Computer Diagnostics and Tuning Technical discussion on diagnostics and programming of the F-body computers

Datamaster Logged run, RPM's not very smooth?

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Old Jun 2, 2008 | 08:21 PM
  #1  
z28_theantirice's Avatar
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Datamaster Logged run, RPM's not very smooth?

Got around to doing a logged run, after I got my fuel system worked out. Car runs great. But after reviewing the log, the RPM's do not look very smooth in the graphs. I am by no means an expert with Datamaster so maybe this is completely normal?

File located below
http://www.mediafire.com/?gjjoxnnmjw7
Old Jun 3, 2008 | 05:28 PM
  #2  
Injuneer's Avatar
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Your RPM at idle is set to 900rpm, but its varying from 675-975rpm in the section I looked at. While that's a fairly wide range, it appears you have a decent sized cam, with about 66-69kPA MAP at idle (hence the DTC for high MAP, low vacuum). Low vacuum seems to be fairly common with the LE cams. How well it will idle will be highly dependent on the quality of the tune. Near the end of the log, the MAP goes really high at idle (80kPa) and the IAC is open to over 90 counts to hold the idle.

Once you start to drive, the RPM seems to respond correctly to changes in the throttle position.
Old Jun 3, 2008 | 06:39 PM
  #3  
z28_theantirice's Avatar
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Originally Posted by Injuneer
Your RPM at idle is set to 900rpm, but its varying from 675-975rpm in the section I looked at. While that's a fairly wide range, it appears you have a decent sized cam, with about 66-69kPA MAP at idle (hence the DTC for high MAP, low vacuum). Low vacuum seems to be fairly common with the LE cams. How well it will idle will be highly dependent on the quality of the tune. Near the end of the log, the MAP goes really high at idle (80kPa) and the IAC is open to over 90 counts to hold the idle.

Once you start to drive, the RPM seems to respond correctly to changes in the throttle position.
Injuneer, thank you for taking the time to look at my log. Based on what you can see would you say everything is running pretty good? On a cold start with the car in gear brakes on not moving I usually get a Check Engine light for the High Map, which quickly goes off once I let off the brakes.
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