Td5 overboost issue

[discopete]

Hi all,
I have two remaps for the Defender, a stage 1 and 2. Boost has been increased to 1.2 bar with usual rod adjustment. All works well with stage 1 tune according to nanocom. Stage 2, however, will see 1.4 bar and overboost. I've checked wastegate and it appears to be operating freely. The actuator also seems fine and I have purchased a second and tested that against operation of first and concluded they are both working in a similar fashion. I've also check pipework for leaks and nothing detected. Performance is fine except for overboost. I'm going to purchase a VGT/VNT in the new year so not bothered to pull turbo for further inspection. I'm more interested in understanding possible causes.

Peter

[simonmelb]

Hi Peter,

Lots of good very technical background reading that may help here:. Eg this

Overboost Fuel Cut Map | DiscoTD5.com (https://www.discotd5.com/td5-tuning/overboost-fuel-cut-map)

Cheers
Simon

[discopete]

Hi Peter,

Lots of good very technical background reading that may help here:. Eg this

Overboost Fuel Cut Map | DiscoTD5.com (https://www.discotd5.com/td5-tuning/overboost-fuel-cut-map)

Cheers
Simon

Very technical indeed! Looks like a good source of information. Thanks, Simon.

[discorevy]

There could also be the simple reason in your case that the "stage 2" tune is driving the turbine side of the turbo harder, causing the overboost .

Assuming these tunes are both "old school type", and in a Defender which doesn't have a boost modulator.

option 1: Lengthen the rod by 2 turns when "stage 2" is in or

option 2: fit a good quality manual boost controller

option 2 will allow easier adjustment and you will also be able to use it for the VGT.

"New school" or torque based tuning done well is the go when you do fit the VGT.

Shack on here has the VGT tune pretty sussed

[discopete]

There could also be the simple reason in your case that the "stage 2" tune is driving the turbine side of the turbo harder, causing the overboost .

Assuming these tunes are both "old school type", and in a Defender which doesn't have a boost modulator.

option 1: Lengthen the rod by 2 turns when "stage 2" is in or

option 2: fit a good quality manual boost controller

option 2 will allow easier adjustment and you will also be able to use it for the VGT.

"New school" or torque based tuning done well is the go when you do fit the VGT.

I've got 2 ecu's, the stage one on msb and stage 2 modern remap on a nnn. I've also lengthened the rod to various stages in the hope of avoiding overboost without success. My thought is perhaps wastegate not opening fully and hence why I said I won't bother removing turbo to check. My assumption here is if wastegate opens fully it should not overboost. Perhaps that's not the case.

Peter

[discorevy]

Are you able to clarify whether the NNN unit is :

1, Using the Torque based tuning method ?, this is the most modern method of tuning and superior as it allows the tuner to rescale sensor parameters.

2, Running dedicated EU2 files for your engine?, the NNN unit, while more modern and flashable needs to run the correct files for the earlier system.

Does your Nanocom list overboost or out of range Maf reading faults?.
The later EU3 tables use Maf info

[discopete]

Are you able to clarify whether the NNN unit is :

1, Using the Torque based tuning method ?, this is the most modern method of tuning and superior as it allows the tuner to rescale sensor parameters.

2, Running dedicated EU2 files for your engine?, the NNN unit, while more modern and flashable needs to run the correct files for the earlier system.

Does your Nanocom list overboost or out of range Maf reading faults?.
The later EU3 tables use Maf info

Hi Discorevy,
how would I go about clarifying 1 and 2? Can the nanacom be used? The remap is from Storm if that helps with clarification. I will check tomorrow as to whether nanocom lists those faults.

Thanks for your help,
Peter

[discorevy]

Hi Peter

I'm not sure which method that tuner uses but probably safe to say most bigger name tuning companies would have adopted some ( or all ) of Paul's ( offtrack, the link simonmelb provided ) methods in the last 5 years.

If you asked them to specifically do the tune for your vehicle and variant etc then your problem may just be high reading maf sensor. ( if new method, then it should have been rescaled so may be the actual sensor fault )

If you bought the ECU pre tuned ( maybe for something else, later model for eg )then it won't work correctly with yours.

Can you post a log?

[discopete]

Hi Peter

I'm not sure which method that tuner uses but probably safe to say most bigger name tuning companies would have adopted some ( or all ) of Paul's ( offtrack, the link simonmelb provided ) methods in the last 5 years.

If you asked them to specifically do the tune for your vehicle and variant etc then your problem may just be high reading maf sensor. ( if new method, then it should have been rescaled so may be the actual sensor fault )

If you bought the ECU pre tuned ( maybe for something else, later model for eg )then it won't work correctly with yours.

Can you post a log?

Will post a log tomorrow.
The tune was purchased by me and specific for vehicle so hopefully all good there. I was given impression that it was a mechanical issue such as wastegate or a boost leak but thought it strange it is only with this tune. A sensor issue makes more sense.

Peter

[discopete]

Found an old log but not showing when overboosting.

182714

[discopete]

I came across this from sierraferry posted on here back in 2015, which sounds very similar to what I have experienced and looking at the old log the air flow reading was reaching these limits. Hopefully new batch of data will provide answers.

