Sluggish 4th Gear

[lanky_mps]

Ive been having my car mapped by Skiptowncat recently and he has done a GREAT job with it and I have 100% confidence in his mapping abilitys. Lately ive noticed tho that 4th gear feels quite sluggish and flat in power compared to all the other gears. Say I got WOT all the way through 3rd gear and change to 4th gear, 3rd gear feels pretty savage and has loads of power but as soon as I put my foot down in 4th gear it just feels like there is barely any power there at the start and then picks up a bit but no way near as much as in the other gears. Change into 5th gear and it feels as savage as 3rd gear does.

Ive messaged Skiptowncat with the logs ive attached to this post so that he can hopefully find out why it is and whats causing it but thought id see what input others may have on the situation.

Attached you will find 4 4th gear WOT logs that I have just done.

[skiptownmcat]

It's strange because I have the highest loads set for 4th gear. As I said, I'll take a look later.

[skiptownmcat]

There is a lot of random high KR in the logs which wasnt there before and every time its at a different rpm/load point. Wgdc is also pegged at 100% and for some reason the maf cal has drifted off, I think you may have a boost leak and are in need of some itv22 spark plugs.

[skiptownmcat]

Just noticed the way the load climbs as well, it should rocket straight up. I'm saying defo boost leak.

[tranceporter]

it seems that you are hitting quite a good amount of boost of 20+ psi with quite high ignition timing. That also could be another cause of KR, especially if the weather was hotter outside, resulting in higher BAT's.

[mituc]

Too much timing past 5200-5300rpm for the fire spitting K04. At 100% WGDC past 5000rpm you're definitely pushing 17PSI of fire into your engine. Drop the APP from the logs, it's not important at all, and add the BAT to see where those are.

There is no obvious sign of a boost leak, boost leaks to not lead to high KR. Also, the commanded and actual AFR at WOT are a bit off, sometimes they differ even with 0.4 which is not dramatic but not ideal as well, so you need to work on the OL maf cal a bit more because the leaner AFR's may cause this KR as well especially when pushing the K04 way beyond its efficiency limits like you do now.
100% WGDC past 5krpm (or anything above like 80%) will result in turbo shaft play in no time, considering that you're not just doing one WOT pull at every 2 hours but driving consistently fast.

So here is what you need to consider:
1. lower the load targets past 5500rpm around or under 1.55-1.6 As a dumb rule, you can lower the load targets by 0.05 in those areas where you're at 100% WGDC and stop when you are around 80-85.
2. pull 1 or 1.5 degrees of advance in those areas where you have 3 degrees of retard and half a degree where you have less than 1.5.
3. review your OL MAF cal!!

Making more power is not always about high boost (they are in direct relation, but not when pushing a turbo to its efficiency limits or beyond that). You can make more power by pushing less and cooler air into the engine and using more advance. But high boost + high advance + high BAT's = hate.
Instead of aiming for 17PSI at red line you could aim for only 16 and have the BAT's cooler with at least 15C. That + a touch richer AFR's may allow you to keep the advance timing values about where they are now and give you more power.

[skiptownmcat]

Good points, but wgdc wasn't at 100% in the last lot of logs and that load doesn't climb in a straight line or hit target till 3700rpm which would indicate a boost leak. I didn't touch the higher up loads or timing in the last revision so it's strange that all of a sudden these issues have appeared out of nowhere. We've just gone back to stock timing until he can do a leak check and get some itv22's which will help.

[mituc]

I see. However, I think a boost leak would also affect the AFR's, we should see richer AFR's than the commanded (I mean significantly richer), while in this case the AFR's are actually a bit leaner and it's jsut a result of no previous learning on the current MAF cal.
WGDC at 100% may also indicate that the turbo is about to let go. As far as I understand the OP still had the stock DP on, so hitting load 2 or more (I think on K04 with upgraded HPFP internals you can go up to 2.2 safe on pump gas in the 3500-5000 range). Also, if the previous logs were taken in cold weather the story may be a bit different because the very high load targets can be hit a bit easier.

I have some experience with the K04 and high flow DP but 0 experience with K04 + HPFP internals, so I know how high one can aim with the K04 on stock internals but not sure how high on upgraded internals, therefore what I said above are just my opinions on what I think it may/could happen or be the problem in this particular case.

[tranceporter]

honestly i feel that the KR in those logs actually caused the desired afr to differ from actual afr, because the ecu started to dump in more fuel to recover from KR. So I would not touch the maf cal, until we have a run which is KR free as much as possible, and then try and correct the differences in actual and desired afr. Setting the ignition timing back to stock is a great idea. I agree with mituc as in, lower boost and higher timing is a better way to achieving MBT or desired torque, instead of higher boost and higher timing. Then again I should not be the one talking coz I am targeting 2.5 load at 25 psi in this weather..lolol.

[skiptownmcat]

His peak loads in 4th are (iirc I'm not near my computer) [email protected] then 1.985 till 4.5k then it drops sharply and tapers off to 1.3@redline.