depot, put them together with a coupler and 1' of that tubing and keep teh rest of it the same but replace that one section...just my 0.02, I'm always looking to save a bit if I can.
 
#27 ·
I agree with you on the saving money piece. I think we might try some way such as the one you mentioned to see if we can seal that up if it is leaking, and if it fixes it then we will just buy the new hose for 113$.
 
#28 ·
Quick update: so I noticed today that when I was parking out front of my house that whenever I'd turn the steering wheel the headlights would dim down significantly.

I have linked a video below that shows this, as whenever the headlights dim the RPMs/engine sound changes as well. I know this is normal, as power steering is a huge energy hog, but should they dim this much?? Hopefully this can lead us in the right direction of our p0101 RPMs/stalling issue if it's not normal.

Link: https://goo.gl/photos/u8FYF4akXnpPvKCBA

Sent from my XT1575 using Tapatalk
 
#30 ·
Okay, that makes me feel better. I just didn't know if it had anything to do with the whole issue we've been having with P0101 code and all. I just want it fixed but finding vacuum leaks is a pain when you can hear them but don't know where they're coming from :'( .
 
#31 ·
Can someone confirm or deny that when you replace the throttle body, it is a simple 'pull the old part out, put the new part in'?

Evy, I have been experiencing idle 'dips' when I stop, and my research so far is indicating that it is the throttle body starting to fail. Check out this information here. Different car, but similar symptoms it sounds like. I do not have any CEL yet, but I will try to read for hidden codes tonight.

I have noticed the dip in RPM's/headlights when turning the wheel when stopped... I won't say its normal but I've had it for the few years I have owned the car (2008 s40 2.4i).
 
#32 ·
From what I've heard from everyone else it is plug and play. Might need to do a battery pull to allow the car to relearn but as long as you get the correct part # it's plug and play. I'd pick up a used one off of eBay for cheap (as long as it has low mileage).

I do still hear in my case what seems to be a vacuum leak, but with my TB having such high mileage on it (118k), it'd make sense. It's also been something that sometimes it stalls, other times it's completely fine and just does the RPM dips.

The other thing as well is sometimes the RPMs go up, but other times the RPMs go down. It's completely random. Sometimes it's both.

The code that I have is P0101. Which in Volvo OBD language, that translates that the MAF sensor has a "flow too low". I'm assuming this is because the TB plate isn't opening as wide as it should be, and then when coming to a stop, the engine "chokes" so to speak, and to try and make up for it, the plate opens up wide, explaining why my RPMs would then increase.

In my case, this all makes sense, but I still believe I hear a vacuum leak coming from the intake manifold. A used TB and the hose that we believe is leaking are roughly the same price, so I'm not sure what we'd do first.

Sent from my XT1575 using Tapatalk
 
#33 ·
The vacuum hose you think is leaking connects down-stream of the MAF correct? Tonight I can listen to my engine under the hood and see if I hear a similar suction noise. Keep in mind, that it might be air pulling around your throttle's butterfly valve, but until I listen to my engine I am just guessing... that sucking noise was pretty loud in your video.

I'm at 105,000 miles, going to try a cleaning this week. I was having a hard time finding TB's that had low miles on them, and I'm sure mine would be categorized as 'running fine' on an ebay ad.
 
#34 ·
The vacuum hose you think is leaking connects down-stream of the MAF correct? Tonight I can listen to my engine under the hood and see if I hear a similar suction noise. Keep in mind, that it might be air pulling around your throttle's butterfly valve, but until I listen to my engine I am just guessing... that sucking noise was pretty loud in your video.

I'm at 105,000 miles, going to try a cleaning this week. I was having a hard time finding TB's that had low miles on them, and I'm sure mine would be categorized as 'running fine' on an ebay ad.
Yeah it's downstream the MAF. The hose I hear leaking is the one that connects to the top of the manifold and has a red ring around it where it connects.

I've cleaned mine as well.

Also, look around for the Porsche throttle body upgrade. It's a direct fit but has a slightly larger opening. I say this because I can find many online with low miles (I saw one with 33k miles for 150$). Even if you don't want to upgrade, it's still lower miles and works better.

Sent from my XT1575 using Tapatalk
 
#35 ·
To my understanding, this link right here is the exact throttle body that goes on our P1 Volvo's (I'd check per year to make sure, its different for every car) but for a 2006 S40 2.4i this is the one: http://www.volvopartswebstore.com/products/Throttle-body/1132404/31216327.html . It should be plug and play, and its a really good price from a known seller. Its brand new, meaning that if it is the issue, ti'll hopefully add another 100k miles or so to the car. My dad and I are seriously just looking at replacing it in my car at this point.
 
#39 ·
Hmm. So this does seem to be the same hissing noise.

Also, another quick update. As I was picking a friend up today I sat out in my car for a minute with the radio off and all just with it sitting in park at idle. As I was sitting, I could noticably hear the engine RPMs being rough. This didn't show very well on the gauge however.

Basically it sounded rough, then the RPMs would drop (by 50RPMs at most) and then surge back up by like 100RPMs, and then come back down to where it was first. When this all happens, you can feel a very strong vibration in the car when it pushes up in RPMs. You can hear it audibly and feel it, as well as see it on the gauge a bit. I took a video to show you, although you can't hear the sounds as the microphone on my phone wasn't all that good.

Here's the link to the video: https://goo.gl/photos/zN1gUWpdSY93EASQ9

Could this "surging" or "hunting" at idle be the throttle body, or is there a chance it could also be a vacuum leak as well?

I feel like it's the TB, but want to make sure it's also not a vacuum leak.

Sent from my XT1575 using Tapatalk
 
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