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      10-05-2011, 07:14 PM   #1
JMonakar
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Cobb Accessport - Power Dropoff

Just recently installed the Accesport on my 135i and noticed a few interesting items I wanted to share with the group here. If anyone from Cobb can chime in, it would be helpful.

Noticing a loss of power and different intake sound in the > 4000rpms area after the car has been driven for 45+ minutes on the highway. Think it is related to the Cobb tune cutting timing with higher IAT's. It's 74 ambient out, but I'm seeing charge air temps at 102 at cruise and in the 120 area at WOT.

Car is 100% stock aside from the tune.

Just to rule it out - checked the air filter since I'm noticing this at high load, high rpms. Looks fine, but not a likely culprit as power output feels dramatically stronger in the same conditions during the first half of a long drive.

Are other Cobb owners noticing this?
How about JB3 or Vishnu tune owners?
Thanks,
J
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      10-05-2011, 07:29 PM   #2
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By the way - Sport Tune with 93 octane fuel.

Had a separate set of issues with the Aggressive Tune, and posted separately about them.
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      10-05-2011, 08:07 PM   #3
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Have you tried contacting Cobb and/or datalogging when this happens?
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      10-05-2011, 08:33 PM   #4
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Yes, contacted Cobb.
Have datalogged individual items (ie. charge air temp) - is there a way to datalog everything?
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      10-05-2011, 09:39 PM   #5
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Quote:
Originally Posted by JMonakar View Post
Yes, contacted Cobb.
Have datalogged individual items (ie. charge air temp) - is there a way to datalog everything?
I would wait for their advice as they are the experts and the best we can do is conjecture.

And yes you can log everything... can't quite think of exactly how right now, but there is a way to select a number of parameters to log.
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      10-05-2011, 09:54 PM   #6
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Though 120 is high at WOT, Cobb should behave like the stock tune in which it targets load insead of PSI. Which in warmer temps it should increase boost to meet load to attain the same power output. I'm not an expert though and having an upgraded FMIC I only get to 80F-85F WOT with 65F ambient.
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      10-05-2011, 10:13 PM   #7
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IATs at 120 are completely normal when the car has been run for some time and at WOT (assuming stock IC). I suspect there may be something wrong with your car that's unrelated to the tune, but enhanced by it. Again, like I stated before, it's all conjecture... wait for Cobb's response, post your logs, and we'll take it from there.
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      10-07-2011, 12:58 PM   #8
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Some logs would be a great start to seeing if anything odd is happening. Those IATs are pretty normal and shouldn't cause any kind of issues. When you begin a log (pressing OK while viewing a live monitor), all of the other default log monitors in the log list will automatically be recorded until you hit stop (by pressing OK again). Email us a log of before you have issues and after you have the power drop off and we can take a look for any odd variances.

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      10-09-2011, 08:23 PM   #9
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Will do - thanks guys!
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      10-19-2011, 01:56 PM   #10
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Ian,
Uploading the datalog here, as well. Ambient temps were only 85 degrees.

On the datalog, I have some areas where individual cylinder's are seeing a timing correction and other ares where the overall timing is negative under boost.
I've highlighted some of these areas.

During WOT under these conditions, I'm hearing a pronounced induction noise... not a pinging or knocking sound, but something I'd describe as a roar. Any thoughts?

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Originally Posted by COBB Tuning View Post
Some logs would be a great start to seeing if anything odd is happening. Those IATs are pretty normal and shouldn't cause any kind of issues. When you begin a log (pressing OK while viewing a live monitor), all of the other default log monitors in the log list will automatically be recorded until you hit stop (by pressing OK again). Email us a log of before you have issues and after you have the power drop off and we can take a look for any odd variances.

Ian
ian@cobbtuning.com
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File Type: pdf 10-17-11 Hot Day WOT (odd induction noise).pdf (1.19 MB, 61 views)
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