Technical 2011 2.3 Multijet erratic idle when hot

[bauweto]

Hi, I have a problem with my 2011 FIAT 2.3 multijet. When the motor is hot, the motor becomes erratic when in idle.
I 've been to multiple fiat shops and they all say they can't find the problem because there is no indication in software fault lists.

Found also a lot of posts on this topic but not 1 of them exactly the same. Many of them suggest the EGR valve, though not certain.

The symptoms: when the engine is hot and the motor is in idle it has a tendency to stall but then picks up again. This process is repeated every second or so but after some time, there is an audible intervention by another system which I can only describe as a deep 'brrr' when it activates . After this systems kicks in the engine runs fine in idle.
I have an audio recording of the engine running in idle if anyone's interested.

Anyone have an idea? Or had the same experience? Your help is much appreciated!!

Regards,
Tom

 

[Crossingkeeper]

Just a guess based on the information you have given: the throttle valve is situated on the inlet manifold on the front of the engine just behind the radiator.

This has an motor actuator and is a known issue on this engine (same year as mine so yours will also have the original pre-modified version)

I believe that the valve is not linked to the ECU so any failures will not throw up a fault code.

 

[bauweto]

Hi, thanks for your reply! You already gave much more information than the FIAT dealers I spoke to!

"same year as mine so yours will also have the original pre-modified version": does this mean that later models have a modified motor actuator on the throttle valve?

Is there anyway I can test this without changing the actuator?

 

[Crossingkeeper]

You could compare your valve against this ebay link for the later version (redesigned to prevent water ingress which seized them up)

http://www.ebay.co.uk/itm/Fiat-Duca...201812?hash=item33b3487314:g:2VMAAOSwPc9Wx1zH

Not sure how to check them though I recollect someone posting that they took the hose off to check for free movement of the flap against it's spring loading.

Because of the cost and the hassle involved in replacing it, it would be worth getting a second opinion first, however the valve controls idle speed and is connected to the EGR valve so symptoms fit.

If you search on this forum for 'throttle valve' there are a lot of threads about this (but note that the valve for the 3L engine is different)

NB it's also worth checking the electrical connector first for dirty/corroded contacts

 

[rolopolo]

Just a random shout here,
On my van last year, ok it's a 3.0 not 2.3, but I had the same issue, whilst hot, it wasn't every second but regular, drop in revs at idle, slow recovery, and a distinctive grumble at the same time,
Garages couldn't fix it, guessed the throttle valve, guessed the egr (both of these could be your issue) but I had no faults showing!

Garage ordered throttle valve, thinking a good starting point as they had not long fitted one, thinking it was duff and could be changed under warranty

But

One morning, I was cleaning the headlamps as they were muddy, when from the outside I heard the engine revs drop and took a look under the bonnet,
To find one of the cooling fans rattling away, the motors bearing had collapsed or worn out,

New fans and cowl fitted, job sorted

Worth a check (check with A/C on and off as one fan is the a/c which it was my a/c one that had gone,
Not a cheap part as its a complete cowling and motors

 

[CDK]

"there is an audible intervention by another system which I can only describe as a deep 'brrr' when it activates"

Such a sound is made by the vacuum valve that controls the EGR valve. I also hear it sometimes even shortly after the engine is switched off.
In my van it doesn't affect idle rpm because the EGR valve has been jammed shut and the vacuum line is blocked, but the cable to the vacuum valve is still connected. I guess the valve itself must be the culprit because with the engine switched off, power to the valve is also off.

 

[bauweto]

Hi guys,

Just a quick update on what's happened so far such others can read it that maybe have the same problem.

I went to a Fiat dealer and they've replaced the diesel throttle valve housing together with turbo pressure sensor. The throttle valve was filled with exhaust waste.
It runs fine now at idle, no more drops.

They told me to once in a while hit the gas and run it in high revs for a few minutes such that exhaust waste is blown out of the valve. They also told me that this problem usually occurs with campers (such as mine) as we usually drive more 'relaxed'

Thanks everyone for the input!

Cheers,
Tom