Intermittent idle

[dioliahary]

Ford Custom Ecoblue. 90k, 2019.

Injectors replaced this month, wet belt changed 3k miles ago.

Will idle at 750 rpm, but every now and then when idling, engine starts to hunt with erratic idling up and down, this occasionally escalates into disturbing engine vibration, noisy, clunk from engine, very disturbing forcing engine shut down which normally resolves the problem and idle returns to smooth, normal operation.

If I keep the idle at 1000 rpm, no problem.

Had the injectors changed due to service message, obd showed injector two faulty. Recently took to Switzerland with no issues. I had the injectors changed due to these symptons. No service message presented since injectors changed but idle problem still exists.

Thinking dirty EGR valve?

[metalworker0]

You could dismantle the EGR and find out , this is a task that should be done often, perhaps every service or every other service, depends how you drive . you are looking at removing built up gunge and carbon.

But, what they recommend here is you plug in a code scanner , then you find out if the EGR is stuck or sticking open, or any other problems Causing this.


Forscan - that's what they recommend here . you may get more info from this

NOTE: you can use forscan to get correct fault codes with proper explanation of them - a generic fault code reader may be somewhat misleading, or doesn't work

"Forscan" is FREE software that you download to a laptop..you buy the interface cable -- this is just the cable, you need a laptop)
You can join the forscan forum ..again free, to get the software and more answers.

https://forscan.org/forum/

Then you come here list the fault codes here ..and we will try to work out the problem.

all the best.mark

[dioliahary]

Thank you, a great reply. Forscan lead ordered and will keep you updated.

[dioliahary]

Further info, I really should have noted in the first post, no error codes presenting.

I will still get the Forscan software and lead as sounds like a fab bit of advice.

[metalworker0]

Error codes will not present themselves .. when in open loop ... that's from start up to reaching normal temperature and at brisk acceleration.
idle speed is supposed to be 850RPM

Things that can effect idle speed and smooth operation .

Antistall
There are devices that add more idle speed in normal use like a switch on the clutch senses when the clutch is depressed - this increases idle as it's used .. this is an anti-stall feature.
Traction control
As well, there are other features on the van you can turn on or off like traction control that may be playing up .. especially since you said knock ... the traction control uses the brakes to limit wheel slip .. a fault with the brakes this may lead to that brake sticking and the brakes and traction control not working in harmony with each other .

Hill start assist note - copied from AI .. as i don't want to be typing when this is already described here better than i could do .

Hill Start Assist automatically holds your vehicle in place on a slope for a few seconds after you take your foot off the brake, giving you time to move to the accelerator and move off without rolling backward or forward. The system uses sensors to detect the incline, then maintains brake pressure until it senses you're applying the accelerator, at which point the brakes release. It is a standard feature in most modern cars and requires no driver input to activate, other than the usual process of coming to a complete stop on a hill.

all these system rely on good brake and fully functioning ABS sensors .. a stuck brake when using this feature would cause a knock as its released.

EGR stuck / open faults and boost faults from holes, leaks, boost pipes or faulty turbo actuator can usually be shown up forscan .

NOTE .. like many here i'm forever learning about these systems, i'm not a diagnostic technician and i don't know everything .


all the best.mark

[dioliahary]

Thank you.

[dioliahary]

Bit of an update, ran the van down the motorway (dpf was at 35%). Ragged it and the dpf went to 100%?

Induced a forced regen via dash, 20 mins at 2000rpm.

Dpf cleaned to 5%, but then the rough idle returned, sounds lumpy and a bit of engine vibration after the regen.

Up till the forced regen, it sounded like a sewing machine.

Slowly settling back down to sewing machine sound again now.

[metalworker0]

Depends on your interpretation of a sewing machine , usually that statement means, it runs smooth and precisely.

all the best.mark.

[dioliahary]

Yes, sewing machine sounding normal. So just checked it again and a steady quiet 800 rpm.

I am beginning to think that this maybe connected to the dpf regeneration.

I think the rpm spikes may well be the anti stall kicking in.

Probably comes down to me doing average 6 miles per day.

Not sure, still not ruled out egr valve yet.

Downloaded Forscan and will buy a lead and see what readings I get when it happens again.

[metalworker0]

When in DPF regeneration mode - "unforced" .. it spikes the rpm, and does a whole load of other things, it switches on heated mirrors .. it switches on heated screen, it switches on the radiator fans, it alters the fuel injection timing. so that the engine is put under load runs hotter to help with regeneration.
And, umm you are meant to dismantle the EGR on a regular basis to keep these engines running smoothly, this is something they don't tell you about in the sales literature or the owners manual ... if a service of the EGR is not done, then eventually it will stop working ... and worse case scenario .. breaks gears in the actuator or the EGR motor burns out. because its jammed. that time period is determined by your use .. town driving could will mean it has to be done every 15,000 miles .... or motorway driving may mean it only has to be done every 30,000 miles. this is what these gadgets do to modern diesels .. they just cause more problems.

all the best.mark