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Author Topic: MED9 Overboost problem  (Read 15887 times)
lacaci
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« on: October 23, 2012, 09:42:55 AM »

Hello, I'm fairly new to bosh ecu's. I have a 2008 VW Golf that has a GT30 turbo with an external wastegate. The stock wastegate actuator is connected for sake of dtc as well as the blow-off actuator.

Car has bigger injectors and a high pressure fuel pump mod with a slightly bigger size airflowmeter tube. So far I have the cruising and driveability dead on and long term fuel trims are at 0~0.2 via KRKATE without touching the lambda maps.

Whenever I try to go about 20psi boost it will throw a code p0234 turbocharger overboost. Sometimes it throws an underboost code too. I have tried following the wiki and not requesting too much boost too soon on all of the boost tables and following the boost ramp of the turbo setting the high limits above 4000rpm as far as 200%. Is there a way to eliminate these errors? Under 18psi the car runs perfect, afrs are in the safe side, and timing tables are untouched. As soon as I turn the boost (manual) controller up it closes the throttle body and throws a code (sometimes pending)
« Last Edit: October 23, 2012, 09:44:49 AM by lacaci » Logged
RaraK
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« Reply #1 on: October 23, 2012, 03:01:59 PM »

yes there are many maps and individual values associated with overboost/underboost codes.  Are you using maestro?
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Rick
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« Reply #2 on: October 23, 2012, 03:46:23 PM »

And i think i know exactly which map is missed Cheesy
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RaraK
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« Reply #3 on: October 23, 2012, 07:32:55 PM »

 Tongue
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lacaci
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« Reply #4 on: October 23, 2012, 09:17:49 PM »

yes there are many maps and individual values associated with overboost/underboost codes.  Are you using maestro?

I'm using WinOLS translating a damos for the tsfi that's floating around here.
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lacaci
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« Reply #5 on: October 23, 2012, 09:19:45 PM »

And i think i know exactly which map is missed Cheesy

And your point is?
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lacaci
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« Reply #6 on: October 23, 2012, 09:23:08 PM »

I see the way this is going...please understand I'm not looking for someone to give me a map or a tune. I don't mind reading documents if they point me in the right direction. No need for useless responses like rick's
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Rick
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« Reply #7 on: October 24, 2012, 02:47:32 AM »

If you use a manual boost controller, then you will be forever fighting the ECU.  Get rid of that and use the N75 and tune your boost from there.

Rick
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majorahole
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« Reply #8 on: October 29, 2012, 04:03:16 PM »

could he just make the delta larger between requested and actual?
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Rick
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« Reply #9 on: October 30, 2012, 02:02:20 AM »

He could,

but it would make far more sense that requested and actual are fairly close so everything is working as it should.
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tomasvs
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« Reply #10 on: November 06, 2012, 07:18:21 PM »

Hello, I'm fairly new to bosh ecu's. I have a 2008 VW Golf that has a GT30 turbo with an external wastegate. The stock wastegate actuator is connected for sake of dtc as well as the blow-off actuator.

Car has bigger injectors and a high pressure fuel pump mod with a slightly bigger size airflowmeter tube. So far I have the cruising and driveability dead on and long term fuel trims are at 0~0.2 via KRKATE without touching the lambda maps.

Whenever I try to go about 20psi boost it will throw a code p0234 turbocharger overboost. Sometimes it throws an underboost code too. I have tried following the wiki and not requesting too much boost too soon on all of the boost tables and following the boost ramp of the turbo setting the high limits above 4000rpm as far as 200%. Is there a way to eliminate these errors? Under 18psi the car runs perfect, afrs are in the safe side, and timing tables are untouched. As soon as I turn the boost (manual) controller up it closes the throttle body and throws a code (sometimes pending)


If you deal't allready with the load and boost limit maps  then raise the maf limit map. On the damos floating around here is at 1C4696 just before the KFKHFM. On the damos is not defined.(settings are address 1C4696 9x8 2d inverse and factor 0.1 if i am not mistaken..
« Last Edit: November 06, 2012, 07:40:36 PM by tomasvs » Logged
lacaci
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« Reply #11 on: November 13, 2012, 11:11:33 AM »

If you use a manual boost controller, then you will be forever fighting the ECU.  Get rid of that and use the N75 and tune your boost from there.

Rick

Thank you. I have tried using the stock valve. With the stock values it was overshooting the boost target by alot. Remember I no longer have an internal wastegate. But will give it another shot.
« Last Edit: November 13, 2012, 11:15:02 AM by lacaci » Logged
prj
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« Reply #12 on: November 13, 2012, 11:15:30 AM »

Thank you. I have tried using the stock valve. The problem is fairly similar since the external wastegate on a big turbo opens way different than the stock wastegate on the stock turbo. I may request X amount of load at Y rpm but there is no way that the engine can generate enough pressure to give me that load, then with the stock duty cycles I might overshoot or never hit the target.

Yes of course, this will happen. So tune it so that it operates correctly...
Dial in the correct duty cycles, linearization and so on, and the boost control will work just fine.
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lacaci
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« Reply #13 on: November 13, 2012, 11:40:07 AM »


If you deal't allready with the load and boost limit maps  then raise the maf limit map. On the damos floating around here is at 1C4696 just before the KFKHFM. On the damos is not defined.(settings are address 1C4696 9x8 2d inverse and factor 0.1 if i am not mistaken..

Thank you for your response. That map is defined in the A2L and is KFMLDMX but the address is offset on my file. To help fellow readers, the map's factor is indeed .1 (Kg/hr), 2D inverse, X-axis is RPM factor 40, y-axis is %DK factor 0.024414.

I will try increasing this globally and will post the results.
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airtite
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« Reply #14 on: November 13, 2012, 11:58:55 PM »

any chance you can share or post a link to that damos you are using?
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