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Help with V50 2.4i bad idle and stalling

13K views 78 replies 11 participants last post by  johnaau 
#1 · (Edited)
Help with V50 2.4i bad idle and stalling only when warmed up

I just bought myself an August 2006 manufactured V50 with 2.4 petrol engine (B5244S4), knowing that it had a few problems.

After I bought it, on the 1-hour drive home, once it gets warm (drive for 15 minutes or more) the idle starts fluctuating and it will usually almost stall and often stall. It seems to drive well when it is not idling.

I got it home and found the top of the engine to PCV hose was broken in several places so replaced that, hoping that was the problem. The codes had been cleared due to disconnected battery before I had a chance to read them.

Took it for a 15-minute test drive and it seemed okay but reported a P0190 fuel pressure sensor fault.

The next day I drove it a bit longer and after a 15 minutes, it started idling low and nearly stalling, same as before. I was watching the fuel pressure on Torque OBD scanner and it was consistently high to mid-50 psi. When I got home I checked and cleared the codes again (P0190) but the idle was now different - it was idling high and fluctuating up and down higher around 1,000 rpm and not stalling.

I took a photo of some of the charts I was watching on Torque (see below). You can see how vacuum, throttle and MAF all cycle up and down with the engine idling.

I'm guessing I need a fuel pressure sensor, but I'm not convinced that is part of the idle/stalling problem as I'm assuming that once the check engine light comes on it is going into some failsafe mode.

I am suspicious of the throttle chart cycling up and down but don't know if that is the cause of the issue, or a result of the issue. But I don't know what Torque is displaying for throttle (actual? expected?).

Anybody had a similar problem that might be able to offer some advice? I'm trying to fix myself at this stage (with help from the Internet). Can a FPS cause this idle/stalling issue? Any advice on how to diagnose further? Other possibilities: ETM? MAF? PCV system? Other?

Oh, and I've also got an anti-skid error - can codes for these be read with any generic OBD scanner or is that a VIDA only thing?

 
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#41 ·
Im still with the PCV BREATHER. You can get a kit at FCP and if it fails theyll replace it for cost of shipping. The diaphragm inside could be causing a vacuum leak situation. Once the air box is out-it should be like an hour to an hour and a half job.


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#43 ·
Definitely want to check terminals and grounds.


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#45 ·
Very very strange. Anything is possible but without diagnostics it's all guesses.

Wheel sensors can be flaky but generally not when the car is stationary. Anti-skid disabled can be caused by this but again, not when starting at 0mph.

Does it die if the car is in D or R, instead of P or N? Maybe the transmission is sending something strange.

Really, VIDA or a pro tool is needed here.
 
#47 ·
Highly unlikely to be the CEM, in the absence of other symptoms. No significant engine control happens there.

It is however a termination point for the high-speed CAN bus, which links the ECM and BCM. But look to those first (i.e. fix one thing at a time).
 
#48 ·
I'm still waiting on my DICE from China but had an opportunity to try a different OBD scanner.

I was watching all the throttle position values when the problem was happening (idle down and up and sometimes stalling). The throttle pedal position values stayed constant all the time (rules out pedal position sensor?). The TAC_PCT value (which if I understand correct is the position the ECU is commanding) goes up and down with the idle, and so do all of the other TP values (TP, TP_R, TP_B). To me this looks like the ECU is reacting to the near stall and commanding the ETM to open to prevent stalling. This makes me think that the ETM is probably ok and the cause is something else.

I also watched the EVAP_PCT and it did not change before/after the problem started so that might indicate it is not an EVAP issue.

When the idle is fluctuating I did notice on this OBD scanner that the SPARKADV is fluctuating significantly between positive and negative values. Again, I'm not sure if this is the cause or result of the problem or is any help at all. Many other values also fluctuate with the revs so I have no idea.

So basically I am no closer to fixing this problem and still hoping that VIDA will have all the answers... Unless of any of the above indicates something to someone?
 
#49 ·
I’m not familiar with any of the scanners except VIDA. It goes into extreme detail and can usually tell you the problem down to what to replace directly. There’s only a few instances where you have to know cause > effect.
 
#50 ·
This sounds like my car's behavior with the bad MAF.
Idle would jump around a little, car wouldn't act or behave normally, die at startup, low 500rpm idle and die, and so on. - it took almost 2 or 3 months of daily driving to flick me a specific MAF sensor too low signal code, everything else was generic P0101.

Oddly enough, I recently unplugged my MAF when the car was misbehaving after a car wash, and the car ran perfectly, I mean, went from misfire every time to absolutely flawless start and idle and full throttle.

My suggestion - unplug your maf, get in and then turn on and start your car, if your idle is smooth and good that might be the problem, however unlikely it is.
 
