Technical Twin EGR issues - 'EGR Cooler Syndrome' Symptoms but different Fault Codes - HELP!

[theoneandonly]

As Jackwhoo has said - it not only shuts off completely as part of the engine shutdown (to reduce shudder etc), but plays a very important part in the HPEGR valve throughput (directing gas flow from the HPEGR valve) and thus the complete gas flow of the motor. @theoneandonly there are so many actuators and feedback loops - which is the reason why I urge you to take on a more holistic approach to analysis, as to compare just a couple of parameters in isolation can prove difficult, particularly when an engine has borderline issues. (It is very easy to spot a completely blocked cooler - but more difficult if it is only partially blocking.

Once it has passed a certain degree of blocking the diagnosis is now simple and rectivation a known route, However, why do people still have difficulties getting a Fiat Pro Dealer to resolve this Problem? Is there an advantage to jumping to an early partial blocking diagnosis, when other issues may be present or even if not. Is there some methodology that could be used for those that periodicaly clean the LPEGR cooler to identify how much time or distance to a P0401? This could be useful for a number of people.

 

[Dancingbear]

As Jackwhoo has said - it not only shuts off completely as part of the engine shutdown (to reduce shudder etc), but plays a very important part in the HPEGR valve throughput (directing gas flow from the HPEGR valve) and thus the complete gas flow of the motor. @theoneandonly there are so many actuators and feedback loops - which is the reason why I urge you to take on a more holistic approach to analysis, as to compare just a couple of parameters in isolation can prove difficult, particularly when an engine has borderline issues. (It is very easy to spot a completely blocked cooler - but more difficult if it is only partially blocking.

@deejays do you have any suggestion on how i should move forward or what would that holistic approach look like?

I'm a non mechanic with a sick vehicle and without a bottomless pit of cash. I believe what @theoneandonly has done for me goes well above and beyond in terms of 'helping a stranger' and has at least given me some direction.... as i see it at the moment (based on his assistance) I have proved that all tested parameters are 'acceptable' aside of the turbo which needs some further investigation, that i probably need a new DPF and that it would be prudent to get the LPEGR cooler examined during that process.

There is an 'engine tuning' garage near me who offer a free 30 minute diagnostic but i find it hard to believe more thorough, holistic or detailed than the help I have received so far, and my local main Fiat dealer appears to have no appetite of discussing diagnostics, but is more than happy to quote for an eye watering replacement without even considering the root cause.

Any further suggestions to move forward in a cost effective and pragmatic manner would be greatly appreciated!

 

[theoneandonly]

@Dancingbear What progress have you made with the throttle body? That seemed to be an outstanding issue.

 

[Dancingbear]

I purchased a new unit on friday eve which is still to be delivered - hopefully it will go on easily 'and start the van with no snags. I'm of the understanding that it can 'relearn' itself for starting the engine but may require more for cruise control and that MES should be able to do this... i haven't looked yet - does this sound correct?

Also i'm unsure whether the throttle body issue is a frustrating coincidence, a contributing factor or possibly a root cause of the issues - thoughts???

Again, thanks!!

 

[theoneandonly]

Again i will say this is unusual for a twin egr but typical of older ducatos with leaky skuttles that sometimes have egr issues as well as throttle body. @LandyAndy . have a search.

 

[deejays]

@deejays do you have any suggestion on how i should move forward or what would that holistic approach look like?

I'm a non mechanic with a sick vehicle and without a bottomless pit of cash. I believe what @theoneandonly has done for me goes well above and beyond in terms of 'helping a stranger' and has at least given me some direction.... as i see it at the moment (based on his assistance) I have proved that all tested parameters are 'acceptable' aside of the turbo which needs some further investigation, that i probably need a new DPF and that it would be prudent to get the LPEGR cooler examined during that process.

There is an 'engine tuning' garage near me who offer a free 30 minute diagnostic but i find it hard to believe more thorough, holistic or detailed than the help I have received so far, and my local main Fiat dealer appears to have no appetite of discussing diagnostics, but is more than happy to quote for an eye watering replacement without even considering the root cause.

Any further suggestions to move forward in a cost effective and pragmatic manner would be greatly appreciated!

Considering you have ordered a new throttle body it would seem logical for you to fit it and see if that fixes the issue. If after fitting it there are still problems, then further investigation would be required. There are many on this forum who are willing to help and some have considerable expert knowledge built over a lifetime. You only have to look at some of the interactions on this forum. Apart from interactions in the public space on this forum, a considerable amount of help and advice occurs in the non-public space (Private Conversations). The holistic approach I am referring to is to NOT view individual parameters in isolation. For example, the actual fresh air flow can at times be greater or less than the desired, and if this is viewed in isolation without reference to any other parameters it could be deemed as a fault. But the actual airflow is not only influenced by ECU lookup tables but also physical restraints inherent in the engine depending on the current operating conditions. My approach to diagnosis using MES is to analyse the parameters within MES (not exporting to excel or similar - I don't see the need) and understanding there are numerous feedback loops and actuators and sensors that are linked by those feedback loops. A holistic approach to that analysis is required - particularly in borderline issues where a direct conclusion cannot be made easily. Even the best FIAT PRO mechanics have problems trying to analyse and diagnose some of the issues - it is not an easy task. Please post the outcome from fitting the new throttle body, and we can take it from there if more help is required.

In the diesel engine, the gas pedal is not linked to the throttle body, but to the injector flow control. The throttle performs a different function as has already been described. Totally different to a petrol engine.

 

[Dancingbear]

Considering you have ordered a new throttle body it would seem logical for you to fit it and see if that fixes the issue. If after fitting it there are still problems, then further investigation would be required. There are many on this forum who are willing to help and some have considerable expert knowledge built over a lifetime. You only have to look at some of the interactions on this forum. Apart from interactions in the public space on this forum, a considerable amount of help and advice occurs in the non-public space (Private Conversations). The holistic approach I am referring to is to NOT view individual parameters in isolation. For example, the actual fresh air flow can at times be greater or less than the desired, and if this is viewed in isolation without reference to any other parameters it could be deemed as a fault. But the actual airflow is not only influenced by ECU lookup tables but also physical restraints inherent in the engine depending on the current operating conditions. My approach to diagnosis using MES is to analyse the parameters within MES (not exporting to excel or similar - I don't see the need) and understanding there are numerous feedback loops and actuators and sensors that are linked by those feedback loops. A holistic approach to that analysis is required - particularly in borderline issues where a direct conclusion cannot be made easily. Even the best FIAT PRO mechanics have problems trying to analyse and diagnose some of the issues - it is not an easy task. Please post the outcome from fitting the new throttle body, and we can take it from there if more help is required.

In the diesel engine, the gas pedal is not linked to the throttle body, but to the injector flow control. The throttle performs a different function as has already been described. Totally different to a petrol engine.

Thanks for the comprehensive reply, that does make sense and the more l learn the more I realise I don't know!!

I guess my biggest anxiety with just driving as normal once the throttle body is fitted to identify more 'problems' is that all evidence suggests the DPF is compromised, and surely this will eventually lead to another egr failure or other expensive replacement!??

I will take it for a good run hopefully to trigger an auto regen and monitor soot% etc with MES - anything else you'd suggest monitoring specifically?

Throttle body has arrived, Lug bent, sent back, awaiting a new one... it probably would have been ok if I'd have drilled / filed it down, but for the wait of a few days, I'll wait...

Watch this space and thanks again!!!