550s, no low end power

[symple]

Hey everyone,

I installed some 550's this weekend along witha 2g exhaust mani (what a PITA that was).

Anyways, I have my AFC set about -15 across the board for both hi and low throttle. The car does fine when it reaches just over 3000 RPM. However, up until then it's sluggish as hell. Does this mean I need to lean it out quite a bit more?

After reading some posts in the initial settings thread, I'm getting some mixed opinions.



My 02 voltage is flaky now also. It doesn't oscillate at idle anymore. Most of the time it stays at 0.03 - 0.07. However, as soon as i hit the gas, it bounces back to normal, topping out at .94.

I have 0 knock at all RPM up to 7000. I just wanted an opinion or 2 before I start leaning it out/turning up the boost.


my mods include:

MAS w/ lower honeycomb removed and screw backed out flush.
K&N + dejon intake pipe
14b
650's
Rewired Walbro 190
SAFC II
3" Downpipe and 3" the rest of the way back
2g Exhaust mani
mbc set at 15psi
logger


Thanks, and sorry for the messy post.

--Symple

 

[DSMtuned]

Here is a really helpful discussion on SAFC tuning.

http://racingknowledge.org/topic.asp?TOPIC_ID=1011

Good luck!!

-Craig

 

[CanadianTSi]

I think you should try leaning it out somemore below 3000, it's probably really rich before the boost hits...

 

[DSMtuned]

Originally posted by CanadianTSi
I think you should try leaning it out somemore below 3000, it's probably really rich before the boost hits...

I think the opposite is true. He said that his O2s are staying about zero until he really gets on the gas. They should be cycling. I would rev the car up to each of your Ne points rpms and and hold it at each one. Tune the SAFC until the O2s cycle.

Then you can watch O2 trim and tune it for about zero also. This will get you close for the low throttle settings. Over time you can watch your fuel trims and adjust accordingly to keep them around 100%. I aim for 110% for the best fuel mileage at those low settings.

Read that write-up on Racing Knowledge. It super helped me gain an understanding when I first learned.

Good luck,

-Craig

 

[symple]

Thanks for the help guys. I'll try that and get back to you with the results!


--Symple

 

[symple]

Well, the o2's cycle at idle now... [+10% @ 800 RPM];[+ 6% @ 1000];
[-6 @ 1400]; [-7 @ 2600, 3000, 3200, 4200, 4600, 5000, 5600, 6000, 6800]

Those are the low settings.

High are: [+0 @ 800] ; [ -2 @ 1200] ; [ -6 @ 1400] ; [ -12 @ 2600, 3000, 3200, 4200, 4600, 5000, 5600, 6000, 6800]

My fuel trims are:

118.7% FTRL -low
102.5% FTRM - mid
118.7% FTRH -high

I've tried edging those toward 100, but haven't had any luck so far. It seems that no matter what I do, the low and high are always at 118.7%.

Thanks again for the help!

--Symple

 

[DSMtuned]

The Low Fuel Trims should update very quickly (or at least they do on my car). The Mid and Highs update much slower. You can the settings a bit and then wait a few days to see what happens.

For the trims to update you have to be running in a certain Karmen range for a couple minutes straight. This is hard to do if you aren't driving on the highway or trying to do this.

IIRC, the ranges for the fuel trims are around:

Low 0-125 karmen
Mid 125-175 karmen
High 175-300 karmen

They're something like that. The fuel trims aren't that big of a deal unless they are railed to one limit or the other. You really need to be concerned with WOT tuning.

 

[kpt4321]

Low fuel trim is approximately 1000rpm, mid is approximately 2k rpm, and hi is approximately 3k-4k rpm. Richen the 1k point up a tad bit, and bump the 3k point up a tad bit.

The trims take a long time to update, that is normal.

Tune the car using the guide on this site in the tech articles section, before you worry about how it runs. You can't try to diagnose tuning problems on an untuned car.