#52 ·
Well, after waiting a month (or was it two?) for my DICE clone to come from China so I could check codes in VIDA it finally arrived and after some effort in getting it to work I don't really have any useful information.

There were a few errors as expected, and the only ECM codes were ignition coil and misfire. After clearing the codes none of them returned except CCM-0071 (climate control system).

BCM-0101 Communication between control units communications problems with ECM
CCM-0071 Damper position (TP) faulty position
ECM-3200 Ignition coil - faulty signal
ECM-3502 Misfire, emission related - multiple cylinders
CCM-0076 Damper motor temperature left internal fault
DDM-8022 Side turn signal indicator open circuit or shorted to supply
CCM-0009 Fan motor passenger compartment temperature sensor blocked
CEM-DF11 CAN-H high speed network signal missing
DDM-DD11 Communication with switch pack internal fault
ECM-2110 Front heated oxygen sensor (HO2S) - Signal too low (MY FAULT - I DISCONNECTED IT DURING TESTING)
CCM-DD14 Damper motor no communication

I let the car run for some time with the idle problem present and near stalling but no new codes showed up.

I don't know what to do next. I'm leaning towards taking it to a Volvo dealer or specialist although I'm worried they will just throw parts at it until it is fixed (at my expense).

Also what temperature should the fan kick in? I saw temps in VIDA of over 105 degrees Celcius and the fan never came on. When I manually activated the fan using VIDA it worked fine.
 
#53 ·
Update to this thread: after my last testing with VIDA I found a radiator hose had split and lost a bit of coolant so had to order a new hose and have just fitted it today. At the same time I fitted new spark plugs because I finally got around to checking them and they looked pretty tired.

So I ran the car again today and it ran better - still idled badly when hot, but less likely to stall. A friend working on it with me said that might be a sign of a bad coil - that it improved a bit with new plugs. I did run it again an hour or two later and it was stalling more like usual though so as usual not very conclusive.

I still find it real strange that it won't idle properly and will stall at idle, but if I roll down a hill in neutral it will sit there at ~800rpm same as when idling and run perfectly. Wonder what is different about a stationery idle and a moving idle?

I plugged it back into VIDA and I now have ECM-3502 Misfire emission related multiple cylinders. It's on the delivery tab and the initial state tab. Based on what's in VIDA about this fault code, there is quite a few things to check.
 
#54 ·
The coil idea is plausible but there are 5 coils and that would not explain a multi-cylinder issue. You can easily test however, by swapping them between cylinders to see if a problem moves with them.

Yes, ECM-3502 is a long list. Be methodical.
 
#55 ·
Will this thread ever end?

I'm sure I checked for misfires last time, but I checked live data in VIDA and I get misfires on all cylinders only when the idle problem is occurring. Video follows.


(video shows it idling on its own first, then me revving it a little and trying to hold it around 900pm, then letting it try and idle itself again)

The misfires seem to be worse on cylinders 2, 3 and 4.

I swapped coils 3 to 1 and 4 to 5 and the misfires did not move, they were still worse on 3 and 4.

The most frustrating part of this problem is that when I research all the possible problems there is one thing that does not make sense: why will the car will fail at idle but it will run fine at a similar speed to idle if I lightly hold the throttle pedal or when the car is rolling in neutral?

Possibilities like faulty coils, low compression, intake leaks, blocked PCV, various sensors, leaking valves... they just don't make sense to me.
 
#56 ·
Focus on fuel. Are you absolutely certain the pressure sensor is good?
 
#57 ·
To me that looks like your injectors are leaking. Putting out too much at idle causes the misfires, but add a little RPM and it whips that extra fuel into the chamber and burns it no problem....
I don't think it is coils since performance worsens when hot, and you moved them.
It might be plugs given that the middle 3 are the hottest but that is low probability if they function good under normal WOT.

Also idling down a hill means that your RPMs don't drop to idle, but iirc looking at my tach it was something like 800rpm, above the 720 or 750 our cars normally truly idle at...could be wrong on this tho.
 
#58 ·
I previously had a code for faulty fuel pressure sensors and have since replaced it with a new Bosch sensor with the same part number. The fuel pressure reported in VIDA is showing as normal and is consistent (doesn't fluctuate when the idle problem is happening).

I'll start researching how to check for leaking fuel injectors.
 
#59 ·
I have done some research on leaky fuel injectors and they do seem a good possibility. Although idle issues only when hot doesn't seem to be common but hot start problems do, but my car starts fine when hot.

It also seems I should be seeing negative short term and long term fuel trims. My fuel trims are very constant around zero and don't fluctuate with the problem from what I can see.

Oil contaminated with fuel is supposedly another sign but I can't smell any in my oil.

Injectors still seems like a good suspect - partly because they seem to be known to be more problematic in the middle hotter cylinders - but not sure what DIY testing I can do.
 
