Technical 2007 Ducato X250 2.3 Multijet 'chugging'

[HopwoodBoy70]

Hi all. I really hope someone can help me identify this weird propblem I have please. Apologies for length of post!

Fiat Ducato X250 2.3 Multijet 2007 (motorhome). Last summer I got the dreaded P0638 error. Removed the throttle body and found the actuator was totally corroded so replaced the throttle, including the new adaper cable.

Since then I've been having occasional 'chugging' from the engine when at less than 1500rpm. Doesn't seem to be any pattern to it. Engine can be cold, or it can be hot, can be running for a few seconds or after a long journey and it will do it.

Reading many forums and groups, and looking at suggestions, in order to try to resolve this I have so far also replaced: Mass Airflow Sensor; Boost Pressure Sensor (MAP sensor); EGR Pressure Converter Valve under windscreen scuttle (plus checked no split pipes). Also, about two years ago I had the EGR valve replaced as it was badly blocked.

Yesterday I bought MultiECUScan and performed an ECU relearn in case any of the replaced items needed re-calibrating (throttle body doesn't need it apparently but MAF likely does). I also captured some live ECU data. It shows that upon starting from cold, the engine ran fine for about 13 seconds, and then the chugging started. No DTC codes showing.

OBD2 output showed that Air Intake Quantity, Boost Pressure, EGR Valve, and Throttle Valve all started going crazy, opening/closing etc for no apparent reason and with no input from me. Then after 105 seconds it all stopped and the engine started to run smoothly and without chugging.

When it is chugging, I've noticed that the flexible air supply pipe attached to the throttle body (the one I squeeze in the video) appears to be 'breathing' in and out in that it seems to have air going one way and then the other, almost like back pressure.

I've added a couple of photos - one showing the figures I captured with MultiECUScan, and also a chart showing the four parameters that went crazy, then simply stopped. I've also added a video with the chugging noise (you can hear the change in noise in the video at 15 seconds). Other than that, it seems to run fine, although that's always above 1500rpm.

Any suggestions or recommendations would be very much appreciated. Thanks

 

[theoneandonly]

Can you add the CSV file so i can look at the data.
it automaticaly gets saved in a CSV directory as shown in the setup F9 procedure.
The MAF sensor does need learning to the ECU.
Once ive got the data ill have a reread of the explaination and see what the data says
Here are a number of guides on Multiecuscan

Guides by theoneandonly

www.fiatforum.com

Once ive played with the data i will knock up a specific template for you to try.
in meantime try this one engine hot (start from cold will take 10 mins to warm up)

 

[HopwoodBoy70]

Can you add the CSV file so i can look at the data.
it automaticaly gets saved in a CSV directory as shown in the setup F9 procedure.
The MAF sensor does need learning to the ECU.
Once ive got the data ill have a reread of the explaination and see what the data says
Here are a number of guides on Multiecuscan

Guides by theoneandonly

www.fiatforum.com

Once ive played with the data i will knock up a specific template for you to try.
in meantime try this one engine hot (start from cold will take 10 mins to warm up)View attachment 465517

@theoneandonly Thanks, I'll run this template tomorrow and then send both CSV files. Appreciate your response

 

[theoneandonly]

@theoneandonly Thanks, I'll run this template tomorrow and then send both CSV files. Appreciate your response

No problemo, waiting for the numbers.

 

[deejays]

Hi all. I really hope someone can help me identify this weird propblem I have please. Apologies for length of post!

Fiat Ducato X250 2.3 Multijet 2007 (motorhome). Last summer I got the dreaded P0638 error. Removed the throttle body and found the actuator was totally corroded so replaced the throttle, including the new adaper cable.

Since then I've been having occasional 'chugging' from the engine when at less than 1500rpm. Doesn't seem to be any pattern to it. Engine can be cold, or it can be hot, can be running for a few seconds or after a long journey and it will do it.

Reading many forums and groups, and looking at suggestions, in order to try to resolve this I have so far also replaced: Mass Airflow Sensor; Boost Pressure Sensor (MAP sensor); EGR Pressure Converter Valve under windscreen scuttle (plus checked no split pipes). Also, about two years ago I had the EGR valve replaced as it was badly blocked.

Yesterday I bought MultiECUScan and performed an ECU relearn in case any of the replaced items needed re-calibrating (throttle body doesn't need it apparently but MAF likely does). I also captured some live ECU data. It shows that upon starting from cold, the engine ran fine for about 13 seconds, and then the chugging started. No DTC codes showing.

OBD2 output showed that Air Intake Quantity, Boost Pressure, EGR Valve, and Throttle Valve all started going crazy, opening/closing etc for no apparent reason and with no input from me. Then after 105 seconds it all stopped and the engine started to run smoothly and without chugging.

When it is chugging, I've noticed that the flexible air supply pipe attached to the throttle body (the one I squeeze in the video) appears to be 'breathing' in and out in that it seems to have air going one way and then the other, almost like back pressure.

I've added a couple of photos - one showing the figures I captured with MultiECUScan, and also a chart showing the four parameters that went crazy, then simply stopped. I've also added a video with the chugging noise (you can hear the change in noise in the video at 15 seconds). Other than that, it seems to run fine, although that's always above 1500rpm.

Any suggestions or recommendations would be very much appreciated. Thanks

I always like to start with what may seem obvious and try and keep it simple. The symptoms indicate an intermittent issue and began with replacement of the throttle body and included adapter cable. The symptoms are also indicative of a feedback circuit getting out of phase or being over or underdamped causing oscillation in the circuit. It could also (more likely) be caused by an intermittent connection in the throttle body cabling and connectors or an actual intermittent issue internally with the replacement throttle body. This may be what triggers the chain of events.

 

[HopwoodBoy70]

No problemo, waiting for the numbers.

@theoneandonly

Hi,

As requested, attached are the two CSV files. The one named '250423-1937 - Graph output #4 start from cold - post ECU reset.csv' is the data from my capture yesterday (as above chart), and the one named '250426 - 2007 Ducato X250 - Parameters requested by theoneandonly.csv' is the one with the parameters you requested.

Not all the parameters you asked for in the template were available. I have captured everything that was available. I'm not sure how to export a list of all the options as it appears there is a limit of about 20 that can be captured to a CSV file.

I started the capture you requested with a cold engine and left it capturing for about 20 minutes. However, at about 60 seconds, the engine started running badly again and 'chugging' - you can see the spikes when you graph the data. This continued until about 560 seconds when everything settled down and the engine started to run smoothly again. I didn't touch anything during this time so not sure what triggered it and what resolved it.

I really appreciate you having a look at this for me, and if you have any thoughts on the underlying cause I'd be very grateful. I have checked for air leaks in the vacuum pipes and all other pipes around the EGR but there is nothing obvious.

Thanks for your help