NefMoto

Starting to run out of options. Mk6 Golf R, MED9.1. Hybrid turbocharger that loves boost, doesn't like flow as much. 1K8907115F. / 510589.

From 4k -> 7k my boost profile tapers from 3000mbar to 2800mbar. Extended runs in 6th gear (around ~150mph) will cause the ECU to throw an overboost code and go into limp. Key cycle fixes it.

All the boost limiters are 2550mbar so they can't be raised. I'm driving duty cycle manually to achieve the required boost.

Short of rescaling the MAP sensor, is there anyway to disable the overboost protection? I've got a full A2L for the software and hunted high and low for the error class and can't see anything obvious.

You mean every single pressure variable and calculation in the system?

No.

Hence why I said "short of". As in I absolutely don't want to do it, but I don't know of any other way - yet.

Have you adjusted ELDOB?

Yep, it's at 1270hPa - max :(

Found something. CLALDR and FFTLDR. Will disabling these prevent limp? Obviously I'd rather not if there's a threshold somewhere else that will be happy with more boost.

You're going to be chasing your tail forever.

Properly scale your pressure variables or GTFO.

Stop looking for shortcuts, they're only going to make things worse.

Scale my pressure variables? This is the problem - the car is hitting an "overboost" condition because of the boost pressure. My only solutions are a) run lower boost b) rescale MAP so it reads lower or c) remove the fault class.

If there is another way, I'm posting to find out what that is. I can't make that more obvious. I don't want to do the shortcut ways, I just don't know what I'm missing to do it "correctly". If you don't know, that's fine - not everybody knows everything. But coming in and selectively reading what I've wrote isn't useful in the slightest. I've made it perfectly clear I don't want to kill fault codes or bodge pressure readings.

When you say controlling duty manually, do you mean using a manual/electronic boost controller? Could you possibly adjust your request to match what you're seeing during those long runs? Does it seem like a time, or deviation thing? Do you have any logs when this happens? Ran into this type of thing a lot with a few BT 2.7T's that weren't using a 5120 a while back on mbc's.

Id imagine he's controlling it via KFLDRL and a fixed duty cycle.

The only way its going to know its over boosting is by load variations, so are you sure the load limiters like LDRXn are high enough?

As above, driving via the ECUs PID. It's definitely a time. I've plotted boost in 4th, 5th and 6th and they're pretty much identical profiles. 6th gear seems to trigger it as it's held out for longer.

5120 changes plus a boost pressure sensor that can read the boost levels you are running, or run under 2500 mbar. Those are your only two choices.

http://nefariousmotorsports.com/forum/index.php?topic=3027.0title=

Yep. The problem is the requested boost, no matter how high, is always 2550mbar absolute. Without ASM changes, I don't know of any way to request more pressure.

5120 changes on MED9?

Yes.

Good luck.

Is that a "go figure it out and be the first to do it" or "it's been done, go find the info and try it"? I've yet to see anyone post other than resident IDA guru Basano but there's been nothing finished that I can see.

So on this, the MAP sensor can read above the max you can set LDRXN too, correct?

Basano ended up using a hack to get the request up. I will not elaborate on what hack, but we exchanged some e-mails with him on said topic.

The only correct way to do this is to rescale some pressure variables... It's not AS much aggro as ME7, it is also nothing LIKE ME7.
You have the FR, you consider yourself a pretty smart cookie, so get to it. I did when the time came - most of the work was done by 3 or 4 of us.

That said, most "pro" tuning companies run 3 bar MAP sensors and underscaled MAF's.
Not much to it. Underscale MAP, underscale altitude sensor to match, underscale MAF so ps_w is not retarded and adjust the throttle tables.
Adjust the pressure scaling in the MVB's to read the correct boost on VCDS if you are so inclined.

If its only happening in 6th gear and it is time dependant then increasing TLDOBAN and or TVLDOBSO should help the over boost. Wont help the 2550mb problem though. You'd have to go fixed n75 duty or scale

Have you checked your short term fuel trim when this happens?

Gman86,

I don't much about IDA, but I do know Allen Bradley PLCs, and Ladder logic diagrams. Let me know if there is anything I can do to help.

what boost does trigger error?
I've build a CDL DSG 4x4 in a ED30 golf and run openloop boost.
1.8 bar midrange and 1.6 highend and never had a limpmode.
3.9 sec 0/100km/h 450 hp.
Do you run open loop over KFLDRAPP?

and check if  boost makes it up to UDSVDMX, than you need to raise that one or put a 4 bar MAP sensor in there.

1.6bar is fine as well. There seems to be a deviation where it is happy. I've ran 1.7 and again was fine. If I could spend time on a dyno, I might be able to run similar power with boost slightly under the deviation threshold and make it up with ignition and cam timing

Yeah this hybrid will quite happily peg the MAP sensor right out the park. I run 70% duty cycle in the midrange where the turbo is keen and it still makes 2bar.

I'll try more boost next week and see if i get same problem.
Should be not too big problem to fix deviation error i think.
I'm on 95% DC and need stronger wastegate on EFR6758, but do like it that it can never peak too high with weak wastegate actuator.