Boost leak, or just too much fuel? Logs inside.

[Twinky-Ninja]

I've finally worked out some major demons out of my Talon this weekend, so I took it out to log some pulls. Fuel mods: Re-wired Wally 255, stock injectors, -6an fuel feed, FPR base press @ 37psi (1:1).
Boost set at 13.5psi on the 14b w/ mbc. Stock internals/intake tract. Fuel management is still stock.

I noticed on every pull at WOT boost builds to 13psi, AFR slides to 10.5'ish, then as RPMS build, boost starts falling off to around 11. AFR also drops to extremely rich levels, sub 10..

I'm pondering whether this is a result of a boost leak, or is it just a boost spike with too much fuel. I don't have control over fuel yet (other than pressure), now could it be the extra fuel pressure causing it to richen up like this? (2nd, 3rd, and 4th gear WOT pulls)

Here is a pic of the log, and the link for the file. I'm using LogWorks2. Sorry about the poor quality of the pic.. Blue is afr, green is boost, and black is rpm..

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http://www.davebaxterjr.com/Talon/13JanTest1mod.log

Any input is appreciated.

Dave

 

[GSXanimal]

Checking for a boost leak is never a bad idea. Best of luck

 

[spyderturbo007]

Keep in mind that the highest airflow map in the ECU shoots for an AFR of 9.5:1. Not that you shouldn't check for leaks, but if you're running on that airflow map, the ECU is going to get as close to 9.5:1 as possible.

 

[2gGSX]

Possible causes include boost leaks, pre-turbine exhaust leaks, bad/loose wastegate, cracks in the turbine housing and/or wastegate area, a damaged turbo, and base timing being off.

-Boost leak test for the boost leak.
-Feel for exhaust leaks by hand (off a cold start of course).
-Try swapping out the wastegate actuator and/or pushing on it by hand and seeing if it moves that way.
-Check for cracks by removing the turbo and visually inspecting it.
-Check for shaftplay and excessive oil in the LICP. Large clouds of black smoke during/after boosting the turbo is also a red flag.
-Check base timing with a timing light.

 

[Rob10_99]

Right on the money,
Get the idle RPM to stablize 750+- and get the timing right first, then go for boost leaks.

Idle surging?
Get the Coolant warm before you do anything first,