Hi

I have an 07 x250 2.3 130hp multijet which has developed an intermiitent hesitation/misfire and slightly erratic idle!

Initially a scan gave 3 errors to the lambda sensor, changed that but problem persists. Researched on here and changed the egr valve, the egr valve solenoid and the throttle body.

No lights illuminated on instrument cluster, pulling the connector off the mass airflow sensor it idles better but not perfect. Also I pulled the vacuum hose of the egr solenoid and again better idle.

Checking the egr valve on multiecu scan reveals that the valve is continually cycling open/closed whilst engine is running ie being driven and whilst it is idling!

Only remaining components to change are th maf sensor, fuel and air filters and pressure regulator or injectors.

Fuel pressure at idle is about 350 bar

Any thoughts please?

Phil

Harbottle said:

Hi

Checking the egr valve on multiecu scan reveals that the valve is continually cycling open/closed whilst engine is running ie being driven and whilst it is idling!

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If the egr valve is really cycling whilst idling the ecu has gone crazy. It should only allow the valve to open while coasting at or above 2200 rpm, not at idle and not while accelerating.

CDK said:

If the egr valve is really cycling whilst idling the ecu has gone crazy. It should only allow the valve to open while coasting at or above 2200 rpm, not at idle and not while accelerating.

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Yes, that's what I was thinking, but why? I don't want to have to fork out for an ecu repair or replace!!

I understand your reluctance, but you may have no other choice unless you blank the egr valve.
There has been written a lot about it on this forum. My own solution has been to cut the vacuum hose, insert a piece of solid metal and connect the ends again so nobody can see what you've done.

As an update still having the same problem after now changing the maf sensor, fuel pressure regulator, and an injector bleed down test.

Next I suppose is check the wiring to ecu and in the loom under t6he left headlamp!!

Any other suggestions please?

I had the same probs as you and after spending a fortune changing loads of parts I sent my ecu to the ecu doctor in Plymouth who told me the ecu was faulty they repaired it and after refitting it I've had no probs since try giving them a call it might help you, google the ecu doctor

Might be worth checking the suction control valve.

Ducatiman said:

Might be worth checking the suction control valve.

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If you mean the fuel pressure regulator? Then yes already changed! Only thing left is ecu or wiring to it methinks!

Harbottle said:

If you mean the fuel pressure regulator? Then yes already changed! Only thing left is ecu or wiring to it methinks!

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It regulates fuel flow from the low pressure pump into the high pressure injection pump, had one go bad in my Nissan Pathfinder recently and gave similar symptoms to the ones you described.

Further update! Still have same rough idle and slight misfire. Have found that egr valve is open on idle! I've already changed the egr solenoid and egr valve.
In fact egr valve is being signalled to be open at all times and pulses closed frequently.

Checked ecu connectors and they are nice and clean.

Scanned a mates van and the egr valve on that is closed at idle and opens at higher throttle openings!
Throttle body changed along with fuel filter, maf sensor and fuel pressure regulator. Injector leak test ok

Any suggesttions where to go next?

Harbottle said:

Any suggesttions where to go next?

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I think you've already had good suggestions, blank the egr or send the ecu for testing / repair. ECU Doctor is only £35 to test and diagnose, you've already spent a fortune changing perfectly good parts.

I fear you are correct! Am away at the moment so will send ecu off for testing next week when I'm back.

Checked wiring loom from ECU?
Leads to lots of different issues

Check out my recent thread X250 money saving tip

Wiring to be checked is next on the list! Been away for a while so will be able to check it out soon.