Datalogging Results. Anyone know exactly what this means.

[EPLegacyGT]

Hey NSFW.

 

I know have the logs which might help. First is a cold idle and yes i made it long for nothing just wanted to make sure i catch the stutter, 2nd is a 2nd and 3rd gear pull (useless) and the last is idle when the car was at operating temperature. Let me know.

 

I think its worth saying that all spark plugs have been changed recently by dealer and i recently checked the airbox and after MAF hose for cracks of anykind and nothing was found ( MAF also cleaned )

Data Log Cold Idle, Tuesday, July 20th 2010.csv

Data Log Hot Idle, Tuesday, July 20th 2010.csv

Data Log 2nd and 3rd gear, Tuesday, July 20th 2010.csv

[NSFW]

At what time in the first log did the stutter happen? I actually can't tell from the log itself, so I don't know how helpful I can be.

 

However the long term fuel trim is maxed out, which suggests a boost leak or a badly done MAF scaling, or maybe just an aftermarket intake that needs to be tuned for. If you have the stock intake, then I'm guessing a leak. The short term + long term trims are able to compensate, but just barely.

[EPLegacyGT]

Ok, so to start ill have to make another log to pin point exactly when the stutter is happening as for the possible problems.

 

1. Ill need to check for a boost leak (suggestions: maybe the t fitting)

2. I didn't change anything with the MAF scaling?

3. Still retain OEM intake. ( might change to Cobb SF to solve problem)

 

Do you have any suggestions on how to check for either of these problems. Ill search the forum aswell

[NSFW]

Check every hose under the hood, make sure both ends are attached to something, and check the length of it for cracks/splits.

 

I'm not confident that this can be diagnosed via data logs - I was hoping to see something abnormal in the log that would help, but I don't. RPM isn't even changing significantly anywhere in the long idle log you posted. The problem seems to be too subtle to show up.

[EPLegacyGT]

Would you rull out injection or spark problems?

 

I also noticed the the throttle position in both the cold and hot idle changes % from 3.14 to 3.53?

 

and the ignition advance is fluctuating between 8 to 14?

[NSFW]

Ignition advance flutters on my car as well, and it has a smooth idle. Even on a perfectly healthy car, idle RPM fluctuates a bit, and it's my understanding that the ECU uses ignition timing to try to correct for the speed changes.

 

I would not rule out injector or spark problems, those are probably the next things to check after you've ruled out a vacuum leak. But the LTFT suggests a vacuum leak, and fixing that would only take time, not money (maybe a trivial amount of money if you need a clamp or something) so that's the place to start.

[keithk831]

Just by looking at the idle RPMs, it looks like there's a vacuum leak. Check the seals around the intercooler, as well as the "t" fitting underneath it. Those are the most common areas.

[EPLegacyGT]

K will do this weekend. Ive checked that T fitting before and all was well. Do you recommend a method to check other leaks such as intake and vaccum line. I was thinking of using a can of ether to check for leaks on the intake side to see if the idle raises? Thanks

[EPLegacyGT]

I got 2 new datalogs one is idle other shows a shit load of knock can someone analize this further. the one named datalog is the long one showing knock. Other is idle.

TUNER_100913211906.csv

datalog4.csv

[bugblatterbeast]

you are likely knocking on tip-in because there is insufficient fueling. either roll on to the throttle gently or increase your tip in values. a 5% increase should be a good starting point.

 

as for the idle roughness, I'd tend to agree with NSFW. you probably have a leak somewhere. try unplugging the maf so the car runs in SD mode (when the car is off). if it idles fine like that, you very likely have a leak. if you are going to search for the leak by spraying stuff, you might want to avoid using ether. water is a lot safer.

[EPLegacyGT]

K thanks.

[EPLegacyGT]

Moderator, please close thread.