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Title: car feels like its in limp first drive but next drive is boosting normally Post by: airtite on June 14, 2012, 01:37:39 AM Hi guys
my wifes car has been down while I have been doing the brakes so she has been driving the a4 1.8t its been running my tune for quite a while now, the tune is fairly aggressive... anyway I jumped into the car the other day too take it for a panel beater quote after the wifes recent shopping trip where someone clipped the left side in the parking bay, now for the weird part started the car drove out the drive and the car felt a bit flat first thing that came to mind was boost leak so drove to the panel shop stopped got the car assessed on the drive home the car was back up and running and boosting fine! took it for another drive this morning (2nd quote) but first checked for faults, no faults so decided too log it and hey same issue just not boosting stopped at the panel shop, and on the drive home same thing back up and running and boosting fine, logs attached if anyone has any ideas? As I side note I know the requested boost is fairly high its like that so I could adjust the requested too suite the max the turbo can give and since I have been driving the v8 I havent really spent more time on the tune ;) Title: Re: car feels like its in limp first drive but next drive is boosting normally Post by: nyet on June 14, 2012, 02:49:26 PM You are requesting too much boost too soon.
http://s4wiki.com/wiki/Tuning#Positive_deviation Why are you requesting 22psi at 2000rpm? Can your turbos make 22psi at 2000rpm? Title: Re: car feels like its in limp first drive but next drive is boosting normally Post by: airtite on June 14, 2012, 11:09:04 PM You are requesting too much boost too soon. http://s4wiki.com/wiki/Tuning#Positive_deviation Why are you requesting 22psi at 2000rpm? Can your turbos make 22psi at 2000rpm? Yup I know the turbo cant do 22psi at 2000rpm the idea was too max it out so I can see what the turbo CAN deliver and then adjust accordingly, regarding the positive deviation its not logging that as a fault and if you look at the logs the throttleplate position is at 100% when going WOT anyway so its not a softlimp condition. Title: Re: car feels like its in limp first drive but next drive is boosting normally Post by: nyet on June 14, 2012, 11:54:58 PM Your requested boost says otherwise.
Positive deviation won't always throw a code or close throttle, it will sometimes simply reduce requested boost. Title: Re: car feels like its in limp first drive but next drive is boosting normally Post by: airtite on June 15, 2012, 12:21:24 AM ok when I am looking at the feels_like_limp log, the requested was always lower than actual the other log which felt like the car normally is yes agreed requested was higher BUT that run the car was 100% fine it was the other run where the issue was and it was like that since first start on the day, whats weird now is that after I have been driving the car again for the last 2 days its been fine, its almost like it needed to be driven a little harder than my wife was driving it.
Title: Re: car feels like its in limp first drive but next drive is boosting normally Post by: janne on June 15, 2012, 12:21:57 AM some 1.8t ecus including bug.
It is in limp mode when you start it and next start all is ok. Put leakdetection start value about 2000rpm. In bug sw it try to diagnose boost leak in 200 rpm. Regards Title: Re: car feels like its in limp first drive but next drive is boosting normally Post by: airtite on June 15, 2012, 12:25:02 AM some 1.8t ecus including bug. It is in limp mode when you start it and next start all is ok. Put leakdetection start value about 2000rpm. In bug sw it try to diagnose boost leak in 200 rpm. Regards thanks will try that, I still need to code out my sai, n279 etc as well Title: Re: car feels like its in limp first drive but next drive is boosting normally Post by: AndiS4 on June 15, 2012, 12:30:43 AM Shouldnt it be possible to keep everything as it is and change kfdluls in your case? KFVPDKLD Could also be an option.
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