Help with a light misfire on a 2.5T
Discussion
OK, I'll admit up front that I'm asking for help on a Volvo engine not in a Volvo car!
Our S-Max 2.5T hesitates at light throttle.
She idles smoothly and the CO is ok at idle.
Pulls like a train at mid/full throttle.
She hesitates slightly at light throttle from 2000-3000rpm - for example if you're in 5th or 6th at a steady 60 or 70mph.
The only fault code that has shown up (checked by a Ford dealer) is PO61A - PCM Torque Performance. Nothing else showed up when they plugged in the diagnostic check.
Spark plugs are new.
The only work that's been done recently is a new boost control solenoid.
Would be really grateful for any help!
Nick
Our S-Max 2.5T hesitates at light throttle.
She idles smoothly and the CO is ok at idle.
Pulls like a train at mid/full throttle.
She hesitates slightly at light throttle from 2000-3000rpm - for example if you're in 5th or 6th at a steady 60 or 70mph.
The only fault code that has shown up (checked by a Ford dealer) is PO61A - PCM Torque Performance. Nothing else showed up when they plugged in the diagnostic check.
Spark plugs are new.
The only work that's been done recently is a new boost control solenoid.
Would be really grateful for any help!
Nick
We tried all manner of things...
In the end we got a mobile diagnostics tech to look at the car (it's a long story but the local Ford dealer had a huff when we used them for a diagnosis once and didn't give them the repair work).
Mobile tech wasn't very good but be did at least identify that the fuelling correction was at max lean at those revs and low load. After lots of guesswork he suggested a new wideband lambda sensor.
I think this has improved things but the car's still a little hesitant at very light throttle, but that might just be a characteristic of the engine.
Was yours always smooth at that point and has just started doing it?
Ours started after having the boost control solenoid replaced but the tech couldn't find any intake system leaks afterwards.
Be very interested in whether you find a cause for yours.
Nick
In the end we got a mobile diagnostics tech to look at the car (it's a long story but the local Ford dealer had a huff when we used them for a diagnosis once and didn't give them the repair work).
Mobile tech wasn't very good but be did at least identify that the fuelling correction was at max lean at those revs and low load. After lots of guesswork he suggested a new wideband lambda sensor.
I think this has improved things but the car's still a little hesitant at very light throttle, but that might just be a characteristic of the engine.
Was yours always smooth at that point and has just started doing it?
Ours started after having the boost control solenoid replaced but the tech couldn't find any intake system leaks afterwards.
Be very interested in whether you find a cause for yours.
Nick
Since ford messed about with the engine since pinching it from volvo 
It's hard to suggest much but I'd be looking at the fuel pressure regulator (if it has the one on the fuel rail itself, fit the equivalent landrover part as it's half the price)also make sure the BCS is plumbed - in correctly and that all the vac hoses are fitted properly and in good shape. If it's happened since fitting a new bcs, I'd start there and work outward - anything nearby been disturbed?
There's also the possibility that the engine is supposed to run this way and the difference you had prior to the fitting of the new bcs was a sign of a fault with the old one.
Stick a IPD bcs on there, that'll liven it up a bit
It's hard to suggest much but I'd be looking at the fuel pressure regulator (if it has the one on the fuel rail itself, fit the equivalent landrover part as it's half the price)also make sure the BCS is plumbed - in correctly and that all the vac hoses are fitted properly and in good shape. If it's happened since fitting a new bcs, I'd start there and work outward - anything nearby been disturbed?There's also the possibility that the engine is supposed to run this way and the difference you had prior to the fitting of the new bcs was a sign of a fault with the old one.
Stick a IPD bcs on there, that'll liven it up a bit
martinrpeachey said:
Since ford messed about with the engine since pinching it from volvo It's hard to suggest much but I'd be looking at the fuel pressure regulator (if it has the one on the fuel rail itself, fit the equivalent landrover part as it's half the price)also make sure the BCS is plumbed - in correctly and that all the vac hoses are fitted properly and in good shape. If it's happened since fitting a new bcs, I'd start there and work outward - anything nearby been disturbed?
There's also the possibility that the engine is supposed to run this way and the difference you had prior to the fitting of the new bcs was a sign of a fault with the old one.
