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Author Topic: Overboost logs  (Read 6554 times)
chirp
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« on: February 14, 2011, 05:50:45 PM »

I was wondering if someone could take a look at my logs and tell why I am overboosting? Is my N75 not working properly? Can you tell that from a log?
Overboosting started when I gutted my cats and precats.

Thanks.
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NOTORIOUS VR
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« Reply #1 on: February 14, 2011, 06:13:02 PM »

What tune do you have? Have you pressure tested?
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chirp
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« Reply #2 on: February 14, 2011, 06:44:58 PM »

Actually I am not sure what tune I have. It was on the car when I bought it 2 years ago. Up until now it has been smooth and has had no issues.
A 2 months or so ago I developed a rough idle/ misfire. About 2 weeks ago I started overboosting.

I have pressured cheked. I found 2 small leaks and fixed them, but i made no difference in my overboosting.
I used to spike at 15 and taper to 11. Now I spike at 19, ECU cuts boost to 10, and them it levels out at 12.
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NOTORIOUS VR
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« Reply #3 on: February 15, 2011, 09:30:00 AM »

Well then I would start to look deeper into the N75, check plugs, boots, CP's, etc..

Also, you know this is a tuning forum right?  This isn't really a help me my car is broken forum...
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chirp
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« Reply #4 on: February 15, 2011, 10:49:22 AM »

I understand this is not a fix my car thread. I asked the question on audizine and nef told me to post my logs here because there was alot of knowledge floating around over here. Thats cool if you don't want to help. I didn't know I someone could tell if the N75 was not acting right by looking at the logs.

I am tuning as well, but this boost spike has put a hold on changing anything else.

No problem man.
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Tony@NefMoto
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« Reply #5 on: February 15, 2011, 10:58:10 AM »

Also, you know this is a tuning forum right?  This isn't really a help me my car is broken forum...

I think it is valid to discuss these types of issues here because we all need experience debugging the ME7 before we can tune it better.
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Tony@NefMoto
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« Reply #6 on: February 15, 2011, 11:07:03 AM »

I see one place in the log where the actual boost is 2170 and the requested boost is 1750. Looking at the log before that, it seems as though the ECU overshot the requested boost. This would mean that the boost either took too long to build up, or that it was too slow to drop off once the requested was reached.

It is possible that gutting your cats and precats has reduced your back pressure enough that the boost no longer drops off quickly.

Most GIAC tunes disable the boost deviation limit and so this is never a problem with them. If you read your ECU with the NefMoto flashing tool, we could see what the boost deviation limit has been set to.

I am assuming you have scanned for error codes with VAG-COM?
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chirp
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« Reply #7 on: February 15, 2011, 11:32:33 AM »

Yes I have scanned with vag. One code for positive deviation.
I Did read my ECU last night and saved it. I am going to start looking at it tonight. I'd like to figure out how to delete the upper limit of the boost, or at least raise it so it wouldn't cut back after it spikes.
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nyet
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« Reply #8 on: February 15, 2011, 02:47:24 PM »

btw i have a data plotter for VCDS/ECUx

http://nyet.org/cars/ECUxPlot/
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vwaudiguy
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« Reply #9 on: April 19, 2011, 10:15:30 PM »

I know it's an old thread, but have you looked at your map sensor? It seems unlikely for boost to rise that quickly over less than 1 sec. I have seen this problem a few times before, and it was a false reporting map sensor/wiring problem.
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