"I'll tell you only what i know for sure:

1. that high air flow fault code is often thrown by the stage 2 remap as the suction is too hard under hard throttle and the air flow reading goes above 650kg/h when the ECM cuts fueling similar like on overboost, you need a live data session with tester to see if it's so before you spend on new sensor but if you want to replace the sensor anyway there is one which can handle better this problem: BMW Mass Air Flow Meter Sensor 5WK9605 5WK9608 5WK96050Z 13621432356 | eBay , (tested it on my own car and friend's auto and it makes a difference), it's perfect fit but it has a wider reading curve though it might not override the cut-off at much higher air flows, the perfect cure for this issue would be an addapted remap to handle the greater air flow reading but if you dont want that you need a voltage clamp on the MAF input to ECM, similar like the boost box to not let the reading exceed 650 even if it's higher... not the best way exactly like boost boxes but it's working(i dont recommend this way even though it works)"

[shack]

A couple of things to note....

Without comparing both ECU tunes with accompanying logs, it's almost impossible to ascertain exactly what is going on, although a faultcode can be pretty conclusive.

If the car originally came with an MSB ECU then it is an EU2 engine, this means that it will definitely not be a MAF related error... But only IF the NNN tune is also EU2.

If it's not then the "overboost" is probably the least of your worries.

Let's just say the correct tune has been provided by the tuner for that engine version, if it has then the only reasons for any kind of boost cut related issue will be to do with either:

1. Boost levels going beyond whatever the tuner has set.

2. Boost levels going beyond what your specific sensor can actually do.

3. Sensor incorrectly calibrated.

If it's MAF related, you've got the wrong tune installed.

If you post a log from a nanocom Evo, leave it in .csv format.

[discorevy]

Yep, new data required, the sensors don't usually take too long when they start to fail.

That previous info relates to old type tuning, as I mentioned before, the MAF should be rescaled with new tuning to accept higher air flow though I only saw a max figure of 624 on the old log ( which, if you were running the MSB ECU at the time wouldn't have given you the symptoms as the MSB doesn't use the MAF in fuelling calcs)
However, the highest actual reading on the old type tuning on a NNN ECU was 675 before cut.

As an aside, I did note being on the verge of over boosting at the 74 second mark.

Of course once again, this all depends on

1: If the Tune file you have purchased is the modern tuning method
2: If yes then they should have rescaled the parameters ( usually around 800max for MAF and 1.6bar if using the stock MAP sensor ).

Probably all very confusing, in short, if you get new data and you observe the airflow on the Nanocom going from high 600's to zero while using the NNN ECU on full noise, that means A: that is the cause of your issue and B: The Tuner didn't rescale the MAF ( new method ) Ditto above 1.42 bar boost.

Tomorrow:thumbsup:

[discorevy]

Writing ( with interruptions of course ) while you posted James

[discopete]

Yep, new data required, the sensors don't usually take too long when they start to fail.

That previous info relates to old type tuning, as I mentioned before, the MAF should be rescaled with new tuning to accept higher air flow though I only saw a max figure of 624 on the old log ( which, if you were running the MSB ECU at the time wouldn't have given you the symptoms as the MSB doesn't use the MAF in fuelling calcs)
However, the highest actual reading on the old type tuning on a NNN ECU was 675 before cut.

As an aside, I did note being on the verge of over boosting at the 74 second mark.

Of course once again, this all depends on

1: If the Tune file you have purchased is the modern tuning method
2: If yes then they should have rescaled the parameters ( usually around 800max for MAF and 1.6bar if using the stock MAP sensor ).

Probably all very confusing, in short, if you get new data and you observe the airflow on the Nanocom going from high 600's to zero while using the NNN ECU on full noise, that means A: that is the cause of your issue and B: The Tuner didn't rescale the MAF ( new method ) Ditto above 1.42 bar boost.

Tomorrow:thumbsup:

Confusing, yes. But get the gist of it. Fault code is 20,2 Overboosting.

182782
182781

[discorevy]

Confusing, yes. But get the gist of it. Fault code is 20,2 Overboosting.

182782
182781

I'm going to say MAP sensor related.
If there was no overboost faults when you first installed the tune, then try changing the sensor.
However, if it has faulted since installing, the tuner may not have calibrated the sensor correctly, or it's out of range as James has mentioned.

Send the log to Storm and ask them if they can fix it.

Edit, If you need to buy a new MAP sensor, especially if going to VGT, get this one and have it calibrated, they are a direct fit 4 bar sensor ( Shack can do it if storm can't )
Bosch 0281002316 Pressure / Temperature Sensor | Automotive Superstore (https://automotivesuperstore.com.au/bosch-0281002316?utm_term=BOSCH-0281002316&srsltid=AeTuncp51QaPc142LXhHNZLKx6gkcK_qhpiXGls46c 2VwZvIyso_tI6tVgs)

[discopete]

I'm going to say MAP sensor related.
If there was no overboost faults when you first installed the tune, then try changing the sensor.
However, if it has faulted since installing, the tuner may not have calibrated the sensor correctly, or it's out of range as James has mentioned.

Send the log to Storm and ask them if they can fix it.

Definitely faulted with new tune. I'll see what Storm have to say and provide any updates/resolutions.
Much appreciate the help you guys have provided.

Peter

[discopete]

Edit, If you need to buy a new MAP sensor, especially if going to VGT, get this one and have it calibrated, they are a direct fit 4 bar sensor ( Shack can do it if storm can't )
Bosch 0281002316 Pressure / Temperature Sensor | Automotive Superstore (https://automotivesuperstore.com.au/bosch-0281002316?utm_term=BOSCH-0281002316&srsltid=AeTuncp51QaPc142LXhHNZLKx6gkcK_qhpiXGls46c 2VwZvIyso_tI6tVgs)

Will do. Thanks again.

Peter