help me diagnose the problem - limp mode

[petarkunew]

Hi everyone ,
I have this problem and there is a lot of guessing from everyone, even Honda dealer so would like to pick the brain from experts from this forum.

My car is honda Accord 09 , 2.2 diesel
285k on the clock.
DPF removed by previous owner 10 years ago , no problem with anything big on the car so far.

Let me try to describe the problem as much i can.
From time to time car is entering sort of limp mode , very slow or almost no acceleration in 5/6 gear and slow acceleration over 2k revs in lower gears.
It usually happens when driving on motorway in 6th gear , but this happened last day from cold start when i was going to local shop.
After car goes to limp mode , no arrows for changing gears etc are shown.
After power off/power on everything is back and i could go few days without the problem.
There are no codes on simple obd2 diagnostic on my side neither in Honda dealership where i was yesterday.
I told them in dealership that dpf is removed and they are saying that can cause some of the codes not to appear if it is ECU is not remapped correctly.
I would tell also that they might not hit the issue as i am not sure how long they have a chance to drive it so it will enter to limp mode.

I replaced week a go fuel filter but no changes to the issue.
They told me they are suspecting some HP pressure regulator but they are only guessing.

Can anyone help narrow down the fault or suggest me what to try in order to narrow it down.
I really like the car , have it for 9 years already , not a fault on it. Would be pity to change if I dont have to.

Thanks in advance and best regards,
Peter

 

[F6HAD]

Hi Peter, the fact your gearshift indicators stop working (and I suspect also your cruise control) point to either a software checksum problem or indeed a mechanical problem where the software has been butchered to incorrectly mask an error.

I can help if you drop me a line, it will involve reflashing the ecu with a new repair file.

 

[petarkunew]

F6Had is one real gentleman, he took time to explain me what needs to be done etc. It is not simple solution but ECU seems to be hiding the problem and without proper code it is all guessing game. Unfortunately I am in Ireland and that is complicating whole thing.
Now i need to think what to do next.
Thanks

 

[Richard B]

You can do a remote flash procedure. You need a reliable laptop guaranteed not to lose power during the procedure, and an OBD2 connector and software to read the current map and stored values, and write an adjusted map to the ECU. You can do a mild tune and EGR delete at the same time.

 

[Channel Hopper]

Hi Peter, the fact your gearshift indicators stop working (and I suspect also your cruise control) point to either a software checksum problem or indeed a mechanical problem where the software has been butchered to incorrectly mask an error.

I can help if you drop me a line, it will involve reflashing the ecu with a new repair file.

Could it possibly be one or two circuits failing intermittently, whilst I have no experience of the Mk8 have there been instances of damp/corrosion in / around the fusebox/relay areas ?

 

[F6HAD]

If it is then I’ve personally never seen it, but I have seen multiple examples of the gearshift indicators not working due to bad software.

 

[Channel Hopper]

If it is then I’ve personally never seen it, but I have seen multiple examples of the gearshift indicators not working due to bad software.

I didn't read correctly the loss of indicators was/is a classic symptom of flawed mapping, apologies