#60 ·
I hope I'm not speaking too soon but I think I may have found the cause of my idle/stalling problem.

I was suspecting fuel injectors because I read that they often go bad in the middle/hotter cylinders (which is where my misfires were) so I was thinking how I could test them. I decided to see what would happen if I waited until the problem happenned and then ran a garden hose over the injectors and rail to cool it down.

I tried that and there was no change but I thought I should also try cooling down other components so I ran the hose over the throttle body, coolant sensor, any any other sensor I could find. Still no change.

I had pretty much given up when I thought to see if I could reach the crank sensor. I sprayed it with water and the problem stopped. The car got hot again and started idling bad and stalling and I sprayed it again and the problem stopped. I found if I prodded the sensor and connector with a long screwdriver I could start and stop the problem.

So I pulled apart intake, airbox, and various parts of the wiring so I could reach the sensor and I see that the crank sensor connector is broken and kind of held on with a cable tie. I suspect just a wiring issue so I clean the connector and use a larger cable tie to hold it together. Put it all back together and take it for a test drive and unfortunately it is still stalling but cold water again makes it run right. So the next step is to get a new crank sensor and maybe a new connector to be spliced in and see if that solves the problem once and for all - I'm confident it will.
 
#61 ·
Good sleuthing! It's not a common issue on these cars, but it certainly would cause these types of symptoms.

What caused it to break, do you think?
 
#62 · (Edited)
I'm going to get a replacement sensor today from a junkyard (quicker than waiting for a new one to arrive, and they don't appear to be a common failure item so should be okay) so will get the old one out and have a look for a possible cause. Someone has been in there before and broken the connector, and I also noticed the temperature sensor connector is broken. I will try and get the plugs from the junkyard at the same time.

What I find strange/annoying is that the ECU is not detecting a fault with the crank sensor. It is meant to be something that can be diagnosed by the ECU according to Volvo's documentation in VIDA, and surely it can't be difficult for the ECU to compare crank and cam sensor readings and realise something is wrong?
 
#63 ·
Our ECU's have a historical precedent for most of us that indicates everything around the problem not working right, but never indicating the problem itself.
 
#64 ·
I put in a new (used) sensor and the car ran fine on a few test drives. I was confident the problem was solved. But then it started happening again :(

I couldn't see any physical damage to the old sensor, but the plug on the wiring harness had broken and was being held on with a cable tie. I'm going to try a new plug.
 
#65 ·
Bummer. I suggest going back to the junkyard and cutting off the plug. Then splice it into the wires of yours. Use solder and shrinkwrap.
 
#66 ·
Update: I replaced the plug and it made no difference.

I can get the car up to a temperature where the problem happens and then spray the crank sensor area with water and it the problem goes away for a short time until the water dries up. Not sure if I am cooling it down or affecting an electrical connection. This test is a little inconsistent, most of the time the water will stop the problem but not always, so I am second guessing my diagnosis now.

One thing I noticed during this testing was that I could influence the problem by removing and then reinserting the dipstick or oil cap, so I am now suspecting PCV/oil trap (again). Even if I run the water over the crank sensor if I remove and then reinsert the dipstick the problem usually happens again straight away.

Is it likely that the PCV would only affect the engine when hot?

I have vacuum at all times (problem happening/not happening) idle according to the rubber glove test so I thought my PCV was ok. The idle/stalling problem still happens with the dipstick in or out, I just seem to be able to induce the problem by doing this.
 
#68 ·
Is it likely that the PCV would only affect the engine when hot?
Does your PCV have an electrical connection? It's hard to see, because it's at the top of the unit behind the airbox. The connection shares a circuit with several other functions, and issues with the element have been known to have strange effects.

The car will be fine with it disconnected, if you can get in there to release the clip and pop the connector, it's maybe worth a try.

OTOH, not all vehicles have it.
 
#69 · (Edited)
There's no seal. The sensor is on the flywheel so I don't think there's any vacuum source nearby. But I will investigate further.

Does your PCV have an electrical connection? It's hard to see, because it's at the top of the unit behind the airbox. The connection shares a circuit with several other functions, and issues with the element have been known to have strange effects.

The car will be fine with it disconnected, if you can get in there to release the clip and pop the connector, it's maybe worth a try.

OTOH, not all vehicles have it.
It does. I will remove it and give it a try.
 
#71 ·
I did try disconnecting the electrical connection to the PCV but it made no difference.

I can't see how enough water would be getting down to the rear my seal and staying there to make the car run well for a minute once the water is stopped. But I guess it is a possibility.

I bought a used throttle body to try but that made no difference.

I had another look at the crank sensor that came out and there is a small mark on it, possibly from contact. I am thinking maybe to lift it slightly with a washer or something in case something is expanding when hot, or maybe trying another sensor.
 
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