Can you say "Boost Leak"?

Grinder34

Track Monkey
Welp, i did some logging and i'm pretty sure i have a boost leak. I dont hear anything but the a/f corrections are ALL over the place. I guess the "fueling specific" logs are the most important ones in this case? Anyways, here are the logs:
https://docs.google.com/folder/d/0Bycs16LC4qhLUzhCTlhQSkoySlU/edit

Does that look like a boost leak to you, or something else?

If so, do you think I'm putting my car at risk? I dont know if i'll be able to fix it within the next few days (ordering a boost leak tester at the moment)--so i want to know if there's anything i can/should do in the mean time?
 
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HolyCrapItsFast

Drinks beer!
They look fine to me... I don't see anything to suggest a leak. They could stand to use a minor tweeaking but there is nothing wrong that would casue any kind of concern. I don't see any significant knock either. I only looked at the ones that were labeled Fueling because they had the fuel trims.
 

Grinder34

Track Monkey
What about the crazy A/F Corrections?

Fueling1 has a min correction of -25 and a max of 21.09, for example.
 

HolyCrapItsFast

Drinks beer!
Maybe reset the ECU and take another log. This way we are not looking at learned data. When you reset it you need to give it a few minutes of idle time before you start logging.
 

HolyCrapItsFast

Drinks beer!
What about the crazy A/F Corrections?

Fueling1 has a min correction of -25 and a max of 21.09, for example.

This just looks like tip in to me. It happens when you change throttle position. You need to focus on the steady portions of the log. My eye just naturally filters out the erroneous data.
 

HolyCrapItsFast

Drinks beer!
Also when you log like this you want smooth throttle inputs to minimize the effects of tip-in and over-run
 

Vermont

New member
Everything holy has said is dead on. I haven't looked at the logs yet but that is mostly due to me being lazy.... :D

Ok looked at the logs now. You are going to need to reset the ecu and then drive around like holy said. With no sharp throttle inputs. Also next time if you could not change the sorting of them based on correction, just leave it based on time so we can see when and where what is happening. It is fully normal to see AF corrections jump around when you let off the throttle or stab it real quick. That is just the ecu trying to catch up with what you are physically asking of it.

Another indication of what to look at is the leaned corrections. Your learned AF corrections are still within 5 of 0. Corrections are going to widely swing around but if your learned has moved to 5 or -5 and is still dropping you need to look into a retune. If it goes down to -25 or +25 then you have a physical problem that the ecu is unable to correct for (I.E. blown coupler, bad gasket, and ect.).

Just a quick lesson on what AF correction is and what AF learning is. Air-Fuel Correction is what the ECU is seeing that it needs at that second to meet target AFR's. Either pulling fuel, Negative numbers or adding fuel, Positive numbers. When the ecu sees AF Corrections in a certain area long enough it starts to add those corrections to learned memory which is Air-Fuel Learned. There are four different categories of learned that the ecu uses, ranges A-D. A is idle and very very light throttle, with them going up from there. If you are watching your cars corrections and learned right after you reset the ecu you can actually see the corrections starting high and then slowly dropping down towards zero. While at the same time the Learned will slowly move away from zero as the ecu learns what it needs to do to meet target afr. The rule of thumb is that anything over 5 or -5 shows you need to retune (usually just scale the maf).

In your log from what I saw is that the learned as about 4. So you are within the target area. It is just what you would expect from an ots map. Not perfect but close enough for the ecu to sort out the rest.
 

Grinder34

Track Monkey
Also next time if you could not change the sorting of them based on correction, just leave it based on time so we can see when and where what is happening.

You can sort them real-time in google docs ;) At least you should be able to, I think i gave everyone write privileges.
 
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