Mk 7 Surging at idle

[waerhy]

Lived with it for a while now but its starting to do my head in a bit. The van Starts first flick every time and runs faultless when driving, but 90% of the time at idle hot or cold the revs surge up and down slightly. Sometimes it levels out when you lift off the clutch out of gear sometimes not.

60 plate FWD 2.2 tdci

[Altransit]

If it does it when the clutch is down, that will be the anti-stall software faffing about. I think it's fairly common, but not sure if it's fixable

Or it's this viewtopic.php?f=40&t=73368

[knobby1]

Lived with it for a while now but its starting to do my head in a bit. The van Starts first flick every time and runs faultless when driving, but 90% of the time at idle hot or cold the revs surge up and down slightly. Sometimes it levels out when you lift off the clutch out of gear sometimes not.

60 plate FWD 2.2 tdci

Could also be a poorly SCV.

Lord Knobrot

[waerhy]

If it does it when the clutch is down, that will be the anti-stall software faffing about. I think it's fairly common, but not sure if it's fixable

Or it's this viewtopic.php?f=40&t=73368

It does it with the clutch out too.

[waerhy]

The van is has also started to miss fire when starting from cold and at idle. It drives fine though when I pull away, only seems to do it a idle. Been reading up on PSV and SVC being a common problem, would this be a good starting point to get changed out?

[waerhy]

Update on this. I did a pump and injector learn through Forscan which cured the van for about 4 days, so I decided to fit a new PRV and SCV (Denso ones). The SCV went on no bother but the PRV is pouring fuel out when I start the van. Does it have to be stupidly tight or PTFE tape on the threads? the one that came out had no PTFE on it so I thought against it. The picture is of the new one, I put the old one back in and no leaks at all

processed.jpeg

[knobby1]

Update on this. I did a pump and injector learn through Forscan which cured the van for about 4 days, so I decided to fit a new PRV and SCV (Denso ones). The SCV went on no bother but the PRV is pouring fuel out when I start the van. Does it have to be stupidly tight or PTFE tape on the threads? the one that came out had no PTFE on it so I thought against it. The picture is of the new one, I put the old one back in and no leaks at all

processed.jpeg

Yes, they're done up to a silly torque, 172nm or ~126lbft, definitely no PTFE tape, pieces of it could fall off and get into the injection system. What sealing washer is fitted to it.?? The sealing washer, (Ford call it a gasket), can get stuck inside. They usually have a thin sealing washer, the cheaper aftermarket/eBay valves often have a thicker crush washer.

Lord Knobrot

[waerhy]

Update on this. I did a pump and injector learn through Forscan which cured the van for about 4 days, so I decided to fit a new PRV and SCV (Denso ones). The SCV went on no bother but the PRV is pouring fuel out when I start the van. Does it have to be stupidly tight or PTFE tape on the threads? the one that came out had no PTFE on it so I thought against it. The picture is of the new one, I put the old one back in and no leaks at all

processed.jpeg

Yes, they're done up to a silly torque, 172nm or ~126lbft, definitely no PTFE tape, pieces of it could fall off and get into the injection system. What sealing washer is fitted to it.?? The sealing washer, (Ford call it a gasket), can get stuck inside. They usually have a thin sealing washer, the cheaper aftermarket/eBay valves often have a thicker crush washer.

Lord Knobrot

Sealing washer? there were 2 washers in the box but they were on the banjo fitting end

[knobby1]

Sealing washer? there were 2 washers in the box but they were on the banjo fitting end

There will/should be a sealing washer inside the fuel rail where the valve screws in. Best you check to see if the old one is still stuck in there..!

Lord Knobrot

[waerhy]

processed (1).jpeg

Not had a chance to take the old one off, but this is all I got in the box. there was no sealing washer for the large threaded end that fits inside the rail. Is it an o ring?

[knobby1]

processed (1).jpeg

Not had a chance to take the old one off, but this is all I got in the box. there was no sealing washer for the large threaded end that fits inside the rail. Is it an o ring?

Not an O-ring...there's the best part of 1600bar, (23,200psi) in there at full noise, no O-ring is gunna hold that..

Lord Knobrot

[waerhy]

processed (1).jpeg

Not had a chance to take the old one off, but this is all I got in the box. there was no sealing washer for the large threaded end that fits inside the rail. Is it an o ring?

Not an O-ring...there's the best part of 1600bar, (23,200psi) in there at full noise, no O-ring is gunna hold that..

Lord Knobrot

So I'm missing a seal of some sort? any idea what?

Also just found this manual

https://workshop-manuals.com/ford/trans ... tdci_(puma)_diesel/description_and_operation/diagnosis_and_testing/general_procedures/removal_and_installation/fuel_pressure_relief_valve/

[waerhy]

any idea where I can get a new sealing washer from?

[knobby1]

any idea where I can get a new sealing washer from?

Is the old one not still stuck in the fuel rail..??

Lord Knobrot

[Brettbear63]

my van had the same surging problem , I changed my Air filter and it stopped , I think that as it couldnt breathe properly it was struggling at tickover