Stick a IPD bcs on there, that'll liven it up a bit
It would have been hard to sense anything as subtle as a minor hesitation before - first the BCS was a bit sticky (acceleration tended to come and go in waves as the BCS tried to control boost) then the BCS finally stuck open leading to overtorque... It's hard to suggest much but I'd be looking at the fuel pressure regulator (if it has the one on the fuel rail itself, fit the equivalent landrover part as it's half the price)also make sure the BCS is plumbed - in correctly and that all the vac hoses are fitted properly and in good shape. If it's happened since fitting a new bcs, I'd start there and work outward - anything nearby been disturbed?There's also the possibility that the engine is supposed to run this way and the difference you had prior to the fitting of the new bcs was a sign of a fault with the old one.
Stick a IPD bcs on there, that'll liven it up a bit
The tech who looked at the car checked fuel rail pressure and said it was ok.
Given that he also said he thought it was an EGR problem (not fitted on this engine?) and then a turbo variable geometry vane problem (also not fitted?) I'm not sure how much I'd trust him.
Sounds like he was reading generic codes without having the model specific codes at hand. What comes up on one car as a cooling fan problem can mean ECU failure on another. I don't suppose you have a list of the codes he pulled from the car do you?
a VTG code could be a overboost warning (incorrectly fitted bcs)or signify a minor vacuum leak. Hard to tell without model specific codes really.
a VTG code could be a overboost warning (incorrectly fitted bcs)or signify a minor vacuum leak. Hard to tell without model specific codes really.
martinrpeachey said:
Sounds like he was reading generic codes without having the model specific codes at hand. What comes up on one car as a cooling fan problem can mean ECU failure on another. I don't suppose you have a list of the codes he pulled from the car do you?
a VTG code could be a overboost warning (incorrectly fitted bcs)or signify a minor vacuum leak. Hard to tell without model specific codes really.
He was more sophisticated than that - he was looking at the fuel trim live while running the car, plus a whole load of other ECU outputs.a VTG code could be a overboost warning (incorrectly fitted bcs)or signify a minor vacuum leak. Hard to tell without model specific codes really.
We never got any sensible fault codes logged during the whole time - just the overboost code from a lot earlier and the PO61A - PCM Torque Performance code.
Have a look at this...
http://www.google.co.uk/url?sa=t&rct=j&q=&...
It'll bring up a document that says this code requires the PCM to be reprogrammed. Again sounds like he was reading generic codes as that code is a torque fault on chrystlers and GMs etc.
Could be a light at the end of the tunnel
I checked the code in the Volvo lists and the closest I got was a ROM write fail in the ecu.
http://www.google.co.uk/url?sa=t&rct=j&q=&...
It'll bring up a document that says this code requires the PCM to be reprogrammed. Again sounds like he was reading generic codes as that code is a torque fault on chrystlers and GMs etc.
Could be a light at the end of the tunnel
I checked the code in the Volvo lists and the closest I got was a ROM write fail in the ecu.
NDT said:
thanks Martin.
The really spurious thing was the mobile diagnostic guy who really didn't have a robust and rigorous approach to faultfinding. Very annoying!
Thing is, these cars can throw codes that don't have anything to do with the actual fault. Unless you know the cars and their foibles, you can end up working blind.The really spurious thing was the mobile diagnostic guy who really didn't have a robust and rigorous approach to faultfinding. Very annoying!
Another good code thrown by the MAF is throttle pedal position sensor. Makes no sense unless you know the cars.
I have the same car and a similar problem. Have taken it to Ford 4 times. They originally thought it could be ironed out during a service. No difference. After fault code diagnosis at their side, they then replaced the turbo boost switch. No difference. 3rd attempt was a MAF sensor cleanup and they confirmed that the sensor needs to be replaced. They carrried out the work and still, no difference. 2 things I find are shocking - number 1 they do not appear to be testing the car after supposedly fixing (this could be because the issue is more prevalent when the car is cold / when it's wet). 2nd thing is the patronising attitude of the less than helpful service staff. My wife was talked down to on our 3rd visit and simply asked would this now fix it - the service assistant said with a deadpan expression - 'of course it will, our chief mechanic looked at it'. Well, you were WRONG on that one chum. From reading various forums the coil pack is the most likely culprit - I don't know if they've checked this but I find this particular (unnamed) ford service centre an absolute joke.
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