Fuel cut

[Rob Armstrong]

Ok after I installed my new turbo I have been running 11lbs cuz my crappy AF guage is reading lean now. but my car feels slower as if its not making as much power @ 11lbs as it was at 16lbs on the t25. (but I am now useing all of my fuel?)
Now my question is should I try 16lbs or just wait till I get the fuel mods?
or get/borrow a logger and see whats really going on?
And why does it feel as though  I am slower?
if I just turn it up and get fuel cut is that bad and avoid it at all costs?

[Andrew Steele]

If ur car is running like ass after a part replacement/upgrade, log and find out what's goin on.  OR ... just keep turning the boost up and blow something up - then you'll know for sure that something's wrong.

[Michael Cummings]

I second what was said above.  You need to throw it on a datalogger of some kind and take it for a pull to see whats going on.  What kind of turbo did you get, and where did you get it from.  Who did the install, is everything connected properly?
Fuel cut is a precautionary method taken by the car so that nothing bad happens.  It is to be avoided.  
I also had alot of problems when I upgraded my turbo setup and hadn't done supporting mods.  I had alot of problems.  I had to soon upgrade my pump, injectors, air intake system, and picked up an safc to make sure that my air/fuel mixtures were all proper, you may find yourself in this same boat as a turbo upgrade before supporting mods is not the proper route to take.  
Also an a/f guage is not the best thing to trust when it comes to your mixture, it just gives you a rough idea of whats going on.

Definitly don't turn up the boost untill you know what is wrong.

[John Hartman]

blinky light cycling a/f gauges that read from the stock narrow band sensor are not to be trusted for tuning purposes.  Narrow band sensors are only accurate at or very near 14.7:1 air/fuel ratio.

if you want accurate a/f you need a wideband.

You need to log it, like was said above.

You also need to do a boost leak test.  A real test, not just looking at the hose clamps.

and yes, what turbo did you get?

[Miles Frederick]

I believe it's a big 16g, Rob correct me if I'm wrong.

At 11psi you shouldn't be running out of fuel by any means.

 Indicating lean and running like crap could be indicative of an exhaust leak, o2 sensor detects extra oxygen and ecu keeps adding fuel to compensate.  Something I recently dealt with.  A log would indicate lean o2's as your a/f guage is.

Another possibility is a boost leak which would cause more air to be read at the maf, again leading to dumping in way more fuel than necessary.  A log would indicate this by way high maf count.

See if you can get ahold of a logger, but in the meantime it might be worth double checking that stuff.

What are you running for exhaust ?

[Rob Armstrong]

EVO III big 16g bought at Kinetic new installed correctly by myself no boost leaks and if it was a leak would I not be running rich?
I wanted to upgrade my fuel 1st but due to my old turbo crapping out I really had no choice. I bought the 16g cuz I didn't want to run lean as of yet.
and it runs good, just seems slower could be faster... but feels slower

[Miles Frederick]

Well a leak on the exhaust side would indicate lean as the o2 sensor is reading more o2 due to the leak.  But the car would be running rich and slow.

Another thing, when I first bought my 16g (to replace a dead 14b) I had no supporting mods, stock exhaust, etc.  Lag was much more than I was used to and that was on a small 16g.  Although it pulled well in the upper rpm's, throttle reponse was horrible at normal engine speeds.  Opening up the exhaust helped alot.  Larger intercooler piping and 2.5" tb elbow helped as well.

[Chris Andrews]

Taking everything at face value, you've put in a slightly bigger turbo, you have no leaks or other problems, and the narrowband telling you that you're possibly running slightly leaner. Your (quite frankly) innaccurate butt-dyno tells you that you *might* be slower.

Do you have an SAFC or similar?  Although a wideband would be best, you could use the SAFC to richen up slightly and see if the car feels faster (butt-dyno again).   It can work.

But if you seek tuning perfection, its a waste of time.

As John said, wideband tune it.  And as Miles said, maybe its time for a bigger exhaust if you're still on the stock system.  A bigger turbo is only as good as the supporting mods.

To answer your fuel cut question,  lots of us have hit it at some point or another and the engine didn't go boom.  But unlike sex, its not something to keep doing, once you discover it.  :twisted:

[Rob Armstrong]

yes, yes I know that I need bigger exaust and fuel control aswell as other stuff that I PLAN ON GETTING. $$$ is a issue at the present time and fuel is coming before exaust. I want the sickest sounding stock exaust around :twisted: