Technical Erratic idle 2017 1.3 multi jet

[Chaff]

Morning,

I have a Doblo LWB 1.3 diesel. It idles erratically round 1000rpm, sometimes it feels like the engine lurches, very occasionally it will surges when driving. Most of the time drives fine plenty of power etc etc.
on shutdown a squeak (like a pressure bleeding off) is heard from the engine bay, not sure if related.
so far I have changed the fuel filter, cleaned the MAF (readings seem ok) checked the Vac system couldn’t find any leaks. No codes when I plug into MULTIECUscan.

Not sure if anyone else has had these problems or anything similar?

Many thanks
Chris

 

[Abarthmultijet]

The pressure bleed off and squeak is normal.

There is a throttle body just before the inlet manifold, when you unplug it, does the strange idle stop?

 

[Chaff]

Abrathmultijet, the van is in getting an MOT when it comes back I will give that a try. Thank you for your help.

 

[Chaff]

Finally got around to testing the van. Had to change the 2 front srpings for the MOT. I disconnected the throttle body and is sounded better. Less lumpy, I tried to display the export from Multi ECU, Computers are not my thing. Haha. From what i can make out the "throttle Vv open" is bouncing about from 8 - 25% where as the target and actual are all around 0.32%. What are your thoughts, Throttle body issue or else where?

 

[Abarthmultijet]

It is not a bad thing to remove the Throttle body and clean it. Usually it is full of soot. Make sure the butterfly valve reaches both ends. (max and min position)

Removal is quite simple, 2 torx bolts holding on the hard plastic boost pipe and I believe a 10 mil bolt holding that pipe to an bracket above the gearbox. 3 torx bolts holding the throttle body to the inlet manifold. Then an allen key bolt for the bracket of the throttle body. The upper torx bolt holding the throttle body looks difficult to remove, but there is a hole in the throttle body front where your tool can fit through.

 

[Chaff]

Hi thank you again for replying.
Removed the throttle body and give it a good clean, seemed ok, slight amount of carbon. Moved through the full range easily enough. Still sounded erratic when I replaced it. I done another Quick check for a Vac leak couldn't find anything though. Thinking of doing an injector clean?

 

[The Panda Nut]

It sounds like it may be sucking air. Check the diesel filter is tight. Apply vaselene to all pipe joints and the filter head . One at a time. If it settles you have found the leak at the last one treated. Check the water drain is tight and not cracked too.

 

[Abarthmultijet]

Hi thank you again for replying.
Removed the throttle body and give it a good clean, seemed ok, slight amount of carbon. Moved through the full range easily enough. Still sounded erratic when I replaced it. I done another Quick check for a Vac leak couldn't find anything though. Thinking of doing an injector clean?

Not very good experiences with diesel injector cleaners, might work for a bit but it isn't magical potion.

It works good when you use it regularly as a precaution.

(My opinion)

 

[Chaff]

The Panda Nut,
I will try that as soon as the weather improves, thank you very much for the suggestion I will let you know how I get on.

Abrathmultijet,
Couldn't agree more, I only run premium Diesel (done a test with my Passat on premium and my friends on regular same run over 3 months Portsmouth to Edinburgh and back each weekend, his ash loading was much higher) but the Van was ex SSE so I should imagine it spent a long time at idle with the cheapest fuel!

​

 

[Chaff]

Little update, I have vaselened all the joints and checked the fuel filter. All seemed ok. Whilst I had the fuel filter apart i filled it with liquid Molly diesel purge (dint fancy the running from a jar method) started ruff with a lumpy idle, after 5-10 minutes engine sounded better and seemed to behave, the exhaust absolutely stunk though. I have been running it for a couple of days now and touch wood no erratic idle.

Thank you all for your help and suggestions Very much appreciated.