Technical `Hunting ` revs on tickover . 2007 ,2.3 Ducato

[marcus36]

Hi all , got a wee problem my 2.3 ,2007 Ducato . On tickover , mainly from cold , the tickover is erratic in that the revs keep dropping, as though the engine is `hunting` , fuel maybe.Its less bad when really warmed up . I fitted a new throttle body a couple of years ago and new vacuum pipes to the valve under the scuttle panel .Anyone had a similar experience / Anything obvious / No faults showing on the scanner . TIA

 

[bugsymike]

Hi all , got a wee problem my 2.3 ,2007 Ducato . On tickover , mainly from cold , the tickover is erratic in that the revs keep dropping, as though the engine is `hunting` , fuel maybe.Its less bad when really warmed up . I fitted a new throttle body a couple of years ago and new vacuum pipes to the valve under the scuttle panel .Anyone had a similar experience / Anything obvious / No faults showing on the scanner . TIA

Any air/fuel leaks on the diesel filter line?
Is it worse after standing for a few days?

 

[marcus36]

Hi thanks for your reply . Ive just been reading a similar thread here and will be checking a few things , but the filter is a good call ! ive never liked the plastic push connectors on the fuel lines . I havent noticed wether its worse when its been stood yet

 

[bugsymike]

Hi thanks for your reply . Ive just been reading a similar thread here and will be checking a few things , but the filter is a good call ! ive never liked the plastic push connectors on the fuel lines . I havent noticed wether its worse when its been stood yet

Worth checking , but generally more of a problem where no electric pump in tank and injector pump has a primer at the filter area, so has to suck fuel which is when air getting into fuel system more of a problem.
2.litre Scudos, Dispatches and Experts with Siemens fuel systems prone to it.

 

[linknet]

Hi all , got a wee problem my 2.3 ,2007 Ducato . On tickover , mainly from cold , the tickover is erratic in that the revs keep dropping, as though the engine is `hunting` , fuel maybe.Its less bad when really warmed up . I fitted a new throttle body a couple of years ago and new vacuum pipes to the valve under the scuttle panel .Anyone had a similar experience / Anything obvious / No faults showing on the scanner . TIA

I had that problem of rough idling while cold on my previous 2009 Ducato and it turned out to be the EGR (Exhaust Gas Recirculation) valve sticking. My garage gave it a good clean out, rather than replace it, and it cured the problem.

 

[AsdaPricey]

Hello @marcus36

A couple of things to try….

Fitting in with the experience of @linknet, you could isolate the EGR by plugging both vac lines to the Egr control valve on the scuttle to see if there is any improvement.

A MAF sensor on its way out can produce hunting and will not leave any DTC’s.
Unplugging it will leave a code whilst the ECU will revert to a default fuel map. This would assist in identifying if that sensor is having an effect on the idle.
The MAF is also affected by temperature which could fit in with your normal running once engine is up to temperature…

 

[Communicator]

Is the vehicle a motorhome? Is the problem new or ongoing? If yes then there is a remote possibility of an electrical interaction between the ECU and the motorhome systems.

When my PVC was relatively new, I decided to change the initiation of the automatic step retraction from IGN +, to D+. On starting the engine to test my modification, the idle rpm hunted in an alarming manner. I suspected that a capacitor that is normally fitted across the step relay coil, was interacting with the alternator field circuit in some way. A repeat relay connect in front of the step relay made a temporary fix, but it did not make sense.

My PVC is fitted with a CBE habitation electrical system. CBE do not use conventional D+. Instead the system monitors an IGN+ connection, which is used as a simulated D+ over 13.2V. Later investigation revealed that the converter had incorrectly connected the CBE IGN+ to the actual D+. This connection was hidden between the starter battery, and the bulkhead on the x244 base vehicle. Not immediately obvious. Diverting the connection to a spare IGN+ fuse allowed eventual removal of the temporary relay without any hunting problems.