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Vac Leak/Boost leak?


gkinslow

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I don't ever seem to reach target boost anymore and am unsure why.

 

The car has felt slower lately but i'm sure some of that is just me getting used to it as my DD since I sold my other car.

 

Would anyone with more experience with datalogging/tuning care to take a look at this and point me in the right direction?

 

Opinions appreciated.

datalog3.1.csv

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No its a protune. And I haven't tried a reflash yet.

 

I am running a vf52, stock tmic, cobb intake, GS ebcs, a Perrin DP, and a Cobb fuel pump.

 

I assumed that if I did have a leak it was a very minor one as I'm still getting close to target boost.

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I'd expect the VF52 to pretty easily hit your targets by/before 3500 rpm even when starting the pull at 3k, esp w/ your 61-62F ambient temps. My 05 OBXT is running the same turbo w/ supporting upgrades and typically hits 19+ psi by/before 3200 rpm, even with 80-90F intake temps.

 

Is the car sitting in traffic or running at low speeds for long before you run your tests? (heat soak scenario)

 

I find it curious that your logged WGDC sits at a fixed 42.75% despite being like 2 psi below boost target below 3600 rpm. Might want to add WGDC Max, Turbodynamics Integral, and Turbodynamics Proportional to your log list to see if your boost is being capped by WGDC.

 

Also you can do a quick log at idle that includes your fuel trims (AF Learning 1A, B, C, D) to see if you have leak symptoms. Alternatively you could just put the key into the ON position and check/note the 4 AF Learning values on the AP display. Shouldn't need to log them on an ongoing basis though.

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To add to my prev reply... you also have FBKC and FLKC events in that log. Single count FBKC bn 3400-4000 rpm which at least decays to zero, and a double count FLKC bn 4400-4800 rpm. The FLKC bn 4400-4800 is probably learning itself out since it likely started as a -2.8 deg correction that has more recently had 0.35 deg added back in and is currently appearing as a -2.45 deg correction. I'd keep an eye out on the 3400-4800 rpm region. If you continue to see knock there, esp double count FLKC, and you don't have any detectable leaks, the tune might need some minor adjustments in that rpm range.
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A datalog that includes WGDC Max and the Turbodynamics parameters would probably show what might be going on. My car is running same turbo with very similar supporting upgrades and pretty easily hits its 19.5 psi targets in ambient temps ranging from 25F to 90+F. If his boost isn't being limited by a leak, minor changes to the WGDC IAT Comp table might be all that's needed. I needed to make a variety of changes to that table to get the boost response consistent across the seasons (I'm in NJ).
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Also you can do a quick log at idle that includes your fuel trims (AF Learning 1A, B, C, D) to see if you have leak symptoms. Alternatively you could just put the key into the ON position and check/note the 4 AF Learning values on the AP display. Shouldn't need to log them on an ongoing basis though.

 

Can you explain this a little more? What "numbers" would indicate a leak symptom when checking these four values at idle?

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Nothing has changed on the car as far as mods and tune since I was consistently hitting the same target boost.

 

Did a pretty heavy 5th gear pull at WOT the other day and reached the target, but unfortunately I wasn't logging at the time.

 

I'm waiting for a new clutch master cylinder to arrive tomorrow and then I'll be doing some more logging to figure out where/when I'm adding/subtracting fuel.

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Nothing has changed on the car as far as mods and tune since I was consistently hitting the same target boost.

 

Did a pretty heavy 5th gear pull at WOT the other day and reached the target, but unfortunately I wasn't logging at the time.

 

I'm waiting for a new clutch master cylinder to arrive tomorrow and then I'll be doing some more logging to figure out where/when I'm adding/subtracting fuel.

 

Your target boost should be in 3rd gear, a 5th gear pull isn't recommended and will be higher than your target boost (since there is no boost by gears).

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I understand that, I was really just commenting that the system (as is) is capable of achieving 18.27 psi. I may have posted this in the wrong section or accidentally omitted pertinent details.

 

I have been running my current tune (protune by Corbin Johnson) for quite some time now successfully. I'm just trying to determine where my problem lies since I'm no longer achieving target boost in 3rd gear.

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If there isn't any appreciable leaks, ambient temps might be affecting things. Post up a 3rd gear log that includes WGDC Max and the TD parameters, which should help rule in/out if your boost is being capped by WGDC. Like I mentioned, I found it curious that your WGDC was sitting at a flat 42.75% while you were still nearly 2 psi below target.
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I will add those parameters to my next log. Which will hopefully be Wed evening since my master cylinder just shipped today and its next day air shipping.

 

You gotta love when a new issue appears while still troubleshooting the original :spin:

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I took this log this morning shortly after the blue light went off and after zero stop and go traffic. Ambient temp around 85 degrees.

 

Most of the parameters I added are over my head but I'm still getting nowhere near target boost under WOT in third gear.

datalog6-26-16.csv

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If you look at WGDC and WGDC Max you'll see they're virtually identical throughout the entire pull. That implies your boost is being capped by WGDC.

 

TD Proportional sits at 6.something and TD Integral doesn't change/increase until after you start getting closer to target boost around 5k rpm where TDP starts to drop off, allowing TDI to start to increase. Maybe the tune is using TDP to block TDI from winding up, but regardless it looks like you're being capped by WGDC. Probably best to send that log over to your tuner to review.

 

The FLKC in the log is not accompanied by a change in Knock Sum, so that pull didn't see any additional real knock, it's showing up in the log as a previously learned/proactively applied timing correction. Probably inquire about the FLKC to your tuner. I don't think you need or should reflash the tune. If you really want to see if the FLKC will learn itself out, just keep driving into that rpm region to see if repeated pulls through that range causes the ecu to start decaying the FLKC. If you really want to clear the FLKC (not recommended since that will very possibly cause real knock to recur and cause the FLKC to be reinstated anyway), you can simply reset the ECU. Note that that will clear the FLKC table as well as your fuel trims.

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Thanks for the input. I will send that log to my tuner in the morning.

 

If the tune hasn't changed and I used to meet target boost during 3rd gear pulls, wouldn't changing the tune just be compensating for another issue?

 

I guess I'm confused how the tune could be causing issues if it hasn't changed in 8 months.

 

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if it's been a while since the last ecu reset or reflash, check your fuel trims. those values, if they've settled out, could indicate whether you do/don't have a leak.

 

our core upgrades list is pretty similar incl the VF52 and GS EBCS. I'm not near my logging laptop atm to check some historical logs but iirc in order for me to hit my 19.5 psi target above 3000 rpm I needed ~42% WGDC post-compensations, perhaps a few % more than that w/ 90F intake temps like you were seeing in your latest log. your log shows WGDC at ~36% in that 3000 rpm range.

 

are you pretty sure you were hitting target boost in these warm temps in the past?

 

Edit: forgot your target is about 1psi less than mine, but if your fuel trims look reasonable it still seems you might just need a little more WGDC to get to your target. I'm sure your tuner can help w/ this or any related issues you might have.

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Thank you for the insight. I'll be contacting my tuner today. I think temps may be playing a part in this after all.

 

My dyno tune was done in Nov and last summer I was having the motor rebuilt.

 

I have a new GS TMIC waiting to replace my stock tmic. Maybe I'll throw that on and see if it helps the situation.

 

Also need to do some better heat management under the hood. Currently only using a GS tutbo heat shield.

 

I've been looking at adding a turbo blanket and DP blanket as well.

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